//
//   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.
//

#if defined(__APPLE__)
    #if defined(OSD_USES_GLEW)
        #include <GL/glew.h>
    #else
        #include <OpenGL/gl3.h>
    #endif
    #define GLFW_INCLUDE_GL3
    #define GLFW_NO_GLU
#else
    #include <stdlib.h>
    #include <GL/glew.h>
    #if defined(WIN32)
        #include <GL/wglew.h>
    #endif
#endif

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

#include <osd/cpuComputeContext.h>
#include <osd/cpuComputeController.h>
#include <osd/cpuEvalLimitContext.h>
#include <osd/cpuEvalLimitController.h>
#include <osd/cpuVertexBuffer.h>
#include <osd/cpuGLVertexBuffer.h>
#include <osd/error.h>
#include <osd/drawContext.h>
#include <osd/mesh.h>
#include <osd/vertex.h>

#include <common/vtr_utils.h>
#include "../common/stopwatch.h"
#include "../common/simple_math.h"
#include "../common/gl_hud.h"

#include "init_shapes.h"
#include "particles.h"

#include <cfloat>
#include <vector>
#include <iostream>
#include <fstream>
#include <sstream>
#include <stdlib.h>

#ifdef OPENSUBDIV_HAS_OPENMP
    #include <omp.h>
#endif

using namespace OpenSubdiv;

//------------------------------------------------------------------------------
std::vector<float> g_orgPositions,
                   g_positions,
                   g_varyingColors;

int g_currentShape = 0,
    g_level = 3,
    g_numElements = 3;

std::vector<int>   g_coarseEdges;
std::vector<float> g_coarseEdgeSharpness;
std::vector<float> g_coarseVertexSharpness;

enum DrawMode { kRANDOM=0,
                kUV=1,
                kVARYING=2,
                kFACEVARYING=3 };

int   g_running = 1,
      g_width = 1024,
      g_height = 1024,
      g_fullscreen = 0,
      g_drawCageEdges = 1,
      g_drawCageVertices = 1,
      g_drawMode = kVARYING,
      g_prev_x = 0,
      g_prev_y = 0,
      g_mbutton[3] = {0, 0, 0},
      g_frame=0,
      g_freeze=0,
      g_repeatCount;

float g_rotate[2] = {0, 0},
      g_dolly = 5,
      g_pan[2] = {0, 0},
      g_center[3] = {0, 0, 0},
      g_size = 0,
      g_moveScale = 0.0f;

GLuint g_transformUB = 0,
       g_transformBinding = 0;

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


// performance
float g_evalTime = 0;
float g_computeTime = 0;
Stopwatch g_fpsTimer;

//------------------------------------------------------------------------------
int g_nparticles=0,
    g_nsamples=101,
    g_nsamplesFound=0;

bool g_randomStart=true;

GLuint g_cageEdgeVAO = 0,
       g_cageEdgeVBO = 0,
       g_cageVertexVAO = 0,
       g_cageVertexVBO = 0,
       g_samplesVAO=0;

GLhud g_hud;

//------------------------------------------------------------------------------
static void
createRandomColors(int nverts, int stride, float * colors) {

    // large Pell prime number
    srand( static_cast<int>(2147483647) );

    for (int i=0; i<nverts; ++i) {
        colors[i*stride+0] = (float)rand()/(float)RAND_MAX;
        colors[i*stride+1] = (float)rand()/(float)RAND_MAX;
        colors[i*stride+2] = (float)rand()/(float)RAND_MAX;
    }
}

//------------------------------------------------------------------------------
static void
createCoarseMesh(OpenSubdiv::Far::TopologyRefiner const & refiner) {

    typedef OpenSubdiv::Far::IndexArray IndexArray;

    // save coarse topology (used for coarse mesh drawing)
    int nedges = refiner.GetNumEdges(0),
        nverts = refiner.GetNumVertices(0);

    g_coarseEdges.resize(nedges*2);
    g_coarseEdgeSharpness.resize(nedges);
    g_coarseVertexSharpness.resize(nverts);

    for(int i=0; i<nedges; ++i) {
        IndexArray verts = refiner.GetEdgeVertices(0, i);
        g_coarseEdges[i*2  ]=verts[0];
        g_coarseEdges[i*2+1]=verts[1];
        g_coarseEdgeSharpness[i]=refiner.GetEdgeSharpness(0, i);
    }

    for(int i=0; i<nverts; ++i) {
        g_coarseVertexSharpness[i]=refiner.GetVertexSharpness(0, i);
    }

    // assign a randomly generated color for each vertex ofthe mesh
    g_varyingColors.resize(nverts*3);
    createRandomColors(nverts, 3, &g_varyingColors[0]);
}

//------------------------------------------------------------------------------
Far::TopologyRefiner * g_topologyRefiner = 0;

Osd::CpuVertexBuffer * g_vertexData = 0,
                   * g_varyingData = 0;

Osd::CpuComputeContext * g_computeCtx = 0;

Osd::CpuComputeController g_computeCtrl;

Far::KernelBatchVector  g_kernelBatches;

Osd::CpuEvalLimitContext * g_evalCtx = 0;

Osd::CpuEvalLimitController g_evalCtrl;

Osd::VertexBufferDescriptor g_idesc( /*offset*/ 0, /*legnth*/ 3, /*stride*/ 3 ),
                          g_odesc( /*offset*/ 0, /*legnth*/ 3, /*stride*/ 6 ),
                          g_vdesc( /*offset*/ 3, /*legnth*/ 3, /*stride*/ 6 ),
                          g_fvidesc( /*offset*/ 0, /*legnth*/ 2, /*stride*/ 2 ),
                          g_fvodesc( /*offset*/ 3, /*legnth*/ 2, /*stride*/ 6 );


Osd::CpuGLVertexBuffer * g_Q=0,
                     * g_dQs=0,
                     * g_dQt=0;

STParticles * g_particles=0;

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

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

    const float *p = &g_orgPositions[0];

    float r = sin(g_frame*0.001f) * g_moveScale;

    for (int i = 0; i < nverts; ++i) {
        //float move = 0.05f*cosf(p[0]*20+g_frame*0.01f);
        float ct = cos(p[2] * r);
        float st = sin(p[2] * r);
        g_positions[i*3+0] = p[0]*ct + p[1]*st;
        g_positions[i*3+1] = -p[0]*st + p[1]*ct;
        g_positions[i*3+2] = p[2];
        p+=3;
    }

    // Run Compute pass to pose the control vertices ---------------------------
    Stopwatch s;
    s.Start();

    g_vertexData->UpdateData( &g_positions[0], 0, nverts);

    g_computeCtrl.Compute(g_computeCtx, g_kernelBatches, g_vertexData, g_varyingData);

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


    // Run Eval pass to get the samples locations ------------------------------

    s.Start();

    // The varying data ends-up interleaved in the same g_Q output buffer because
    // g_Q has a stride of 6 and g_vdesc sets the offset to 3, while g_odesc sets
    // the offset to 0
    switch (g_drawMode) {
        case kVARYING     : g_evalCtrl.BindVaryingBuffers( g_idesc, g_varyingData, g_vdesc, g_Q ); break;

        case kFACEVARYING : //g_evalCtrl.BindFacevaryingBuffers( g_fvidesc, g_fvodesc, g_Q ); break;
        case kRANDOM      :
        case kUV          :
        default : g_evalCtrl.Unbind(); break;
    }

    // Bind/Unbind of the vertex buffers to the context needs to happen
    // outside of the parallel loop
    g_evalCtrl.BindVertexBuffers( g_idesc, g_vertexData, g_odesc, g_Q, g_dQs, g_dQt );


    // Apply 'dynamics' update
    assert(g_particles);
    g_particles->Update(g_evalTime); // XXXX g_evalTime is not really elapsed time...


    // Evaluate the positions of the samples on the limit surface
    g_nsamplesFound=0;
#define USE_OPENMP
#if defined(OPENSUBDIV_HAS_OPENMP) and defined(USE_OPENMP)
    #pragma omp parallel for
#endif
    for (int i=0; i<g_nparticles; ++i) {

        Osd::LimitLocation & coord = g_particles->GetPositions()[i];

        int n = g_evalCtrl.EvalLimitSample( coord, g_evalCtx, i );

        if (n) {
            // point colors
            switch (g_drawMode) {
                case kUV : { float * color = g_Q->BindCpuBuffer() + i*g_Q->GetNumElements()  + 3;
                             color[0] = coord.s;
                             color[1] = 0.0f;
                             color[2] = coord.t; } break;

                case kRANDOM : // no update needed
                case kVARYING : 
                case kFACEVARYING : break;

                default : break;
           }
#if defined(OPENSUBDIV_HAS_OPENMP) and defined(USE_OPENMP)
            #pragma omp atomic
#endif
            g_nsamplesFound += n;
        } else {
            // "hide" unfound samples (hole tags...) as a black dot at the origin
            float * sample = g_Q->BindCpuBuffer() + i*g_Q->GetNumElements();
            memset(sample, 0, g_Q->GetNumElements() * sizeof(float));
        }
    }

    g_evalCtrl.Unbind();

    g_Q->BindVBO();

    s.Stop();

    g_evalTime = float(s.GetElapsed());
}

//------------------------------------------------------------------------------
static void
createOsdMesh(ShapeDesc const & shapeDesc, int level) {


    Shape * shape = Shape::parseObj(shapeDesc.data.c_str(), shapeDesc.scheme);

    // create Vtr mesh (topology)
    OpenSubdiv::Sdc::Type       sdctype = GetSdcType(*shape);
    OpenSubdiv::Sdc::Options sdcoptions = GetSdcOptions(*shape);

    delete g_topologyRefiner;
    OpenSubdiv::Far::TopologyRefiner * g_topologyRefiner =
        OpenSubdiv::Far::TopologyRefinerFactory<Shape>::Create(sdctype, sdcoptions, *shape);

    g_orgPositions=shape->verts;
    g_positions.resize(g_orgPositions.size(), 0.0f);

    delete shape;

    float speed = g_particles ? g_particles->GetSpeed() : 0.2f;

    // Create the 'uv particles' manager - this class manages the limit
    // location samples (ptex face index, (s,t) and updates them between frames.
    // Note: the number of limit locations can be entirely arbitrary
    delete g_particles;
    g_particles = new STParticles(*g_topologyRefiner, g_nsamples, g_randomStart);
    g_nparticles = g_particles->GetNumParticles();
    g_particles->SetSpeed(speed);

    createCoarseMesh(*g_topologyRefiner);

    int nverts=0;
    {
        // Apply feature adaptive refinement to the mesh so that we can use the
        // limit evaluation API features.
        g_topologyRefiner->RefineAdaptive(level);

        nverts = g_topologyRefiner->GetNumVerticesTotal();

        // Generate stencil tables to update the bi-cubic patches control
        // vertices after they have been re-posed (both for vertex & varying
        // interpolation)
        Far::StencilTablesFactory::Options soptions;
        soptions.generateOffsets=true;
        soptions.generateIntermediateLevels=true;

        Far::StencilTables const * vertexStencils =
            Far::StencilTablesFactory::Create(*g_topologyRefiner, soptions);

        soptions.interpolationMode = Far::StencilTablesFactory::INTERPOLATE_VARYING;
        Far::StencilTables const * varyingStencils =
            Far::StencilTablesFactory::Create(*g_topologyRefiner, soptions);

        g_kernelBatches.clear();
        g_kernelBatches.push_back(Far::StencilTablesFactory::Create(*vertexStencils));

        // Create an Osd Compute context, used to "pose" the vertices with
        // the stencils tables
        delete g_computeCtx;
        g_computeCtx = Osd::CpuComputeContext::Create(vertexStencils, varyingStencils);


        // Generate bi-cubic patch tables for the limit surface
        Far::PatchTablesFactory::Options poptions;
        poptions.adaptiveStencilTables = vertexStencils;
        Far::PatchTables const * patchTables =
             Far::PatchTablesFactory::Create(*g_topologyRefiner, poptions);

        // Create a limit Eval context with the patch tables
        delete g_evalCtx;
        g_evalCtx = Osd::CpuEvalLimitContext::Create(*patchTables);
    }

    {   // Create vertex primvar buffer for the CVs
        delete g_vertexData;
        g_vertexData = Osd::CpuVertexBuffer::Create(3, nverts);

        // Create varying primvar buffer for the CVs with random colors.
        // These are immediately interpolated (once) and saved for display.
        delete g_varyingData; g_varyingData = 0;
        if (g_drawMode==kVARYING) {
            g_varyingData = Osd::CpuVertexBuffer::Create(3, nverts);
            g_varyingData->UpdateData( &g_varyingColors[0], 0, nverts);
        }

        // Create output buffers for the limit samples (position & tangents)
        delete g_Q;
        g_Q = Osd::CpuGLVertexBuffer::Create(6, g_nparticles);
        memset( g_Q->BindCpuBuffer(), 0, g_nparticles*6*sizeof(float));
        if (g_drawMode==kRANDOM) {
            createRandomColors(g_nparticles, 6, g_Q->BindCpuBuffer()+3);
        }

        delete g_dQs;
        g_dQs = Osd::CpuGLVertexBuffer::Create(6,g_nparticles);
        memset( g_dQs->BindCpuBuffer(), 0, g_nparticles*6*sizeof(float));

        delete g_dQt;
        g_dQt = Osd::CpuGLVertexBuffer::Create(6,g_nparticles);
        memset( g_dQt->BindCpuBuffer(), 0, g_nparticles*6*sizeof(float));
    }

    updateGeom();

    // Bind g_Q as a GL_POINTS VBO
    glBindVertexArray(g_samplesVAO);

    glBindBuffer(GL_ARRAY_BUFFER, g_Q->BindVBO());

    glEnableVertexAttribArray(0);
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, 0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, (float*)12);

    glBindVertexArray(0);
}

//------------------------------------------------------------------------------
struct Program
{
    GLuint program;
    GLuint uniformModelViewProjectionMatrix;
    GLuint attrPosition;
    GLuint attrColor;
} g_defaultProgram;

//------------------------------------------------------------------------------
static void
checkGLErrors(std::string const & where = "")
{
    GLuint err;
    while ((err = glGetError()) != GL_NO_ERROR) {

        std::cerr << "GL error: "
                  << (where.empty() ? "" : where + " ")
                  << err << "\n";
    }
}

//------------------------------------------------------------------------------
static GLuint
compileShader(GLenum shaderType, const char *source)
{
    GLuint shader = glCreateShader(shaderType);
    glShaderSource(shader, 1, &source, NULL);
    glCompileShader(shader);
    checkGLErrors("compileShader");
    return shader;
}

//------------------------------------------------------------------------------
static bool
linkDefaultProgram()
{
#if defined(GL_ARB_tessellation_shader) || defined(GL_VERSION_4_0)
    #define GLSL_VERSION_DEFINE "#version 400\n"
#else
    #define GLSL_VERSION_DEFINE "#version 150\n"
#endif

    static const char *vsSrc =
        GLSL_VERSION_DEFINE
        "in vec3 position;\n"
        "in vec3 color;\n"
        "out vec4 fragColor;\n"
        "uniform mat4 ModelViewProjectionMatrix;\n"
        "void main() {\n"
        "  fragColor = vec4(color, 1);\n"
        "  gl_Position = ModelViewProjectionMatrix * "
        "                  vec4(position, 1);\n"
        "}\n";

    static const char *fsSrc =
        GLSL_VERSION_DEFINE
        "in vec4 fragColor;\n"
        "out vec4 color;\n"
        "void main() {\n"
        "  color = fragColor;\n"
        "}\n";

    GLuint program = glCreateProgram();
    GLuint vertexShader = compileShader(GL_VERTEX_SHADER, vsSrc);
    GLuint fragmentShader = compileShader(GL_FRAGMENT_SHADER, fsSrc);

    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);

    glBindAttribLocation(program, 0, "position");
    glBindAttribLocation(program, 1, "color");
    glBindFragDataLocation(program, 0, "color");

    glLinkProgram(program);

    GLint status;
    glGetProgramiv(program, GL_LINK_STATUS, &status);
    if (status == GL_FALSE) {
        GLint infoLogLength;
        glGetProgramiv(program, GL_INFO_LOG_LENGTH, &infoLogLength);
        char *infoLog = new char[infoLogLength];
        glGetProgramInfoLog(program, infoLogLength, NULL, infoLog);
        printf("%s\n", infoLog);
        delete[] infoLog;
        exit(1);
    }

    g_defaultProgram.program = program;
    g_defaultProgram.uniformModelViewProjectionMatrix =
        glGetUniformLocation(program, "ModelViewProjectionMatrix");
    g_defaultProgram.attrPosition = glGetAttribLocation(program, "position");
    g_defaultProgram.attrColor = glGetAttribLocation(program, "color");

    return true;
}

//------------------------------------------------------------------------------
static inline void
setSharpnessColor(float s, float *r, float *g, float *b)
{
    //  0.0       2.0       4.0
    // green --- yellow --- red
    *r = std::min(1.0f, s * 0.5f);
    *g = std::min(1.0f, 2.0f - s*0.5f);
    *b = 0;
}

//------------------------------------------------------------------------------
static void
drawCageEdges() {

    glUseProgram(g_defaultProgram.program);
    glUniformMatrix4fv(g_defaultProgram.uniformModelViewProjectionMatrix,
                       1, GL_FALSE, g_transformData.ModelViewProjectionMatrix);

    std::vector<float> vbo;
    vbo.reserve(g_coarseEdges.size() * 6);
    float r, g, b;
    for (int i = 0; i < (int)g_coarseEdges.size(); i+=2) {
        setSharpnessColor(g_coarseEdgeSharpness[i/2], &r, &g, &b);
        for (int j = 0; j < 2; ++j) {
            vbo.push_back(g_positions[g_coarseEdges[i+j]*3]);
            vbo.push_back(g_positions[g_coarseEdges[i+j]*3+1]);
            vbo.push_back(g_positions[g_coarseEdges[i+j]*3+2]);
            vbo.push_back(r);
            vbo.push_back(g);
            vbo.push_back(b);
        }
    }

    glBindVertexArray(g_cageEdgeVAO);

    glBindBuffer(GL_ARRAY_BUFFER, g_cageEdgeVBO);
    glBufferData(GL_ARRAY_BUFFER, (int)vbo.size() * sizeof(float), &vbo[0],
                 GL_STATIC_DRAW);

    glEnableVertexAttribArray(g_defaultProgram.attrPosition);
    glEnableVertexAttribArray(g_defaultProgram.attrColor);
    glVertexAttribPointer(g_defaultProgram.attrPosition,
                          3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, 0);
    glVertexAttribPointer(g_defaultProgram.attrColor,
                          3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, (void*)12);

    glDrawArrays(GL_LINES, 0, (int)g_coarseEdges.size());

    glBindVertexArray(0);
    glUseProgram(0);
}

//------------------------------------------------------------------------------
static void
drawCageVertices() {

    glUseProgram(g_defaultProgram.program);
    glUniformMatrix4fv(g_defaultProgram.uniformModelViewProjectionMatrix,
                       1, GL_FALSE, g_transformData.ModelViewProjectionMatrix);

    int numPoints = (int)g_positions.size()/3;
    std::vector<float> vbo;
    vbo.reserve(numPoints*6);
    float r, g, b;
    for (int i = 0; i < numPoints; ++i) {

        switch (g_drawMode) {

            case kVARYING : { r=g_varyingColors[i*3+0];
                              g=g_varyingColors[i*3+1];
                              b=g_varyingColors[i*3+2];
                            } break;

            case kUV      : { setSharpnessColor(g_coarseVertexSharpness[i], &r, &g, &b);
                            } break;

            default : break;
        }

        vbo.push_back(g_positions[i*3+0]);
        vbo.push_back(g_positions[i*3+1]);
        vbo.push_back(g_positions[i*3+2]);
        vbo.push_back(r);
        vbo.push_back(g);
        vbo.push_back(b);
    }

    glBindVertexArray(g_cageVertexVAO);

    glBindBuffer(GL_ARRAY_BUFFER, g_cageVertexVBO);
    glBufferData(GL_ARRAY_BUFFER, (int)vbo.size() * sizeof(float), &vbo[0],
                 GL_STATIC_DRAW);

    glEnableVertexAttribArray(g_defaultProgram.attrPosition);
    glEnableVertexAttribArray(g_defaultProgram.attrColor);
    glVertexAttribPointer(g_defaultProgram.attrPosition,
                          3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, 0);
    glVertexAttribPointer(g_defaultProgram.attrColor,
                          3, GL_FLOAT, GL_FALSE, sizeof (GLfloat) * 6, (void*)12);

    glPointSize(10.0f);
    glDrawArrays(GL_POINTS, 0, numPoints);
    glPointSize(1.0f);

    glBindVertexArray(0);
    glUseProgram(0);
}

//------------------------------------------------------------------------------
static void
drawSamples() {

    glUseProgram(g_defaultProgram.program);

    glUniformMatrix4fv(g_defaultProgram.uniformModelViewProjectionMatrix,
                       1, GL_FALSE, g_transformData.ModelViewProjectionMatrix);


    glBindVertexArray(g_samplesVAO);

    glPointSize(2.0f);
    glDrawArrays(GL_POINTS, 0, g_nparticles);
    glPointSize(1.0f);

    glBindVertexArray(0);

    glUseProgram(0);
}

//------------------------------------------------------------------------------
static void
display() {

    g_hud.GetFrameBuffer()->Bind();

    Stopwatch s;
    s.Start();

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glViewport(0, 0, g_width, g_height);

    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, 0.01f, 500.0f);
    multMatrix(g_transformData.ModelViewProjectionMatrix,
               g_transformData.ModelViewMatrix,
               g_transformData.ProjectionMatrix);

    glEnable(GL_DEPTH_TEST);

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

    drawSamples();

    if (g_drawCageEdges)
        drawCageEdges();

    if (g_drawCageVertices)
        drawCageVertices();

    g_hud.GetFrameBuffer()->ApplyImageShader();

    if (g_hud.IsVisible()) {
        g_fpsTimer.Stop();
        double fps = 1.0/g_fpsTimer.GetElapsed();
        g_fpsTimer.Start();

        g_hud.DrawString(10, -150, "Particle Speed ([) (]): %.1f", g_particles->GetSpeed());
        g_hud.DrawString(10, -120, "# Samples  : (%d/%d)", g_nsamplesFound, g_Q->GetNumVertices());
        g_hud.DrawString(10, -100, "Compute    : %.3f ms", g_computeTime);
        g_hud.DrawString(10, -80,  "Eval       : %.3f ms", g_evalTime * 1000.f);
        g_hud.DrawString(10, -60,  "GPU Draw   : %.3f ms", drawGpuTime);
        g_hud.DrawString(10, -40,  "CPU Draw   : %.3f ms", drawCpuTime);
        g_hud.DrawString(10, -20,  "FPS        : %3.1f", fps);

        if (g_drawMode==kFACEVARYING and g_evalCtx->GetFVarData().empty()) {
            static char msg[21] = "No Face-Varying Data";
            g_hud.DrawString(g_width/2-20/2*8, g_height/2, msg);
        }

        g_hud.Flush();
    }

    glFinish();

    checkGLErrors("display leave");
}

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

    if (not g_freeze)
        g_frame++;

    updateGeom();

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

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

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

    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]) or
               (!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 (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
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
setSamples(bool add) {
    g_nsamples += add ? 50 : -50;

    g_nsamples = std::max(0, g_nsamples);

    createOsdMesh(g_defaultShapes[g_currentShape], g_level);
}

//------------------------------------------------------------------------------
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 '=': setSamples(true); break;

        case '-': setSamples(false); break;

        case '[': if (g_particles) { 
                      g_particles->SetSpeed(g_particles->GetSpeed()-0.1f);
                  } break;
        case ']': if (g_particles) { 
                      g_particles->SetSpeed(g_particles->GetSpeed()+0.1f);
                  } break;

        case GLFW_KEY_ESCAPE: g_hud.SetVisible(!g_hud.IsVisible()); break;
    }
}

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

//------------------------------------------------------------------------------
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;
    createOsdMesh(g_defaultShapes[g_currentShape], g_level);
}

//------------------------------------------------------------------------------
static void
callbackLevel(int l) {
    g_level = l;
    createOsdMesh(g_defaultShapes[g_currentShape], g_level);
}

//------------------------------------------------------------------------------
static void
callbackAnimate(bool checked, int /* m */) {
    g_moveScale = checked * 3.0f;
}

//------------------------------------------------------------------------------
static void
callbackFreeze(bool checked, int /* f */) {
    g_freeze = checked;
}

//------------------------------------------------------------------------------
static void
callbackCentered(bool checked, int /* f */) {
    g_randomStart = !checked;
    createOsdMesh(g_defaultShapes[g_currentShape], g_level);
}

//------------------------------------------------------------------------------
static void
callbackDisplayCageVertices(bool checked, int /* d */) {
    g_drawCageVertices = checked;
}

//------------------------------------------------------------------------------
static void
callbackDisplayCageEdges(bool checked, int /* d */) {
    g_drawCageEdges = checked;
}

//------------------------------------------------------------------------------
static void
callbackDisplayVaryingColors(int mode) {
    g_drawMode = mode;
    createOsdMesh(g_defaultShapes[g_currentShape], g_level);
}


//------------------------------------------------------------------------------
static void
initHUD() {
    int windowWidth = g_width, windowHeight = g_height,
        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);

    g_hud.SetFrameBuffer(new GLFrameBuffer);

    g_hud.AddCheckBox("Cage Edges (H)", true, 10, 10, callbackDisplayCageEdges, 0, 'h');
    g_hud.AddCheckBox("Cage Verts (J)", true, 10, 30, callbackDisplayCageVertices, 0, 'j');
    g_hud.AddCheckBox("Animate vertices (M)", g_moveScale != 0, 10, 50, callbackAnimate, 0, 'm');
    g_hud.AddCheckBox("Freeze (spc)", false, 10, 70, callbackFreeze, 0, ' ');

    g_hud.AddCheckBox("Random Start", false, 10, 120, callbackCentered, 0);

    int shading_pulldown = g_hud.AddPullDown("Shading (W)", 250, 10, 250, callbackDisplayVaryingColors, 'w');
    g_hud.AddPullDownButton(shading_pulldown, "Random", kRANDOM, g_drawMode==kRANDOM);
    g_hud.AddPullDownButton(shading_pulldown, "(u,v)", kUV, g_drawMode==kUV);
    g_hud.AddPullDownButton(shading_pulldown, "Varying", kVARYING, g_drawMode==kVARYING);
    g_hud.AddPullDownButton(shading_pulldown, "FaceVarying", kFACEVARYING, g_drawMode==kFACEVARYING);

    for (int i = 1; i < 11; ++i) {
        char level[16];
        sprintf(level, "Lv. %d", i);
        g_hud.AddRadioButton(3, level, i==g_level, 10, 170+i*20, callbackLevel, i, '0'+(i%10));
    }

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

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

//------------------------------------------------------------------------------
static void
initGL() {

    glClearColor(0.1f, 0.1f, 0.1f, 0.0f);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);
    glCullFace(GL_BACK);
    glEnable(GL_CULL_FACE);

    glGenVertexArrays(1, &g_cageVertexVAO);
    glGenVertexArrays(1, &g_cageEdgeVAO);
    glGenVertexArrays(1, &g_samplesVAO);
    glGenBuffers(1, &g_cageVertexVBO);
    glGenBuffers(1, &g_cageEdgeVBO);
}

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

    glDeleteBuffers(1, &g_cageVertexVBO);
    glDeleteBuffers(1, &g_cageEdgeVBO);
    glDeleteVertexArrays(1, &g_cageVertexVAO);
    glDeleteVertexArrays(1, &g_cageEdgeVAO);
    glDeleteVertexArrays(1, &g_samplesVAO);
}

//------------------------------------------------------------------------------
static void
setGLCoreProfile() {

    #define glfwOpenWindowHint glfwWindowHint
    #define GLFW_OPENGL_VERSION_MAJOR GLFW_CONTEXT_VERSION_MAJOR
    #define GLFW_OPENGL_VERSION_MINOR GLFW_CONTEXT_VERSION_MINOR

    glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#if not defined(__APPLE__)
    glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 4);
    glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
#else
    glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
    glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
#endif
    glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
}

//------------------------------------------------------------------------------
int main(int argc, char **argv) {

    bool fullscreen = false;

    std::string str;
    for (int i = 1; i < argc; ++i) {
        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));
            }
        }
    }

    Osd::SetErrorCallback(callbackError);


    initShapes();

    if (not glfwInit()) {
        printf("Failed to initialize GLFW\n");
        return 1;
    }

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

#define CORE_PROFILE
#ifdef CORE_PROFILE
    setGLCoreProfile();
#endif

    if (fullscreen) {

        g_primary = glfwGetPrimaryMonitor();

        // apparently glfwGetPrimaryMonitor fails under linux : if no primary,
        // settle for the first one in the list
        if (not 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;
        }
    }

    if (not (g_window=glfwCreateWindow(g_width, g_height, windowTitle,
                                       fullscreen and g_primary ? g_primary : NULL, NULL))) {
        printf("Failed to open window.\n");
        glfwTerminate();
        return 1;
    }
    glfwMakeContextCurrent(g_window);

    // accommodate 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

    //std::string & data = g_defaultShapes[ g_currentShape ].data;
    //Scheme scheme = g_defaultShapes[ g_currentShape ].scheme;

    //createOsdMesh( data, g_level, scheme );

    initGL();
    linkDefaultProgram();

    glfwSwapInterval(0);

    initHUD();
    callbackModel(g_currentShape);

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

        glfwPollEvents();
        glfwSwapBuffers(g_window);

        glFinish();
    }

    uninitGL();
    glfwTerminate();
}