//
//   Copyright 2013 Pixar
//
//   Licensed under the terms set forth in the LICENSE.txt file available at
//   https://opensubdiv.org/license.
//

#undef OSD_USER_VARYING_DECLARE
#define OSD_USER_VARYING_DECLARE \
    vec3 color;

#undef OSD_USER_VARYING_ATTRIBUTE_DECLARE
#define OSD_USER_VARYING_ATTRIBUTE_DECLARE \
    layout(location = 1) in vec3 color;

#undef OSD_USER_VARYING_PER_VERTEX
#define OSD_USER_VARYING_PER_VERTEX() \
    outpt.color = color

#undef OSD_USER_VARYING_PER_CONTROL_POINT
#define OSD_USER_VARYING_PER_CONTROL_POINT(ID_OUT, ID_IN) \
    outpt[ID_OUT].color = inpt[ID_IN].color

#undef OSD_USER_VARYING_PER_EVAL_POINT
#define OSD_USER_VARYING_PER_EVAL_POINT(UV, a, b, c, d) \
    outpt.color = \
        mix(mix(inpt[a].color, inpt[b].color, UV.x), \
            mix(inpt[c].color, inpt[d].color, UV.x), UV.y)

//--------------------------------------------------------------
// Uniform Blocks
//--------------------------------------------------------------

layout(std140) uniform Transform {
    mat4 ModelViewMatrix;
    mat4 ProjectionMatrix;
    mat4 ModelViewProjectionMatrix;
    mat4 ModelViewInverseMatrix;
    mat4 UvViewMatrix;
};

layout(std140) uniform Tessellation {
    float TessLevel;
};

uniform int GregoryQuadOffsetBase;
uniform int PrimitiveIdBase;

//--------------------------------------------------------------
// Osd external functions
//--------------------------------------------------------------

mat4 OsdModelViewMatrix()
{
    return ModelViewMatrix;
}
mat4 OsdProjectionMatrix()
{
    return ProjectionMatrix;
}
mat4 OsdModelViewProjectionMatrix()
{
    return ModelViewProjectionMatrix;
}
float OsdTessLevel()
{
    return TessLevel;
}
int OsdGregoryQuadOffsetBase()
{
    return GregoryQuadOffsetBase;
}
int OsdPrimitiveIdBase()
{
    return PrimitiveIdBase;
}
int OsdBaseVertex()
{
    return 0;
}

//--------------------------------------------------------------
// Vertex Shader
//--------------------------------------------------------------
#ifdef VERTEX_SHADER

layout (location=0) in vec4 position;
OSD_USER_VARYING_ATTRIBUTE_DECLARE

out block {
    OutputVertex v;
    OSD_USER_VARYING_DECLARE
} outpt;

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

    // We don't actually want to write all these, but some
    // compilers complain during about failing to fully write
    // outpt.v if they are excluded.
    outpt.v.normal = vec3(0);
    outpt.v.tangent = vec3(0);
    outpt.v.bitangent = vec3(0);
    outpt.v.patchCoord = vec4(0);
    outpt.v.tessCoord = vec2(0);
#if defined OSD_COMPUTE_NORMAL_DERIVATIVES
    outpt.v.Nu = vec3(0);
    outpt.v.Nv = vec3(0);
#endif
    // --

    OSD_USER_VARYING_PER_VERTEX();
}

#endif

//--------------------------------------------------------------
// Geometry Shader
//--------------------------------------------------------------
#ifdef GEOMETRY_SHADER

#ifdef PRIM_QUAD

    layout(lines_adjacency) in;

    #define EDGE_VERTS 4

#endif // PRIM_QUAD

#ifdef  PRIM_TRI

    layout(triangles) in;

    #define EDGE_VERTS 3

#endif // PRIM_TRI


layout(triangle_strip, max_vertices = EDGE_VERTS) out;
in block {
    OutputVertex v;
    OSD_USER_VARYING_DECLARE
} inpt[EDGE_VERTS];

out block {
    OutputVertex v;
    noperspective out vec4 edgeDistance;
    OSD_USER_VARYING_DECLARE
} outpt;

uniform isamplerBuffer OsdFVarParamBuffer;
layout(std140) uniform OsdFVarArrayData {
    OsdPatchArray fvarPatchArray[2];
};

vec2
interpolateFaceVarying(vec2 uv, int fvarOffset)
{
    int patchIndex = OsdGetPatchIndex(gl_PrimitiveID);

    OsdPatchArray array = fvarPatchArray[0];

    ivec3 fvarPatchParam = texelFetch(OsdFVarParamBuffer, patchIndex).xyz;
    OsdPatchParam param = OsdPatchParamInit(fvarPatchParam.x,
                                            fvarPatchParam.y,
                                            fvarPatchParam.z);

    int patchType = OsdPatchParamIsRegular(param) ? array.regDesc : array.desc;

    float wP[20], wDu[20], wDv[20], wDuu[20], wDuv[20], wDvv[20];
    int numPoints = OsdEvaluatePatchBasisNormalized(patchType, param,
                uv.s, uv.t, wP, wDu, wDv, wDuu, wDuv, wDvv);

    int primOffset = patchIndex * array.stride;

    vec2 result = vec2(0);
    for (int i=0; i<numPoints; ++i) {
        int index = (primOffset+i)*OSD_FVAR_WIDTH + fvarOffset;
        vec2 cv = vec2(texelFetch(OsdFVarDataBuffer, index).s,
                       texelFetch(OsdFVarDataBuffer, index + 1).s);
        result += wP[i] * cv;
    }

    return result;
}

void emit(int index, vec3 normal)
{
    outpt.v.position = inpt[index].v.position;
#ifdef SMOOTH_NORMALS
    outpt.v.normal = inpt[index].v.normal;
#else
    outpt.v.normal = normal;
#endif

#ifdef SHADING_FACEVARYING_UNIFORM_SUBDIVISION
    // interpolate fvar data at refined tri or quad vertex locations
#ifdef PRIM_TRI
    vec2 trist[3] = vec2[](vec2(0,0), vec2(1,0), vec2(0,1));
    vec2 st = trist[index];
#endif
#ifdef PRIM_QUAD
    vec2 quadst[4] = vec2[](vec2(0,0), vec2(1,0), vec2(1,1), vec2(0,1));
    vec2 st = quadst[index];
#endif
#else
    // interpolate fvar data at tessellated vertex locations
    vec2 st = inpt[index].v.tessCoord;
#endif

    vec2 uv = interpolateFaceVarying(st, /*fvarOffset*/0);

    outpt.color = vec3(uv.s, uv.t, 0);

#ifdef GEOMETRY_UV_VIEW
    uv = 2 * uv - vec2(1);
    gl_Position = UvViewMatrix * vec4(uv.s, uv.y, 0, 1);
#else
    gl_Position = ProjectionMatrix * inpt[index].v.position;
#endif
    EmitVertex();
}

#if defined(GEOMETRY_OUT_WIRE) || defined(GEOMETRY_OUT_LINE)
const float VIEWPORT_SCALE = 512.0;

float edgeDistance(vec4 p, vec4 p0, vec4 p1)
{
    return VIEWPORT_SCALE *
        abs((p.x - p0.x) * (p1.y - p0.y) -
            (p.y - p0.y) * (p1.x - p0.x)) / length(p1.xy - p0.xy);
}

void emit(int index, vec3 normal, vec4 edgeVerts[EDGE_VERTS])
{
    outpt.edgeDistance[0] =
        edgeDistance(edgeVerts[index], edgeVerts[0], edgeVerts[1]);
    outpt.edgeDistance[1] =
        edgeDistance(edgeVerts[index], edgeVerts[1], edgeVerts[2]);
#ifdef PRIM_TRI
    outpt.edgeDistance[2] =
        edgeDistance(edgeVerts[index], edgeVerts[2], edgeVerts[0]);
#endif
#ifdef PRIM_QUAD
    outpt.edgeDistance[2] =
        edgeDistance(edgeVerts[index], edgeVerts[2], edgeVerts[3]);
    outpt.edgeDistance[3] =
        edgeDistance(edgeVerts[index], edgeVerts[3], edgeVerts[0]);
#endif

    emit(index, normal);
}
#endif

void main()
{
    gl_PrimitiveID = gl_PrimitiveIDIn;

#ifdef PRIM_QUAD
    vec3 A = (inpt[0].v.position - inpt[1].v.position).xyz;
    vec3 B = (inpt[3].v.position - inpt[1].v.position).xyz;
    vec3 C = (inpt[2].v.position - inpt[1].v.position).xyz;
    vec3 n0 = normalize(cross(B, A));

#if defined(GEOMETRY_OUT_WIRE) || defined(GEOMETRY_OUT_LINE)
    vec4 edgeVerts[EDGE_VERTS];
    edgeVerts[0] = ProjectionMatrix * inpt[0].v.position;
    edgeVerts[1] = ProjectionMatrix * inpt[1].v.position;
    edgeVerts[2] = ProjectionMatrix * inpt[2].v.position;
    edgeVerts[3] = ProjectionMatrix * inpt[3].v.position;

    edgeVerts[0].xy /= edgeVerts[0].w;
    edgeVerts[1].xy /= edgeVerts[1].w;
    edgeVerts[2].xy /= edgeVerts[2].w;
    edgeVerts[3].xy /= edgeVerts[3].w;

    emit(0, n0, edgeVerts);
    emit(1, n0, edgeVerts);
    emit(3, n0, edgeVerts);
    emit(2, n0, edgeVerts);
#else
    emit(0, n0);
    emit(1, n0);
    emit(3, n0);
    emit(2, n0);
#endif
#endif // PRIM_QUAD

#ifdef PRIM_TRI
    vec3 A = (inpt[1].v.position - inpt[0].v.position).xyz;
    vec3 B = (inpt[2].v.position - inpt[0].v.position).xyz;
    vec3 n0 = normalize(cross(B, A));

#if defined(GEOMETRY_OUT_WIRE) || defined(GEOMETRY_OUT_LINE)
    vec4 edgeVerts[EDGE_VERTS];
    edgeVerts[0] = ProjectionMatrix * inpt[0].v.position;
    edgeVerts[1] = ProjectionMatrix * inpt[1].v.position;
    edgeVerts[2] = ProjectionMatrix * inpt[2].v.position;

    edgeVerts[0].xy /= edgeVerts[0].w;
    edgeVerts[1].xy /= edgeVerts[1].w;
    edgeVerts[2].xy /= edgeVerts[2].w;

    emit(0, n0, edgeVerts);
    emit(1, n0, edgeVerts);
    emit(2, n0, edgeVerts);
#else
    emit(0, n0);
    emit(1, n0);
    emit(2, n0);
#endif
#endif // PRIM_TRI

    EndPrimitive();
}

#endif

//--------------------------------------------------------------
// Fragment Shader
//--------------------------------------------------------------
#ifdef FRAGMENT_SHADER

in block {
    OutputVertex v;
    noperspective in vec4 edgeDistance;
    OSD_USER_VARYING_DECLARE
} inpt;

out vec4 outColor;

vec4
edgeColor(vec4 Cfill)
{
#if defined(GEOMETRY_OUT_WIRE) || defined(GEOMETRY_OUT_LINE)
#ifdef PRIM_TRI
    float d =
        min(inpt.edgeDistance[0], min(inpt.edgeDistance[1], inpt.edgeDistance[2]));
#endif
#ifdef PRIM_QUAD
    float d =
        min(min(inpt.edgeDistance[0], inpt.edgeDistance[1]),
            min(inpt.edgeDistance[2], inpt.edgeDistance[3]));
#endif
    vec4 Cedge = vec4(1.0, 1.0, 0.0, 1.0);
    float p = exp2(-2 * d * d);

#if defined(GEOMETRY_OUT_WIRE)
    if (p < 0.25) discard;
#endif

    Cfill.rgb = mix(Cfill.rgb, Cedge.rgb, p);
#endif
    return Cfill;
}

#if defined(PRIM_QUAD) || defined(PRIM_TRI)
void
main()
{
#ifdef GEOMETRY_UV_VIEW
    outColor = edgeColor(vec4(0.9));
    return;

#else
    vec3 N = (gl_FrontFacing ? inpt.v.normal : -inpt.v.normal);

    // generating a checkerboard pattern
    int checker = int(floor(20*inpt.color.r)+floor(20*inpt.color.g))&1;
    vec4 color = vec4(inpt.color.rg*checker, 1-checker, 1);

#if defined(GEOMETRY_OUT_WIRE) || defined(GEOMETRY_OUT_LINE)
    color = edgeColor(color);
#endif
    outColor = color;
#endif
}
#endif

#endif