//
//   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.
//

//----------------------------------------------------------
// Patches.VertexBSpline
//----------------------------------------------------------
#ifdef OSD_PATCH_VERTEX_BSPLINE_SHADER

layout(location = 0) in vec4 position;
OSD_USER_VARYING_ATTRIBUTE_DECLARE

out block {
    ControlVertex v;
    OSD_USER_VARYING_DECLARE
} outpt;

void main()
{
    outpt.v.position = position;
    OSD_PATCH_CULL_COMPUTE_CLIPFLAGS(position);
    OSD_USER_VARYING_PER_VERTEX();
}

#endif

//----------------------------------------------------------
// Patches.TessControlBSpline
//----------------------------------------------------------
#ifdef OSD_PATCH_TESS_CONTROL_BSPLINE_SHADER

patch out vec4 tessOuterLo, tessOuterHi;

in block {
    ControlVertex v;
    OSD_USER_VARYING_DECLARE
} inpt[];

out block {
    OsdPerPatchVertexBezier v;
    OSD_USER_VARYING_DECLARE
} outpt[16];

layout(vertices = 16) out;

void main()
{
    vec3 cv[16];
    for (int i=0; i<16; ++i) {
        cv[i] = inpt[i].v.position.xyz;
    }

    ivec3 patchParam = OsdGetPatchParam(OsdGetPatchIndex(gl_PrimitiveID));
    OsdComputePerPatchVertexBSpline(patchParam, gl_InvocationID, cv, outpt[gl_InvocationID].v);

    OSD_USER_VARYING_PER_CONTROL_POINT(gl_InvocationID, gl_InvocationID);

#if defined OSD_ENABLE_SCREENSPACE_TESSELLATION
    // Wait for all basis conversion to be finished
    barrier();
#endif
    if (gl_InvocationID == 0) {
        vec4 tessLevelOuter = vec4(0);
        vec2 tessLevelInner = vec2(0);

        OSD_PATCH_CULL(16);

#if defined OSD_ENABLE_SCREENSPACE_TESSELLATION
        // Gather bezier control points to compute limit surface tess levels
        OsdPerPatchVertexBezier cpBezier[16];
#if 0
        // XXX: this doesn't work on nvidia driver 34x.
        for (int i=0; i<16; ++i) {
            cpBezier[i] = outpt[i].v;
        }
#else
        cpBezier[0] = outpt[0].v;
        cpBezier[1] = outpt[1].v;
        cpBezier[2] = outpt[2].v;
        cpBezier[3] = outpt[3].v;
        cpBezier[4] = outpt[4].v;
        cpBezier[5] = outpt[5].v;
        cpBezier[6] = outpt[6].v;
        cpBezier[7] = outpt[7].v;
        cpBezier[8] = outpt[8].v;
        cpBezier[9] = outpt[9].v;
        cpBezier[10] = outpt[10].v;
        cpBezier[11] = outpt[11].v;
        cpBezier[12] = outpt[12].v;
        cpBezier[13] = outpt[13].v;
        cpBezier[14] = outpt[14].v;
        cpBezier[15] = outpt[15].v;
#endif
        OsdEvalPatchBezierTessLevels(cpBezier, patchParam,
                         tessLevelOuter, tessLevelInner,
                         tessOuterLo, tessOuterHi);
#else
        OsdGetTessLevelsUniform(patchParam, tessLevelOuter, tessLevelInner,
                         tessOuterLo, tessOuterHi);
#endif

        gl_TessLevelOuter[0] = tessLevelOuter[0];
        gl_TessLevelOuter[1] = tessLevelOuter[1];
        gl_TessLevelOuter[2] = tessLevelOuter[2];
        gl_TessLevelOuter[3] = tessLevelOuter[3];

        gl_TessLevelInner[0] = tessLevelInner[0];
        gl_TessLevelInner[1] = tessLevelInner[1];
    }
}

#endif

//----------------------------------------------------------
// Patches.TessEvalBSpline
//----------------------------------------------------------
#ifdef OSD_PATCH_TESS_EVAL_BSPLINE_SHADER

layout(quads) in;
layout(OSD_SPACING) in;

patch in vec4 tessOuterLo, tessOuterHi;

in block {
    OsdPerPatchVertexBezier v;
    OSD_USER_VARYING_DECLARE
} inpt[];

out block {
    OutputVertex v;
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
    vec2 vSegments;
#endif
    OSD_USER_VARYING_DECLARE
} outpt;

void main()
{
    vec3 P = vec3(0), dPu = vec3(0), dPv = vec3(0);
    vec3 N = vec3(0), dNu = vec3(0), dNv = vec3(0);

    OsdPerPatchVertexBezier cv[16];
    for (int i = 0; i < 16; ++i) {
        cv[i] = inpt[i].v;
    }

    vec2 UV = OsdGetTessParameterization(gl_TessCoord.xy,
                                         tessOuterLo,
                                         tessOuterHi);

    ivec3 patchParam = inpt[0].v.patchParam;
    OsdEvalPatchBezier(patchParam, UV, cv, P, dPu, dPv, N, dNu, dNv);

    // all code below here is client code
    outpt.v.position = OsdModelViewMatrix() * vec4(P, 1.0f);
    outpt.v.normal = (OsdModelViewMatrix() * vec4(N, 0.0f)).xyz;
    outpt.v.tangent = (OsdModelViewMatrix() * vec4(dPu, 0.0f)).xyz;
    outpt.v.bitangent = (OsdModelViewMatrix() * vec4(dPv, 0.0f)).xyz;
#ifdef OSD_COMPUTE_NORMAL_DERIVATIVES
    outpt.v.Nu = dNu;
    outpt.v.Nv = dNv;
#endif
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
    outpt.vSegments = cv[0].vSegments;
#endif

    outpt.v.tessCoord = UV;
    outpt.v.patchCoord = OsdInterpolatePatchCoord(UV, patchParam);

    OSD_USER_VARYING_PER_EVAL_POINT(UV, 5, 6, 9, 10);

    OSD_DISPLACEMENT_CALLBACK;

    gl_Position = OsdProjectionMatrix() * outpt.v.position;
}

#endif