OpenSubdiv/examples/glViewer/glViewer.cpp

//
//   Copyright 2013 Pixar
//
//   Licensed under the Apache License, Version 2.0 (the "Apache License")
//   with the following modification; you may not use this file except in
//   compliance with the Apache License and the following modification to it:
//   Section 6. Trademarks. is deleted and replaced with:
//
//   6. Trademarks. This License does not grant permission to use the trade
//      names, trademarks, service marks, or product names of the Licensor
//      and its affiliates, except as required to comply with Section 4(c) of
//      the License and to reproduce the content of the NOTICE file.
//
//   You may obtain a copy of the Apache License at
//
//       http://www.apache.org/licenses/LICENSE-2.0
//
//   Unless required by applicable law or agreed to in writing, software
//   distributed under the Apache License with the above modification is
//   distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
//   KIND, either express or implied. See the Apache License for the specific
//   language governing permissions and limitations under the Apache License.
//

#include "../common/glUtils.h"

#include <GLFW/glfw3.h>
GLFWwindow* g_window=0;
GLFWmonitor* g_primary=0;

#include <far/error.h>

#include <osd/cpuEvaluator.h>
#include <osd/cpuGLVertexBuffer.h>

#ifdef OPENSUBDIV_HAS_OPENMP
    #include <osd/ompEvaluator.h>
#endif

#ifdef OPENSUBDIV_HAS_TBB
    #include <osd/tbbEvaluator.h>
#endif

#ifdef OPENSUBDIV_HAS_OPENCL
    #include <osd/clGLVertexBuffer.h>
    #include <osd/clEvaluator.h>
    #include "../common/clDeviceContext.h"

    CLDeviceContext g_clDeviceContext;
#endif

#ifdef OPENSUBDIV_HAS_CUDA
    #include <osd/cudaGLVertexBuffer.h>
    #include <osd/cudaEvaluator.h>
    #include "../common/cudaDeviceContext.h"

    CudaDeviceContext g_cudaDeviceContext;
#endif

#ifdef OPENSUBDIV_HAS_GLSL_TRANSFORM_FEEDBACK
    #include <osd/glXFBEvaluator.h>
    #include <osd/glVertexBuffer.h>
#endif

#ifdef OPENSUBDIV_HAS_GLSL_COMPUTE
    #include <osd/glComputeEvaluator.h>
    #include <osd/glVertexBuffer.h>
#endif

#include <osd/glMesh.h>
#include <osd/glLegacyGregoryPatchTable.h>
OpenSubdiv::Osd::GLMeshInterface *g_mesh = NULL;
OpenSubdiv::Osd::GLLegacyGregoryPatchTable *g_legacyGregoryPatchTable = NULL;

#include "../../regression/common/far_utils.h"
#include "../common/glHud.h"
#include "../common/glUtils.h"
#include "../common/glControlMeshDisplay.h"
#include "../common/glShaderCache.h"
#include "../common/objAnim.h"
#include "../common/simple_math.h"
#include "../common/stopwatch.h"
#include <osd/glslPatchShaderSource.h>



/* Function to get the correct shader file based on the opengl version.
  The implentation varies depending if glew is available or not. In case
  is available the capabilities are queried during execution and the correct
  source is returned. If glew in not available during compile time the version
  is determined*/
static const char *shaderSource(){
#if ! defined(OSD_USES_GLEW)

static const char *res =
#if defined(GL_ARB_tessellation_shader) || defined(GL_VERSION_4_0)
#include "shader.gen.h"
#else
#include "shader_gl3.gen.h"
#endif
;
#else
        static const char *res = NULL;
        if (!res){
            static const char *gen =
#include "shader.gen.h"
                ;
            static const char *gen3 =
#include "shader_gl3.gen.h"
                ;
            //Determine the shader file to use. Since some opengl implementations
            //define that an extension is available but not an implementation 
            //for it you cannnot trust in the glew header definitions to know that is 
            //available, but you need to query it during runtime.
            if (GLUtils::SupportsAdaptiveTessellation())
                res = gen;
            else
                res = gen3;
        }
#endif
        return res;
}

#include <cfloat>
#include <vector>
#include <iostream>
#include <fstream>
#include <sstream>

enum KernelType { kCPU = 0,
                  kOPENMP = 1,
                  kTBB = 2,
                  kCUDA = 3,
                  kCL = 4,
                  kGLSL = 5,
                  kGLSLCompute = 6 };

enum DisplayStyle { kDisplayStyleWire,
                    kDisplayStyleShaded,
                    kDisplayStyleWireOnShaded };

enum ShadingMode { kShadingMaterial,
                   kShadingVaryingColor,
                   kShadingInterleavedVaryingColor,
                   kShadingFaceVaryingColor,
                   kShadingPatchType,
                   kShadingPatchCoord,
                   kShadingNormal };

enum EndCap      { kEndCapNone = 0,
                   kEndCapBSplineBasis,
                   kEndCapGregoryBasis,
                   kEndCapLegacyGregory };

enum HudCheckBox { kHUD_CB_DISPLAY_CONTROL_MESH_EDGES,
                   kHUD_CB_DISPLAY_CONTROL_MESH_VERTS,
                   kHUD_CB_ANIMATE_VERTICES,
                   kHUD_CB_DISPLAY_PATCH_COLOR,
                   kHUD_CB_VIEW_LOD,
                   kHUD_CB_FRACTIONAL_SPACING,
                   kHUD_CB_PATCH_CULL,
                   kHUD_CB_FREEZE,
                   kHUD_CB_DISPLAY_PATCH_COUNTS,
                   kHUD_CB_ADAPTIVE,
                   kHUD_CB_SINGLE_CREASE_PATCH,
                   kHUD_CB_INF_SHARP_PATCH };

int g_currentShape = 0;

ObjAnim const * g_objAnim = 0;

bool g_axis=true;

int   g_frame = 0,
      g_repeatCount = 0;
float g_animTime = 0;

// GUI variables
int   g_fullscreen = 0,
      g_freeze = 0,
      g_shadingMode = kShadingPatchType,
      g_displayStyle = kDisplayStyleWireOnShaded,
      g_adaptive = 1,
      g_endCap = kEndCapBSplineBasis,
      g_singleCreasePatch = 1,
      g_infSharpPatch = 0,
      g_mbutton[3] = {0, 0, 0},
      g_running = 1;

int   g_screenSpaceTess = 1,
      g_fractionalSpacing = 1,
      g_patchCull = 0,
      g_displayPatchCounts = 1;

float g_rotate[2] = {0, 0},
      g_dolly = 5,
      g_pan[2] = {0, 0},
      g_center[3] = {0, 0, 0},
      g_size = 0;

int   g_prev_x = 0,
      g_prev_y = 0;

int   g_width = 1024,
      g_height = 1024;

GLhud g_hud;
GLControlMeshDisplay g_controlMeshDisplay;

// performance
float g_cpuTime = 0;
float g_gpuTime = 0;
Stopwatch g_fpsTimer;

// geometry
std::vector<float> g_orgPositions;

int g_level = 2;
int g_tessLevel = 1;
int g_tessLevelMin = 1;
int g_kernel = kCPU;
float g_moveScale = 0.0f;

GLuint g_queries[2] = {0, 0};

GLuint g_transformUB = 0,
       g_transformBinding = 0,
       g_tessellationUB = 0,
       g_tessellationBinding = 1,
       g_lightingUB = 0,
       g_lightingBinding = 2;

struct Transform {
    float ModelViewMatrix[16];
    float ProjectionMatrix[16];
    float ModelViewProjectionMatrix[16];
    float ModelViewInverseMatrix[16];
} g_transformData;

GLuint g_vao = 0;

// XXX:
// this struct meant to be used as a stopgap entity until we fully implement
// face-varying stuffs into patch table.
//
struct FVarData
{
    FVarData() :
        textureBuffer(0) {
    }
    ~FVarData() {
        Release();
    }
    void Release() {
        if (textureBuffer)
            glDeleteTextures(1, &textureBuffer);
        textureBuffer = 0;
    }
    void Create(OpenSubdiv::Far::PatchTable const *patchTable,
                int fvarWidth, std::vector<float> const & fvarSrcData) {
        Release();
        OpenSubdiv::Far::ConstIndexArray indices = patchTable->GetFVarValues();

        // expand fvardata to per-patch array
        std::vector<float> data;
        data.reserve(indices.size() * fvarWidth);

        for (int fvert = 0; fvert < (int)indices.size(); ++fvert) {
            int index = indices[fvert] * fvarWidth;
            for (int i = 0; i < fvarWidth; ++i) {
                data.push_back(fvarSrcData[index++]);
            }
        }
        GLuint buffer;
        glGenBuffers(1, &buffer);
        glBindBuffer(GL_ARRAY_BUFFER, buffer);
        glBufferData(GL_ARRAY_BUFFER, data.size()*sizeof(float),
                     &data[0], GL_STATIC_DRAW);

        glGenTextures(1, &textureBuffer);
        glBindTexture(GL_TEXTURE_BUFFER, textureBuffer);
        glTexBuffer(GL_TEXTURE_BUFFER, GL_R32F, buffer);
        glBindTexture(GL_TEXTURE_BUFFER, 0);
        glBindBuffer(GL_ARRAY_BUFFER, 0);

        glDeleteBuffers(1, &buffer);
    }
    GLuint textureBuffer;
} g_fvarData;

//------------------------------------------------------------------------------

#include "init_shapes.h"

//------------------------------------------------------------------------------
static void
updateGeom() {

    std::vector<float> vertex, varying;

    int nverts = 0;
    int stride = (g_shadingMode == kShadingInterleavedVaryingColor ? 7 : 3);

    if (g_objAnim && g_currentShape==0) {

        nverts = g_objAnim->GetShape()->GetNumVertices(),

        vertex.resize(nverts*stride);

        if (g_shadingMode == kShadingVaryingColor) {
            varying.resize(nverts*4);
        }

        g_objAnim->InterpolatePositions(g_animTime, &vertex[0], stride);

        if (g_shadingMode == kShadingVaryingColor ||
            g_shadingMode == kShadingInterleavedVaryingColor) {

            const float *p = &g_objAnim->GetShape()->verts[0];
            for (int i = 0; i < nverts; ++i) {
                if (g_shadingMode == kShadingInterleavedVaryingColor) {
                    int ofs = i * stride;
                    vertex[ofs + 0] = p[1];
                    vertex[ofs + 1] = p[2];
                    vertex[ofs + 2] = p[0];
                    vertex[ofs + 3] = 0.0f;
                    p += 3;
                }
                if (g_shadingMode == kShadingVaryingColor) {
                    varying.push_back(p[2]);
                    varying.push_back(p[1]);
                    varying.push_back(p[0]);
                    varying.push_back(1);
                    p += 3;
                }
            }
        }
    } else {

        nverts = (int)g_orgPositions.size() / 3;

        vertex.reserve(nverts*stride);

        if (g_shadingMode == kShadingVaryingColor) {
            varying.reserve(nverts*4);
        }

        const float *p = &g_orgPositions[0];
        float r = sin(g_frame*0.001f) * g_moveScale;
        for (int i = 0; i < nverts; ++i) {
            float ct = cos(p[2] * r);
            float st = sin(p[2] * r);
            vertex.push_back( p[0]*ct + p[1]*st);
            vertex.push_back(-p[0]*st + p[1]*ct);
            vertex.push_back( p[2]);
            if (g_shadingMode == kShadingInterleavedVaryingColor) {
                vertex.push_back(p[1]);
                vertex.push_back(p[2]);
                vertex.push_back(p[0]);
                vertex.push_back(1.0f);
            } else if (g_shadingMode == kShadingVaryingColor) {
                varying.push_back(p[2]);
                varying.push_back(p[1]);
                varying.push_back(p[0]);
                varying.push_back(1);
            }
            p += 3;
        }
    }

    g_mesh->UpdateVertexBuffer(&vertex[0], 0, nverts);

    if (g_shadingMode == kShadingVaryingColor)
        g_mesh->UpdateVaryingBuffer(&varying[0], 0, nverts);

    Stopwatch s;
    s.Start();

    g_mesh->Refine();

    s.Stop();
    g_cpuTime = float(s.GetElapsed() * 1000.0f);
    s.Start();

    g_mesh->Synchronize();

    s.Stop();
    g_gpuTime = float(s.GetElapsed() * 1000.0f);
}

//------------------------------------------------------------------------------
static const char *
getKernelName(int kernel) {

         if (kernel == kCPU)
        return "CPU";
    else if (kernel == kOPENMP)
        return "OpenMP";
    else if (kernel == kTBB)
        return "TBB";
    else if (kernel == kCUDA)
        return "Cuda";
    else if (kernel == kGLSL)
        return "GLSL TransformFeedback";
    else if (kernel == kGLSLCompute)
        return "GLSL Compute";
    else if (kernel == kCL)
        return "OpenCL";
    return "Unknown";
}

//------------------------------------------------------------------------------
static void
rebuildMesh() {
    using namespace OpenSubdiv;

    ShapeDesc const &shapeDesc = g_defaultShapes[g_currentShape];
    int level = g_level;
    int kernel = g_kernel;
    bool doAnim = g_objAnim && g_currentShape==0;
    Scheme scheme = shapeDesc.scheme;

    Shape const * shape = 0;
    if (doAnim) {
        shape = g_objAnim->GetShape();
    } else {
        shape = Shape::parseObj(shapeDesc.data.c_str(), shapeDesc.scheme,
                                shapeDesc.isLeftHanded);
    }

    // create Far mesh (topology)
    Sdc::SchemeType sdctype = GetSdcType(*shape);
    Sdc::Options sdcoptions = GetSdcOptions(*shape);

    Far::TopologyRefiner * refiner =
        Far::TopologyRefinerFactory<Shape>::Create(*shape,
            Far::TopologyRefinerFactory<Shape>::Options(sdctype, sdcoptions));

    // save coarse topology (used for coarse mesh drawing)
    g_controlMeshDisplay.SetTopology(refiner->GetLevel(0));

    g_orgPositions = shape->verts;

    delete g_mesh;
    g_mesh = NULL;

    // Adaptive refinement currently supported only for catmull-clark scheme
    bool doAdaptive = (g_adaptive!=0 && scheme==kCatmark);
    bool interleaveVarying = g_shadingMode == kShadingInterleavedVaryingColor;
    bool doSingleCreasePatch = (g_singleCreasePatch!=0 && scheme==kCatmark);
    bool doInfSharpPatch = (g_infSharpPatch!=0 && scheme==kCatmark);

    Osd::MeshBitset bits;
    bits.set(Osd::MeshAdaptive, doAdaptive);
    bits.set(Osd::MeshUseSingleCreasePatch, doSingleCreasePatch);
    bits.set(Osd::MeshUseInfSharpPatch, doInfSharpPatch);
    bits.set(Osd::MeshInterleaveVarying, interleaveVarying);
    bits.set(Osd::MeshFVarData, g_shadingMode == kShadingFaceVaryingColor);
    bits.set(Osd::MeshEndCapBSplineBasis, g_endCap == kEndCapBSplineBasis);
    bits.set(Osd::MeshEndCapGregoryBasis, g_endCap == kEndCapGregoryBasis);
    bits.set(Osd::MeshEndCapLegacyGregory, g_endCap == kEndCapLegacyGregory);

    int numVertexElements = 3;
    int numVaryingElements =
        (g_shadingMode == kShadingVaryingColor || interleaveVarying) ? 4 : 0;


    if (kernel == kCPU) {
        g_mesh = new Osd::Mesh<Osd::CpuGLVertexBuffer,
                               Far::StencilTable,
                               Osd::CpuEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits);
#ifdef OPENSUBDIV_HAS_OPENMP
    } else if (kernel == kOPENMP) {
        g_mesh = new Osd::Mesh<Osd::CpuGLVertexBuffer,
                               Far::StencilTable,
                               Osd::OmpEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits);
#endif
#ifdef OPENSUBDIV_HAS_TBB
    } else if (kernel == kTBB) {
        g_mesh = new Osd::Mesh<Osd::CpuGLVertexBuffer,
                               Far::StencilTable,
                               Osd::TbbEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits);
#endif
#ifdef OPENSUBDIV_HAS_OPENCL
    } else if(kernel == kCL) {
        // CLKernel
        static Osd::EvaluatorCacheT<Osd::CLEvaluator> clEvaluatorCache;
        g_mesh = new Osd::Mesh<Osd::CLGLVertexBuffer,
                               Osd::CLStencilTable,
                               Osd::CLEvaluator,
                               Osd::GLPatchTable,
                               CLDeviceContext>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits,
                                   &clEvaluatorCache,
                                   &g_clDeviceContext);
#endif
#ifdef OPENSUBDIV_HAS_CUDA
    } else if(kernel == kCUDA) {
        g_mesh = new Osd::Mesh<Osd::CudaGLVertexBuffer,
                               Osd::CudaStencilTable,
                               Osd::CudaEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits);
#endif
#ifdef OPENSUBDIV_HAS_GLSL_TRANSFORM_FEEDBACK
    } else if(kernel == kGLSL) {
        static Osd::EvaluatorCacheT<Osd::GLXFBEvaluator> glXFBEvaluatorCache;
        g_mesh = new Osd::Mesh<Osd::GLVertexBuffer,
                               Osd::GLStencilTableTBO,
                               Osd::GLXFBEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits,
                                   &glXFBEvaluatorCache);
#endif
#ifdef OPENSUBDIV_HAS_GLSL_COMPUTE
    } else if(kernel == kGLSLCompute) {
        static Osd::EvaluatorCacheT<Osd::GLComputeEvaluator> glComputeEvaluatorCache;
        g_mesh = new Osd::Mesh<Osd::GLVertexBuffer,
                               Osd::GLStencilTableSSBO,
                               Osd::GLComputeEvaluator,
                               Osd::GLPatchTable>(
                                   refiner,
                                   numVertexElements,
                                   numVaryingElements,
                                   level, bits,
                                   &glComputeEvaluatorCache);


#endif
    } else {
        printf("Unsupported kernel %s\n", getKernelName(kernel));
    }

    if (g_shadingMode == kShadingFaceVaryingColor && shape->HasUV()) {

        std::vector<float> fvarData;

        InterpolateFVarData(*refiner, *shape, fvarData);

        // set fvardata to texture buffer
        g_fvarData.Create(g_mesh->GetFarPatchTable(),
                          shape->GetFVarWidth(), fvarData);
    }

    // legacy gregory
    delete g_legacyGregoryPatchTable;
    g_legacyGregoryPatchTable = NULL;
    if (g_endCap == kEndCapLegacyGregory) {
        g_legacyGregoryPatchTable =
            Osd::GLLegacyGregoryPatchTable::Create(g_mesh->GetFarPatchTable());
    }

    if (! doAnim) {
        delete shape;
    }

    // compute model bounding
    float min[3] = { FLT_MAX,  FLT_MAX,  FLT_MAX};
    float max[3] = {-FLT_MAX, -FLT_MAX, -FLT_MAX};
    for (size_t i=0; i <g_orgPositions.size()/3; ++i) {
        for(int j=0; j<3; ++j) {
            float v = g_orgPositions[i*3+j];
            min[j] = std::min(min[j], v);
            max[j] = std::max(max[j], v);
        }
    }
    for (int j=0; j<3; ++j) {
        g_center[j] = (min[j] + max[j]) * 0.5f;
        g_size += (max[j]-min[j])*(max[j]-min[j]);
    }
    g_size = sqrtf(g_size);

    g_tessLevelMin = 1;

    g_tessLevel = std::max(g_tessLevel,g_tessLevelMin);

    updateGeom();

    // -------- VAO
    glBindVertexArray(g_vao);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_mesh->GetPatchTable()->GetPatchIndexBuffer());
    glBindBuffer(GL_ARRAY_BUFFER, g_mesh->BindVertexBuffer());

    glEnableVertexAttribArray(0);

    if (g_shadingMode == kShadingVaryingColor) {
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 3, 0);
        glBindBuffer(GL_ARRAY_BUFFER, g_mesh->BindVaryingBuffer());
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 4, 0);
    } else if (g_shadingMode == kShadingInterleavedVaryingColor) {
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 7, 0);
        glEnableVertexAttribArray(1);
        glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 7, (void*)(sizeof (GLfloat) * 3));
    } else {
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 3, 0);
        glDisableVertexAttribArray(1);
    }

    glBindBuffer(GL_ARRAY_BUFFER, 0);
    glBindVertexArray(0);
}

//------------------------------------------------------------------------------
static void
fitFrame() {

    g_pan[0] = g_pan[1] = 0;
    g_dolly = g_size;
}

//------------------------------------------------------------------------------

union Effect {
    Effect(int displayStyle_, int shadingMode_, int screenSpaceTess_,
           int fractionalSpacing_, int patchCull_, int singleCreasePatch_)
        : value(0) {
        displayStyle = displayStyle_;
        shadingMode = shadingMode_;
        screenSpaceTess = screenSpaceTess_;
        fractionalSpacing = fractionalSpacing_;
        patchCull = patchCull_;
        singleCreasePatch = singleCreasePatch_;
    }

    struct {
        unsigned int displayStyle:2;
        unsigned int shadingMode:4;
        unsigned int screenSpaceTess:1;
        unsigned int fractionalSpacing:1;
        unsigned int patchCull:1;
        unsigned int singleCreasePatch:1;
    };
    int value;

    bool operator < (const Effect &e) const {
        return value < e.value;
    }
};

static Effect
GetEffect()
{
    return Effect(g_displayStyle,
                  g_shadingMode,
                  g_screenSpaceTess,
                  g_fractionalSpacing,
                  g_patchCull,
                  g_singleCreasePatch);
}

// ---------------------------------------------------------------------------

struct EffectDesc {
    EffectDesc(OpenSubdiv::Far::PatchDescriptor desc,
               Effect effect) : desc(desc), effect(effect),
                                maxValence(0), numElements(0) { }

    OpenSubdiv::Far::PatchDescriptor desc;
    Effect effect;
    int maxValence;
    int numElements;

    bool operator < (const EffectDesc &e) const {
        return
            (desc < e.desc || ((desc == e.desc &&
            (maxValence < e.maxValence || ((maxValence == e.maxValence) &&
            (numElements < e.numElements || ((numElements == e.numElements) &&
            (effect < e.effect))))))));
    }
};

// ---------------------------------------------------------------------------

class ShaderCache : public GLShaderCache<EffectDesc> {
public:
    virtual GLDrawConfig *CreateDrawConfig(EffectDesc const &effectDesc) {

        using namespace OpenSubdiv;

        // compile shader program

        GLDrawConfig *config = new GLDrawConfig(GLUtils::GetShaderVersionInclude().c_str());

        Far::PatchDescriptor::Type type = effectDesc.desc.GetType();

        // common defines
        std::stringstream ss;

        if (type == Far::PatchDescriptor::QUADS) {
            ss << "#define PRIM_QUAD\n";
        } else {
            ss << "#define PRIM_TRI\n";
        }

        // OSD tessellation controls
        if (effectDesc.effect.screenSpaceTess) {
            ss << "#define OSD_ENABLE_SCREENSPACE_TESSELLATION\n";
        }
        if (effectDesc.effect.fractionalSpacing) {
            ss << "#define OSD_FRACTIONAL_ODD_SPACING\n";
        }
        if (effectDesc.effect.patchCull) {
            ss << "#define OSD_ENABLE_PATCH_CULL\n";
        }
        if (effectDesc.effect.singleCreasePatch) {
            ss << "#define OSD_PATCH_ENABLE_SINGLE_CREASE\n";
        }
        // for legacy gregory
        ss << "#define OSD_MAX_VALENCE " << effectDesc.maxValence << "\n";
        ss << "#define OSD_NUM_ELEMENTS " << effectDesc.numElements << "\n";

        // display styles
        switch (effectDesc.effect.displayStyle) {
        case kDisplayStyleWire:
            ss << "#define GEOMETRY_OUT_WIRE\n";
            break;
        case kDisplayStyleWireOnShaded:
            ss << "#define GEOMETRY_OUT_LINE\n";
            break;
        case kDisplayStyleShaded:
            ss << "#define GEOMETRY_OUT_FILL\n";
            break;
        }

        // shading mode
        switch(effectDesc.effect.shadingMode) {
        case kShadingMaterial:
            ss << "#define SHADING_MATERIAL\n";
            break;
        case kShadingVaryingColor:
            ss << "#define SHADING_VARYING_COLOR\n";
            break;
        case kShadingInterleavedVaryingColor:
            ss << "#define SHADING_VARYING_COLOR\n";
            break;
        case kShadingFaceVaryingColor:
            ss << "#define OSD_FVAR_WIDTH 2\n";
            ss << "#define SHADING_FACEVARYING_COLOR\n";
            if (! effectDesc.desc.IsAdaptive()) {
                ss << "#define SHADING_FACEVARYING_UNIFORM_SUBDIVISION\n";
            }
            break;
        case kShadingPatchType:
            ss << "#define SHADING_PATCH_TYPE\n";
            break;
        case kShadingPatchCoord:
            ss << "#define SHADING_PATCH_COORD\n";
            break;
        case kShadingNormal:
            ss << "#define SHADING_NORMAL\n";
            break;
        }

        if (type == Far::PatchDescriptor::TRIANGLES) {
            ss << "#define LOOP\n";
        } else if (type == Far::PatchDescriptor::QUADS) {
        } else {
            ss << "#define SMOOTH_NORMALS\n";
        }

        // need for patch color-coding : we need these defines in the fragment shader
        if (type == Far::PatchDescriptor::GREGORY) {
            ss << "#define OSD_PATCH_GREGORY\n";
        } else if (type == Far::PatchDescriptor::GREGORY_BOUNDARY) {
            ss << "#define OSD_PATCH_GREGORY_BOUNDARY\n";
        } else if (type == Far::PatchDescriptor::GREGORY_BASIS) {
            ss << "#define OSD_PATCH_GREGORY_BASIS\n";
        }

        // include osd PatchCommon
        ss << "#define OSD_PATCH_BASIS_GLSL\n";
        ss << Osd::GLSLPatchShaderSource::GetPatchBasisShaderSource();
        ss << Osd::GLSLPatchShaderSource::GetCommonShaderSource();
        std::string common = ss.str();
        ss.str("");

        // vertex shader
        ss << common
            // enable local vertex shader
           << (effectDesc.desc.IsAdaptive() ? "" : "#define VERTEX_SHADER\n")
           << shaderSource()
           << Osd::GLSLPatchShaderSource::GetVertexShaderSource(type);
        config->CompileAndAttachShader(GL_VERTEX_SHADER, ss.str());
        ss.str("");

        if (effectDesc.desc.IsAdaptive()) {
            // tess control shader
            ss << common
                << shaderSource()
               << Osd::GLSLPatchShaderSource::GetTessControlShaderSource(type);
            config->CompileAndAttachShader(GL_TESS_CONTROL_SHADER, ss.str());
            ss.str("");

            // tess eval shader
            ss << common
                << shaderSource()
               << Osd::GLSLPatchShaderSource::GetTessEvalShaderSource(type);
            config->CompileAndAttachShader(GL_TESS_EVALUATION_SHADER, ss.str());
            ss.str("");
        }

        // geometry shader
        ss << common
           << "#define GEOMETRY_SHADER\n"
           << shaderSource();
        config->CompileAndAttachShader(GL_GEOMETRY_SHADER, ss.str());
        ss.str("");

        // fragment shader
        ss << common
           << "#define FRAGMENT_SHADER\n"
           << shaderSource();
        config->CompileAndAttachShader(GL_FRAGMENT_SHADER, ss.str());
        ss.str("");

        if (!config->Link()) {
            delete config;
            return NULL;
        }

        // assign uniform locations
        GLuint uboIndex;
        GLuint program = config->GetProgram();
        uboIndex = glGetUniformBlockIndex(program, "Transform");
        if (uboIndex != GL_INVALID_INDEX)
            glUniformBlockBinding(program, uboIndex, g_transformBinding);

        uboIndex = glGetUniformBlockIndex(program, "Tessellation");
        if (uboIndex != GL_INVALID_INDEX)
            glUniformBlockBinding(program, uboIndex, g_tessellationBinding);

        uboIndex = glGetUniformBlockIndex(program, "Lighting");
        if (uboIndex != GL_INVALID_INDEX)
            glUniformBlockBinding(program, uboIndex, g_lightingBinding);

        // assign texture locations
        GLint loc;
        glUseProgram(program);
        if ((loc = glGetUniformLocation(program, "OsdPatchParamBuffer")) != -1) {
            glUniform1i(loc, 0); // GL_TEXTURE0
        }
        if ((loc = glGetUniformLocation(program, "OsdFVarDataBuffer")) != -1) {
            glUniform1i(loc, 1); // GL_TEXTURE1
        }
        // for legacy gregory patches
        if ((loc = glGetUniformLocation(program, "OsdVertexBuffer")) != -1) {
            glUniform1i(loc, 2); // GL_TEXTURE2
        }
        if ((loc = glGetUniformLocation(program, "OsdValenceBuffer")) != -1) {
            glUniform1i(loc, 3); // GL_TEXTURE3
        }
        if ((loc = glGetUniformLocation(program, "OsdQuadOffsetBuffer")) != -1) {
            glUniform1i(loc, 4); // GL_TEXTURE4
        }
        glUseProgram(0);

        return config;
    }
};

ShaderCache g_shaderCache;

//------------------------------------------------------------------------------
static void
updateUniformBlocks() {
    if (! g_transformUB) {
        glGenBuffers(1, &g_transformUB);
        glBindBuffer(GL_UNIFORM_BUFFER, g_transformUB);
        glBufferData(GL_UNIFORM_BUFFER,
                sizeof(g_transformData), NULL, GL_STATIC_DRAW);
    };
    glBindBuffer(GL_UNIFORM_BUFFER, g_transformUB);
    glBufferSubData(GL_UNIFORM_BUFFER,
                0, sizeof(g_transformData), &g_transformData);
    glBindBuffer(GL_UNIFORM_BUFFER, 0);

    glBindBufferBase(GL_UNIFORM_BUFFER, g_transformBinding, g_transformUB);

    // Update and bind tessellation state
    struct Tessellation {
        float TessLevel;
    } tessellationData;

    tessellationData.TessLevel = static_cast<float>(1 << g_tessLevel);

    if (! g_tessellationUB) {
        glGenBuffers(1, &g_tessellationUB);
        glBindBuffer(GL_UNIFORM_BUFFER, g_tessellationUB);
        glBufferData(GL_UNIFORM_BUFFER,
                sizeof(tessellationData), NULL, GL_STATIC_DRAW);
    };
    glBindBuffer(GL_UNIFORM_BUFFER, g_tessellationUB);
    glBufferSubData(GL_UNIFORM_BUFFER,
                0, sizeof(tessellationData), &tessellationData);
    glBindBuffer(GL_UNIFORM_BUFFER, 0);

    glBindBufferBase(GL_UNIFORM_BUFFER, g_tessellationBinding, g_tessellationUB);

    // Update and bind lighting state
    struct Lighting {
        struct Light {
            float position[4];
            float ambient[4];
            float diffuse[4];
            float specular[4];
        } lightSource[2];
    } lightingData = {
       {{  { 0.5,  0.2f, 1.0f, 0.0f },
           { 0.1f, 0.1f, 0.1f, 1.0f },
           { 0.7f, 0.7f, 0.7f, 1.0f },
           { 0.8f, 0.8f, 0.8f, 1.0f } },

         { { -0.8f, 0.4f, -1.0f, 0.0f },
           {  0.0f, 0.0f,  0.0f, 1.0f },
           {  0.5f, 0.5f,  0.5f, 1.0f },
           {  0.8f, 0.8f,  0.8f, 1.0f } }}
    };
    if (! g_lightingUB) {
        glGenBuffers(1, &g_lightingUB);
        glBindBuffer(GL_UNIFORM_BUFFER, g_lightingUB);
        glBufferData(GL_UNIFORM_BUFFER,
                sizeof(lightingData), NULL, GL_STATIC_DRAW);
    };
    glBindBuffer(GL_UNIFORM_BUFFER, g_lightingUB);
    glBufferSubData(GL_UNIFORM_BUFFER,
                0, sizeof(lightingData), &lightingData);
    glBindBuffer(GL_UNIFORM_BUFFER, 0);

    glBindBufferBase(GL_UNIFORM_BUFFER, g_lightingBinding, g_lightingUB);
}

static void
bindTextures() {
    // bind patch textures
    if (g_mesh->GetPatchTable()->GetPatchParamTextureBuffer()) {
        glActiveTexture(GL_TEXTURE0);
        glBindTexture(GL_TEXTURE_BUFFER,
            g_mesh->GetPatchTable()->GetPatchParamTextureBuffer());
    }

    if (true) {
        glActiveTexture(GL_TEXTURE1);
        glBindTexture(GL_TEXTURE_BUFFER,
                      g_fvarData.textureBuffer);
    }

    // legacy gregory
    if (g_legacyGregoryPatchTable) {
        glActiveTexture(GL_TEXTURE2);
        glBindTexture(GL_TEXTURE_BUFFER,
                      g_legacyGregoryPatchTable->GetVertexTextureBuffer());
        glActiveTexture(GL_TEXTURE3);
        glBindTexture(GL_TEXTURE_BUFFER,
                      g_legacyGregoryPatchTable->GetVertexValenceTextureBuffer());
        glActiveTexture(GL_TEXTURE4);
        glBindTexture(GL_TEXTURE_BUFFER,
                      g_legacyGregoryPatchTable->GetQuadOffsetsTextureBuffer());
    }
    glActiveTexture(GL_TEXTURE0);
}

static GLenum
bindProgram(Effect effect,
            OpenSubdiv::Osd::PatchArray const & patch) {
    EffectDesc effectDesc(patch.GetDescriptor(), effect);

    // only legacy gregory needs maxValence and numElements
    // neither legacy gregory nor gregory basis need single crease
    typedef OpenSubdiv::Far::PatchDescriptor Descriptor;
    if (patch.GetDescriptor().GetType() == Descriptor::GREGORY ||
        patch.GetDescriptor().GetType() == Descriptor::GREGORY_BOUNDARY) {
        int maxValence = g_mesh->GetMaxValence();
        int numElements = (g_shadingMode == kShadingInterleavedVaryingColor ? 7 : 3);
        effectDesc.maxValence = maxValence;
        effectDesc.numElements = numElements;
        effectDesc.effect.singleCreasePatch = 0;
    }
    if (patch.GetDescriptor().GetType() == Descriptor::GREGORY_BASIS) {
        effectDesc.effect.singleCreasePatch = 0;
    }

    // lookup shader cache (compile the shader if needed)
    GLDrawConfig *config = g_shaderCache.GetDrawConfig(effectDesc);
    if (!config) return 0;

    GLuint program = config->GetProgram();

    glUseProgram(program);

    // bind standalone uniforms
    GLint uniformPrimitiveIdBase =
        glGetUniformLocation(program, "PrimitiveIdBase");
    if (uniformPrimitiveIdBase >=0)
        glUniform1i(uniformPrimitiveIdBase, patch.GetPrimitiveIdBase());

    // legacy gregory
    if (g_endCap == kEndCapLegacyGregory) {
        GLint uniformGregoryQuadOffsetBase =
            glGetUniformLocation(program, "GregoryQuadOffsetBase");
        int quadOffsetBase =
            g_legacyGregoryPatchTable->GetQuadOffsetsBase(patch.GetDescriptor().GetType());
        if (uniformGregoryQuadOffsetBase >= 0)
            glUniform1i(uniformGregoryQuadOffsetBase, quadOffsetBase);
    }

    // update uniform
    GLint uniformDiffuseColor =
        glGetUniformLocation(program, "diffuseColor");
    if (uniformDiffuseColor >= 0)
        glUniform4f(uniformDiffuseColor, 0.4f, 0.4f, 0.8f, 1);

    // return primtype
    GLenum primType;
    switch(effectDesc.desc.GetType()) {
    case Descriptor::QUADS:
        primType = GL_LINES_ADJACENCY;
        break;
    case Descriptor::TRIANGLES:
        primType = GL_TRIANGLES;
        break;
    default:
#if defined(GL_ARB_tessellation_shader) || defined(GL_VERSION_4_0)
        primType = GL_PATCHES;
        glPatchParameteri(GL_PATCH_VERTICES, effectDesc.desc.GetNumControlVertices());
#else
        primType = GL_POINTS;
#endif
        break;
    }

    return primType;
}

//------------------------------------------------------------------------------
static void
display() {
    Stopwatch s;
    s.Start();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glViewport(0, 0, g_width, g_height);
    g_hud.FillBackground();

    // prepare view matrix
    double aspect = g_width/(double)g_height;
    identity(g_transformData.ModelViewMatrix);
    translate(g_transformData.ModelViewMatrix, -g_pan[0], -g_pan[1], -g_dolly);
    rotate(g_transformData.ModelViewMatrix, g_rotate[1], 1, 0, 0);
    rotate(g_transformData.ModelViewMatrix, g_rotate[0], 0, 1, 0);
    rotate(g_transformData.ModelViewMatrix, -90, 1, 0, 0);
    translate(g_transformData.ModelViewMatrix,
              -g_center[0], -g_center[1], -g_center[2]);
    perspective(g_transformData.ProjectionMatrix,
                45.0f, (float)aspect, 0.1f, 500.0f);
    multMatrix(g_transformData.ModelViewProjectionMatrix,
               g_transformData.ModelViewMatrix,
               g_transformData.ProjectionMatrix);
    inverseMatrix(g_transformData.ModelViewInverseMatrix,
                  g_transformData.ModelViewMatrix);

    // make sure that the vertex buffer is interoped back as a GL resources.
    GLuint vbo = g_mesh->BindVertexBuffer();

    // vertex texture update for legacy gregory drawing
    if (g_legacyGregoryPatchTable) {
        glActiveTexture(GL_TEXTURE1);
        g_legacyGregoryPatchTable->UpdateVertexBuffer(vbo);
    }

    if (g_shadingMode == kShadingVaryingColor)
        g_mesh->BindVaryingBuffer();

    // update transform and lighting uniform blocks
    updateUniformBlocks();

    // also bind patch related textures
    bindTextures();

    if (g_displayStyle == kDisplayStyleWire)
        glDisable(GL_CULL_FACE);

    glEnable(GL_DEPTH_TEST);

    glBindVertexArray(g_vao);

    OpenSubdiv::Osd::PatchArrayVector const & patches =
        g_mesh->GetPatchTable()->GetPatchArrays();

    // patch drawing
    int patchCount[13]; // [Type] (see far/patchTable.h)
    int numTotalPatches = 0;
    int numDrawCalls = 0;
    memset(patchCount, 0, sizeof(patchCount));

    // primitive counting
    glBeginQuery(GL_PRIMITIVES_GENERATED, g_queries[0]);
#if defined(GL_VERSION_3_3)
    glBeginQuery(GL_TIME_ELAPSED, g_queries[1]);
#endif

    // core draw-calls
    for (int i=0; i<(int)patches.size(); ++i) {
        OpenSubdiv::Osd::PatchArray const & patch = patches[i];

        OpenSubdiv::Far::PatchDescriptor desc = patch.GetDescriptor();
        OpenSubdiv::Far::PatchDescriptor::Type patchType = desc.GetType();

        patchCount[patchType] += patch.GetNumPatches();
        numTotalPatches += patch.GetNumPatches();

        GLenum primType = bindProgram(GetEffect(), patch);


        glDrawElements(primType,
                       patch.GetNumPatches() * desc.GetNumControlVertices(),
                       GL_UNSIGNED_INT,
                       (void *)(patch.GetIndexBase() * sizeof(unsigned int)));
        ++numDrawCalls;
    }

    s.Stop();
    float drawCpuTime = float(s.GetElapsed() * 1000.0f);

    glEndQuery(GL_PRIMITIVES_GENERATED);
#if defined(GL_VERSION_3_3)
    glEndQuery(GL_TIME_ELAPSED);
#endif

    glBindVertexArray(0);

    glUseProgram(0);

    if (g_displayStyle == kDisplayStyleWire)
        glEnable(GL_CULL_FACE);

    // draw the control mesh
    int stride = g_shadingMode == kShadingInterleavedVaryingColor ? 7 : 3;
    g_controlMeshDisplay.Draw(vbo, stride*sizeof(float),
                              g_transformData.ModelViewProjectionMatrix);

    glBindBuffer(GL_ARRAY_BUFFER, 0);

    GLuint numPrimsGenerated = 0;
    GLuint timeElapsed = 0;
    glGetQueryObjectuiv(g_queries[0], GL_QUERY_RESULT, &numPrimsGenerated);
#if defined(GL_VERSION_3_3)
    glGetQueryObjectuiv(g_queries[1], GL_QUERY_RESULT, &timeElapsed);
#endif

    float drawGpuTime = timeElapsed / 1000.0f / 1000.0f;

    g_fpsTimer.Stop();
    float elapsed = (float)g_fpsTimer.GetElapsed();
    if (! g_freeze) {
        g_animTime += elapsed;
    }
    g_fpsTimer.Start();

    if (g_hud.IsVisible()) {

        typedef OpenSubdiv::Far::PatchDescriptor Descriptor;

        double fps = 1.0/elapsed;

        if (g_displayPatchCounts) {
            int x = -280;
            int y = -180;
            g_hud.DrawString(x, y, "NonPatch         : %d",
                             patchCount[Descriptor::QUADS]); y += 20;
            g_hud.DrawString(x, y, "Regular          : %d",
                             patchCount[Descriptor::REGULAR]); y+= 20;
            g_hud.DrawString(x, y, "Gregory          : %d",
                             patchCount[Descriptor::GREGORY]); y+= 20;
            g_hud.DrawString(x, y, "Boundary Gregory : %d",
                             patchCount[Descriptor::GREGORY_BOUNDARY]); y+= 20;
            g_hud.DrawString(x, y, "Gregory Basis    : %d",
                             patchCount[Descriptor::GREGORY_BASIS]); y+= 20;
        }

        int y = -220;
        g_hud.DrawString(10, y, "Tess level : %d", g_tessLevel); y+= 20;
        g_hud.DrawString(10, y, "Patches    : %d", numTotalPatches); y+= 20;
        g_hud.DrawString(10, y, "Draw calls : %d", numDrawCalls); y+= 20;
        g_hud.DrawString(10, y, "Primitives : %d", numPrimsGenerated); y+= 20;
        g_hud.DrawString(10, y, "Vertices   : %d", g_mesh->GetNumVertices()); y+= 20;
        g_hud.DrawString(10, y, "GPU Kernel : %.3f ms", g_gpuTime); y+= 20;
        g_hud.DrawString(10, y, "CPU Kernel : %.3f ms", g_cpuTime); y+= 20;
        g_hud.DrawString(10, y, "GPU Draw   : %.3f ms", drawGpuTime); y+= 20;
        g_hud.DrawString(10, y, "CPU Draw   : %.3f ms", drawCpuTime); y+= 20;
        g_hud.DrawString(10, y, "FPS        : %3.1f", fps); y+= 20;

        g_hud.Flush();
    }

    glFinish();

    GLUtils::CheckGLErrors("display leave\n");
}

//------------------------------------------------------------------------------
static void
motion(GLFWwindow *, double dx, double dy) {

    int x=(int)dx, y=(int)dy;

    if (g_hud.MouseCapture()) {
        // check gui
        g_hud.MouseMotion(x, y);
    } else if (g_mbutton[0] && !g_mbutton[1] && !g_mbutton[2]) {
        // orbit
        g_rotate[0] += x - g_prev_x;
        g_rotate[1] += y - g_prev_y;
    } else if (!g_mbutton[0] && !g_mbutton[1] && g_mbutton[2]) {
        // pan
        g_pan[0] -= g_dolly*(x - g_prev_x)/g_width;
        g_pan[1] += g_dolly*(y - g_prev_y)/g_height;
    } else if ((g_mbutton[0] && !g_mbutton[1] && g_mbutton[2]) ||
               (!g_mbutton[0] && g_mbutton[1] && !g_mbutton[2])) {
        // dolly
        g_dolly -= g_dolly*0.01f*(x - g_prev_x);
        if(g_dolly <= 0.01) g_dolly = 0.01f;
    }

    g_prev_x = x;
    g_prev_y = y;
}

//------------------------------------------------------------------------------
static void
mouse(GLFWwindow *, int button, int state, int /* mods */) {

    if (state == GLFW_RELEASE)
        g_hud.MouseRelease();

    if (button == 0 && state == GLFW_PRESS && g_hud.MouseClick(g_prev_x, g_prev_y))
        return;

    if (button < 3) {
        g_mbutton[button] = (state == GLFW_PRESS);
    }
}

//------------------------------------------------------------------------------
static void
uninitGL() {

    glDeleteQueries(2, g_queries);
    glDeleteVertexArrays(1, &g_vao);

    if (g_mesh)
        delete g_mesh;

    if (g_legacyGregoryPatchTable)
        delete g_legacyGregoryPatchTable;

}

//------------------------------------------------------------------------------
static void
reshape(GLFWwindow *, int width, int height) {

    g_width = width;
    g_height = height;

    int windowWidth = g_width, windowHeight = g_height;

    // window size might not match framebuffer size on a high DPI display
    glfwGetWindowSize(g_window, &windowWidth, &windowHeight);

    g_hud.Rebuild(windowWidth, windowHeight, width, height);
}

//------------------------------------------------------------------------------
void windowClose(GLFWwindow*) {
    g_running = false;
}

//------------------------------------------------------------------------------
static void
toggleFullScreen() {
    // XXXX manuelk : to re-implement from glut
}

//------------------------------------------------------------------------------
static void
keyboard(GLFWwindow *, int key, int /* scancode */, int event, int /* mods */) {

    if (event == GLFW_RELEASE) return;
    if (g_hud.KeyDown(tolower(key))) return;

    switch (key) {
        case 'Q': g_running = 0; break;
        case 'F': fitFrame(); break;
        case GLFW_KEY_TAB: toggleFullScreen(); break;
        case '+':
        case '=':  g_tessLevel++; break;
        case '-':  g_tessLevel = std::max(g_tessLevelMin, g_tessLevel-1); break;
        case GLFW_KEY_ESCAPE: g_hud.SetVisible(!g_hud.IsVisible()); break;
        case 'X': GLUtils::WriteScreenshot(g_width, g_height); break;
    }
}

//------------------------------------------------------------------------------
static void
callbackDisplayStyle(int b) {
    g_displayStyle = b;
}

static void
callbackShadingMode(int b) {
    if (g_shadingMode == kShadingVaryingColor || b == kShadingVaryingColor ||
        g_shadingMode == kShadingInterleavedVaryingColor || b == kShadingInterleavedVaryingColor ||
        g_shadingMode == kShadingFaceVaryingColor || b == kShadingFaceVaryingColor) {
        // need to rebuild for varying reconstruct
        g_shadingMode = b;
        rebuildMesh();
        return;
    }
    g_shadingMode = b;
}

static void
callbackEndCap(int endCap) {
    g_endCap = endCap;
    rebuildMesh();
}

static void
callbackKernel(int k) {
    g_kernel = k;

#ifdef OPENSUBDIV_HAS_OPENCL
    if (g_kernel == kCL && (!g_clDeviceContext.IsInitialized())) {
        if (g_clDeviceContext.Initialize() == false) {
            printf("Error in initializing OpenCL\n");
            exit(1);
        }
    }
#endif
#ifdef OPENSUBDIV_HAS_CUDA
    if (g_kernel == kCUDA && (!g_cudaDeviceContext.IsInitialized())) {
        if (g_cudaDeviceContext.Initialize() == false) {
            printf("Error in initializing Cuda\n");
            exit(1);
        }
    }
#endif

    rebuildMesh();
}

static void
callbackLevel(int l) {
    g_level = l;
    rebuildMesh();
}

static void
callbackModel(int m) {
    if (m < 0)
        m = 0;

    if (m >= (int)g_defaultShapes.size())
        m = (int)g_defaultShapes.size() - 1;

    g_currentShape = m;
    rebuildMesh();
}

static void
callbackCheckBox(bool checked, int button) {

    if (GLUtils::SupportsAdaptiveTessellation()) {
        switch(button) {
        case kHUD_CB_ADAPTIVE:
            g_adaptive = checked;
            rebuildMesh();
            return;
        case kHUD_CB_SINGLE_CREASE_PATCH:
            g_singleCreasePatch = checked;
            rebuildMesh();
            return;
        case kHUD_CB_INF_SHARP_PATCH:
            g_infSharpPatch = checked;
            rebuildMesh();
            return;
        default:
            break;
        }
    }

    switch (button) {
    case kHUD_CB_DISPLAY_CONTROL_MESH_EDGES:
        g_controlMeshDisplay.SetEdgesDisplay(checked);
        break;
    case kHUD_CB_DISPLAY_CONTROL_MESH_VERTS:
        g_controlMeshDisplay.SetVerticesDisplay(checked);
        break;
    case kHUD_CB_ANIMATE_VERTICES:
        g_moveScale = checked;
        break;
    case kHUD_CB_VIEW_LOD:
        g_screenSpaceTess = checked;
        break;
    case kHUD_CB_FRACTIONAL_SPACING:
        g_fractionalSpacing = checked;
        break;
    case kHUD_CB_PATCH_CULL:
        g_patchCull = checked;
        break;
    case kHUD_CB_FREEZE:
        g_freeze = checked;
        break;
    case kHUD_CB_DISPLAY_PATCH_COUNTS:
        g_displayPatchCounts = checked;
        break;
    }
}

static void
initHUD() {
    int windowWidth = g_width, windowHeight = g_height;
    int frameBufferWidth = g_width, frameBufferHeight = g_height;

    // window size might not match framebuffer size on a high DPI display
    glfwGetWindowSize(g_window, &windowWidth, &windowHeight);
    glfwGetFramebufferSize(g_window, &frameBufferWidth, &frameBufferHeight);

    g_hud.Init(windowWidth, windowHeight, frameBufferWidth, frameBufferHeight);

    int y = 10;
    g_hud.AddCheckBox("Control edges (H)",
                      g_controlMeshDisplay.GetEdgesDisplay(),
                      10, y, callbackCheckBox,
                      kHUD_CB_DISPLAY_CONTROL_MESH_EDGES, 'h');
    y += 20;
    g_hud.AddCheckBox("Control vertices (J)",
                      g_controlMeshDisplay.GetVerticesDisplay(),
                      10, y, callbackCheckBox,
                      kHUD_CB_DISPLAY_CONTROL_MESH_VERTS, 'j');
    y += 20;
    g_hud.AddCheckBox("Animate vertices (M)", g_moveScale != 0,
                      10, y, callbackCheckBox, kHUD_CB_ANIMATE_VERTICES, 'm');
    y += 20;
    g_hud.AddCheckBox("Screen space LOD (V)",  g_screenSpaceTess != 0,
                      10, y, callbackCheckBox, kHUD_CB_VIEW_LOD, 'v');
    y += 20;
    g_hud.AddCheckBox("Fractional spacing (T)",  g_fractionalSpacing != 0,
                      10, y, callbackCheckBox, kHUD_CB_FRACTIONAL_SPACING, 't');
    y += 20;
    g_hud.AddCheckBox("Frustum Patch Culling (B)",  g_patchCull != 0,
                      10, y, callbackCheckBox, kHUD_CB_PATCH_CULL, 'b');
    y += 20;
    g_hud.AddCheckBox("Freeze (spc)", g_freeze != 0,
                      10, y, callbackCheckBox, kHUD_CB_FREEZE, ' ');
    y += 20;

    int displaystyle_pulldown = g_hud.AddPullDown("DisplayStyle (W)", 200, 10, 250,
                                                  callbackDisplayStyle, 'w');
    g_hud.AddPullDownButton(displaystyle_pulldown, "Wire", kDisplayStyleWire,
                            g_displayStyle == kDisplayStyleWire);
    g_hud.AddPullDownButton(displaystyle_pulldown, "Shaded", kDisplayStyleShaded,
                            g_displayStyle == kDisplayStyleShaded);
    g_hud.AddPullDownButton(displaystyle_pulldown, "Wire+Shaded", kDisplayStyleWireOnShaded,
                            g_displayStyle == kDisplayStyleWireOnShaded);

    int shading_pulldown = g_hud.AddPullDown("Shading (C)", 200, 70, 250,
                                             callbackShadingMode, 'c');
    g_hud.AddPullDownButton(shading_pulldown, "Material",
                            kShadingMaterial,
                            g_shadingMode == kShadingMaterial);
    g_hud.AddPullDownButton(shading_pulldown, "Varying Color",
                            kShadingVaryingColor,
                            g_shadingMode == kShadingVaryingColor);
    g_hud.AddPullDownButton(shading_pulldown, "Varying Color (Interleaved)",
                            kShadingInterleavedVaryingColor,
                            g_shadingMode == kShadingInterleavedVaryingColor);
    g_hud.AddPullDownButton(shading_pulldown, "FaceVarying Color",
                            kShadingFaceVaryingColor,
                            g_shadingMode == kShadingFaceVaryingColor);
    g_hud.AddPullDownButton(shading_pulldown, "Patch Type",
                            kShadingPatchType,
                            g_shadingMode == kShadingPatchType);
    g_hud.AddPullDownButton(shading_pulldown, "Patch Coord",
                            kShadingPatchCoord,
                            g_shadingMode == kShadingPatchCoord);
    g_hud.AddPullDownButton(shading_pulldown, "Normal",
                            kShadingNormal,
                            g_shadingMode == kShadingNormal);

    int compute_pulldown = g_hud.AddPullDown("Compute (K)", 475, 10, 300, callbackKernel, 'k');
    g_hud.AddPullDownButton(compute_pulldown, "CPU", kCPU);
#ifdef OPENSUBDIV_HAS_OPENMP
    g_hud.AddPullDownButton(compute_pulldown, "OpenMP", kOPENMP);
#endif
#ifdef OPENSUBDIV_HAS_TBB
    g_hud.AddPullDownButton(compute_pulldown, "TBB", kTBB);
#endif
#ifdef OPENSUBDIV_HAS_CUDA
    g_hud.AddPullDownButton(compute_pulldown, "CUDA", kCUDA);
#endif
#ifdef OPENSUBDIV_HAS_OPENCL
    if (CLDeviceContext::HAS_CL_VERSION_1_1()) {
        g_hud.AddPullDownButton(compute_pulldown, "OpenCL", kCL);
    }
#endif
#ifdef OPENSUBDIV_HAS_GLSL_TRANSFORM_FEEDBACK
    g_hud.AddPullDownButton(compute_pulldown, "GLSL TransformFeedback", kGLSL);
#endif
#ifdef OPENSUBDIV_HAS_GLSL_COMPUTE
    if (GLUtils::GL_ARBComputeShaderOrGL_VERSION_4_3()) {
        g_hud.AddPullDownButton(compute_pulldown, "GLSL Compute", kGLSLCompute);
    }
#endif
    if (GLUtils::SupportsAdaptiveTessellation()) {
        g_hud.AddCheckBox("Adaptive (`)", g_adaptive!=0,
                          10, 190, callbackCheckBox, kHUD_CB_ADAPTIVE, '`');
        g_hud.AddCheckBox("Single Crease Patch (S)", g_singleCreasePatch!=0,
                          10, 210, callbackCheckBox, kHUD_CB_SINGLE_CREASE_PATCH, 's');
        g_hud.AddCheckBox("Inf Sharp Patch (I)", g_infSharpPatch!=0,
                          10, 230, callbackCheckBox, kHUD_CB_INF_SHARP_PATCH, 'i');

        int endcap_pulldown = g_hud.AddPullDown(
            "End cap (E)", 10, 250, 200, callbackEndCap, 'e');
        g_hud.AddPullDownButton(endcap_pulldown,"None",
                                kEndCapNone,
                                g_endCap == kEndCapNone);
        g_hud.AddPullDownButton(endcap_pulldown, "BSpline",
                                kEndCapBSplineBasis,
                                g_endCap == kEndCapBSplineBasis);
        g_hud.AddPullDownButton(endcap_pulldown, "GregoryBasis",
                                kEndCapGregoryBasis,
                                g_endCap == kEndCapGregoryBasis);
        g_hud.AddPullDownButton(endcap_pulldown, "LegacyGregory",
                                kEndCapLegacyGregory,
                                g_endCap == kEndCapLegacyGregory);
    }

    for (int i = 1; i < 11; ++i) {
        char level[16];
        sprintf(level, "Lv. %d", i);
        g_hud.AddRadioButton(3, level, i==2, 10, 310+i*20, callbackLevel, i, '0'+(i%10));
    }

    int shapes_pulldown = g_hud.AddPullDown("Shape (N)", -300, 10, 300, callbackModel, 'n');
    for (int i = 0; i < (int)g_defaultShapes.size(); ++i) {
        g_hud.AddPullDownButton(shapes_pulldown, g_defaultShapes[i].name.c_str(),i);
    }

    g_hud.AddCheckBox("Show patch counts", g_displayPatchCounts!=0, -280, -20, callbackCheckBox, kHUD_CB_DISPLAY_PATCH_COUNTS);

    g_hud.Rebuild(windowWidth, windowHeight, frameBufferWidth, frameBufferHeight);
}

//------------------------------------------------------------------------------
static void
initGL() {
    glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glCullFace(GL_BACK);
    glEnable(GL_CULL_FACE);

    glGenQueries(2, g_queries);

    glGenVertexArrays(1, &g_vao);
}

//------------------------------------------------------------------------------
static void
idle() {

    if (! g_freeze) {
        g_frame++;
        updateGeom();
    }

    if (g_repeatCount != 0 && g_frame >= g_repeatCount)
        g_running = 0;
}

//------------------------------------------------------------------------------
static void
callbackErrorOsd(OpenSubdiv::Far::ErrorType err, const char *message) {
    printf("Error: %d\n", err);
    printf("%s", message);
}

//------------------------------------------------------------------------------
static void
callbackErrorGLFW(int error, const char* description) {
    fprintf(stderr, "GLFW Error (%d) : %s\n", error, description);
}
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
int main(int argc, char ** argv) {

    bool fullscreen = false;
    std::string str;
    std::vector<char const *> animobjs;

    for (int i = 1; i < argc; ++i) {
        if (strstr(argv[i], ".obj")) {
            animobjs.push_back(argv[i]);
        }
        else if (!strcmp(argv[i], "-axis")) {
            g_axis = false;
        }
        else if (!strcmp(argv[i], "-d")) {
            g_level = atoi(argv[++i]);
        }
        else if (!strcmp(argv[i], "-c")) {
            g_repeatCount = atoi(argv[++i]);
        }
        else if (!strcmp(argv[i], "-f")) {
            fullscreen = true;
        }
        else {
            std::ifstream ifs(argv[1]);
            if (ifs) {
                std::stringstream ss;
                ss << ifs.rdbuf();
                ifs.close();
                str = ss.str();
                g_defaultShapes.push_back(ShapeDesc(argv[1], str.c_str(), kCatmark));
            }
        }
    }

    if (! animobjs.empty()) {

        g_defaultShapes.push_back(ShapeDesc(animobjs[0], "", kCatmark));

        g_objAnim = ObjAnim::Create(animobjs, g_axis);
    }

    initShapes();

    g_fpsTimer.Start();

    OpenSubdiv::Far::SetErrorCallback(callbackErrorOsd);

    glfwSetErrorCallback(callbackErrorGLFW);
    if (! glfwInit()) {
        printf("Failed to initialize GLFW\n");
        return 1;
    }

    static const char windowTitle[] = "OpenSubdiv glViewer " OPENSUBDIV_VERSION_STRING;

    GLUtils::SetMinimumGLVersion(argc, argv);

    if (fullscreen) {

        g_primary = glfwGetPrimaryMonitor();

        // apparently glfwGetPrimaryMonitor fails under linux : if no primary,
        // settle for the first one in the list
        if (! g_primary) {
            int count = 0;
            GLFWmonitor ** monitors = glfwGetMonitors(&count);

            if (count)
                g_primary = monitors[0];
        }

        if (g_primary) {
            GLFWvidmode const * vidmode = glfwGetVideoMode(g_primary);
            g_width = vidmode->width;
            g_height = vidmode->height;
        }
    }

    g_window = glfwCreateWindow(g_width, g_height, windowTitle,
        fullscreen && g_primary ? g_primary : NULL, NULL);

    if (! g_window) {
        std::cerr << "Failed to create OpenGL context.\n";
        glfwTerminate();
        return 1;
    }

    glfwMakeContextCurrent(g_window);
    GLUtils::PrintGLVersion();

    // accommocate high DPI displays (e.g. mac retina displays)
    glfwGetFramebufferSize(g_window, &g_width, &g_height);
    glfwSetFramebufferSizeCallback(g_window, reshape);

    glfwSetKeyCallback(g_window, keyboard);
    glfwSetCursorPosCallback(g_window, motion);
    glfwSetMouseButtonCallback(g_window, mouse);
    glfwSetWindowCloseCallback(g_window, windowClose);

#if defined(OSD_USES_GLEW)
#ifdef CORE_PROFILE
    // this is the only way to initialize glew correctly under core profile context.
    glewExperimental = true;
#endif
    if (GLenum r = glewInit() != GLEW_OK) {
        printf("Failed to initialize glew. Error = %s\n", glewGetErrorString(r));
        exit(1);
    }
#ifdef CORE_PROFILE
    // clear GL errors which was generated during glewInit()
    glGetError();
#endif
#endif

    // activate feature adaptive tessellation if OSD supports it
    g_adaptive = GLUtils::SupportsAdaptiveTessellation();

    initGL();

    glfwSwapInterval(0);

    initHUD();
    rebuildMesh();

    while (g_running) {
        idle();
        display();

        glfwPollEvents();
        glfwSwapBuffers(g_window);

        glFinish();
    }

    uninitGL();
    glfwTerminate();
}

//------------------------------------------------------------------------------