OpenSubdiv/opensubdiv/osd/glslPatchRegular.glsl

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#extension GL_EXT_gpu_shader4 : require
#line 2

//----------------------------------------------------------
// Patches.TessVertex
//----------------------------------------------------------
#ifdef PATCH_VERTEX_SHADER

layout (location=0) in vec4 position;

out block {
    ControlVertex v;
} output;

void main() {
    output.v.position = ModelViewMatrix * position;
    OSD_PATCH_CULL_COMPUTE_CLIPFLAGS(position);

#if OSD_NUM_VARYINGS > 0
    for (int i = 0; i < OSD_NUM_VARYINGS; ++i)
        output.v.varyings[i] = varyings[i];
#endif
}

#endif

//----------------------------------------------------------
// Patches.TessControlRegular
//----------------------------------------------------------
#ifdef PATCH_TESS_CONTROL_REGULAR_SHADER

layout(vertices = 16) out;

in block {
    ControlVertex v;
} input[];

out block {
    ControlVertex v;
} output[];

uniform isamplerBuffer g_patchLevelBuffer;
OSD_DECLARE_PTEX_INDICES_BUFFER;

#define ID gl_InvocationID

void main()
{
    int i = ID/4;
    int j = ID%4;

    vec3 H[4];
    for (int l=0; l<4; l++) {
        H[l] = vec3(0,0,0);
        for (int k=0; k<4; k++) {
            float c = Q[i][k];
            // XXX: fix this in patchMeshFactory.
//            H[l] += c*input[l*4 + k].v.position.xyz;
            H[l] += c*input[l + k*4].v.position.xyz;
        }
    }

    vec3 pos = vec3(0,0,0);
    for (int k=0; k<4; k++) {
        pos += Q[j][k]*H[k];
    }

    output[ID].v.position = vec4(pos, 1.0);

    int patchLevel = texelFetchBuffer(g_patchLevelBuffer, gl_PrimitiveID + LevelBase).x;
    // +0.5 to avoid interpolation error of integer value
    output[ID].v.patchCoord = vec4(0, 0,
                                   patchLevel+0.5,
                                   gl_PrimitiveID+LevelBase+0.5);

    OSD_COMPUTE_PTEX_COORD_TESSCONTROL_SHADER;

    if (ID == 0) {
        OSD_PATCH_CULL(16);

#if OSD_ENABLE_SCREENSPACE_TESSELLATION
        gl_TessLevelOuter[0] =
            TessAdaptive(input[5].v.position.xyz, input[9].v.position.xyz, patchLevel);
        gl_TessLevelOuter[1] =
            TessAdaptive(input[5].v.position.xyz, input[6].v.position.xyz, patchLevel);
        gl_TessLevelOuter[2] =
            TessAdaptive(input[6].v.position.xyz, input[10].v.position.xyz, patchLevel);
        gl_TessLevelOuter[3] =
            TessAdaptive(input[9].v.position.xyz, input[10].v.position.xyz, patchLevel);
        gl_TessLevelInner[0] =
            max(gl_TessLevelOuter[1], gl_TessLevelOuter[3]);
        gl_TessLevelInner[1] =
            max(gl_TessLevelOuter[0], gl_TessLevelOuter[2]);
#else
        gl_TessLevelInner[0] = GetTessLevel(patchLevel);
        gl_TessLevelInner[1] = GetTessLevel(patchLevel);
        gl_TessLevelOuter[0] = GetTessLevel(patchLevel);
        gl_TessLevelOuter[1] = GetTessLevel(patchLevel);
        gl_TessLevelOuter[2] = GetTessLevel(patchLevel);
        gl_TessLevelOuter[3] = GetTessLevel(patchLevel);
#endif
    }
}

#endif

//----------------------------------------------------------
// Patches.TessEvalRegular
//----------------------------------------------------------
#ifdef PATCH_TESS_EVAL_REGULAR_SHADER

layout(quads) in;
layout(equal_spacing) in;

in block {
    ControlVertex v;
} input[];

out block {
    OutputVertex v;
} output;

void main()
{
    float u = gl_TessCoord.x,
          v = gl_TessCoord.y;

    vec3 WorldPos, Tangent, BiTangent;
    vec3 cp[16];
    for(int i = 0; i < 16; ++i) cp[i] = input[i].v.position.xyz;
    EvalBSpline(gl_TessCoord.xy, cp, WorldPos, Tangent, BiTangent);

    vec3 normal = normalize(cross(Tangent, BiTangent));

    output.v.position = vec4(WorldPos, 1.0f);
    output.v.normal = normal;
    output.v.tangent = Tangent;

    output.v.patchCoord = input[0].v.patchCoord;
    output.v.patchCoord.xy = vec2(u, v);

    OSD_COMPUTE_PTEX_COORD_TESSEVAL_SHADER;

    OSD_DISPLACEMENT_CALLBACK;

    gl_Position = (ProjectionMatrix * vec4(WorldPos, 1.0f));
}

#endif

//----------------------------------------------------------
// Patches.Vertex
//----------------------------------------------------------
#ifdef VERTEX_SHADER

layout (location=0) in vec4 position;
layout (location=1) in vec3 normal;
layout (location=2) in vec4 color;

out block {
    OutputVertex v;
} output;

void main() {
    gl_Position = ModelViewProjectionMatrix * position;
    output.v.color = color;
}

#endif

//----------------------------------------------------------
// Patches.FragmentColor
//----------------------------------------------------------
#ifdef FRAGMENT_SHADER

in block {
    OutputVertex v;
} input;

void main() {
    gl_FragColor = input.v.color;
}
#endif