PrepGeomShader()

void ShadingManager::PrepGeomShader ( )

private

Definition at line 489 of file ShadingManager.cpp.

{
    gsh->Clear();
 
    gsh->AddTopLine(GLSLLine("layout(triangles) in;", "Take 3 vertices of a triangles as input"));
    gsh->AddTopLine(GLSLLine("layout(triangle_strip, max_vertices = 3) out;"));
    gsh->AddTopLine(GLSLLine("", "The data passed in from the vertex shader"));
    gsh->AddTopLine(GLSLLine(R"(
in DATA
{
    float height;
    vec3 FragPos;
    vec3 Normal;
    vec2 TexCoord;
    vec4 Extras1;
} data_in[];
)"));
    gsh->AddTopLine(GLSLLine(""));
    gsh->AddTopLine(GLSLLine("out float height;", "Pass the height to the fragment shader"));
    gsh->AddTopLine(GLSLLine("out vec4 FragPos;", "Pass the position to the fragment shader"));
    gsh->AddTopLine(GLSLLine("out vec4 Extras1;", "Pass the extras to the fragment shader"));
    gsh->AddTopLine(GLSLLine("out vec3 Normal;", "Pass the normal to the fragment shader"));
    gsh->AddTopLine(GLSLLine("out vec2 TexCoord;", "Pass the texture coordinates to the fragment shader"));
    gsh->AddTopLine(GLSLLine("out mat3 TBN;", "Pass the Tangent Bitangent Normal matrix to the fragment shader"));
 
    gsh->AddUniform(GLSLUniform("_PV", "mat4"));
    gsh->AddUniform(GLSLUniform("_FlatShade", "float"));
    
    GLSLFunction main("main");
    main.AddLine(GLSLLine("vec3 a  = (_PV * gl_in[0].gl_Position).xyz;", "Vertex a of triangle"));
    main.AddLine(GLSLLine("vec3 b  = (_PV * gl_in[1].gl_Position).xyz;", "Vertex b of triangle"));
    main.AddLine(GLSLLine("vec3 c  = (_PV * gl_in[2].gl_Position).xyz;", "Vertex c of triangle"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("vec3 edge0 = b - c;"));
    main.AddLine(GLSLLine("vec3 edge1 = c - a;"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("vec2 deltaUV0 = data_in[1].TexCoord - data_in[0].TexCoord;"));
    main.AddLine(GLSLLine("vec2 deltaUV1 = data_in[2].TexCoord - data_in[0].TexCoord;"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("float invDet = 1.0f / (deltaUV0.x * deltaUV1.y - deltaUV1.x * deltaUV0.y);", "One over the determinant"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("vec3 tangent = vec3(invDet * (deltaUV1.y * edge0 - deltaUV0.y * edge1));"));
    main.AddLine(GLSLLine("vec3 bitangent = vec3(invDet * (-deltaUV1.x * edge0 + deltaUV0.x * edge1));"));
    main.AddLine(GLSLLine("mat4 model = mat4(1);", "A default model matrix"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("vec3 T = normalize(vec3(model * vec4(tangent, 0.0f)));"));
    main.AddLine(GLSLLine("vec3 B = normalize(vec3(model * vec4(bitangent, 0.0f)));"));
    main.AddLine(GLSLLine("vec3 N = normalize(vec3(model * vec4(cross(edge1, edge0), 0.0f)));"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("TBN = mat3(T, B, N);"));
    main.AddLine(GLSLLine(""));
    main.AddLine(GLSLLine("vec3 n = normalize(cross(edge1, edge0));", "Calculate face normal for flat shading"));
    main.AddLine(GLSLLine(""));
 
    for(int i=0;i<3;i++)
    {
        main.AddLine(GLSLLine("gl_Position = _PV * gl_in[" + std::to_string(i) + "].gl_Position;"));
        main.AddLine(GLSLLine("height = data_in[" + std::to_string(i) + "].height;"));
        main.AddLine(GLSLLine("TexCoord = data_in[" + std::to_string(i) + "].TexCoord;"));
        main.AddLine(GLSLLine("Extras1 = data_in[" + std::to_string(i) + "].Extras1;"));
        main.AddLine(GLSLLine("FragPos = vec4(data_in[" + std::to_string(i) + "].FragPos, 1.0f);"));
        main.AddLine(GLSLLine(R"(
        if(_FlatShade > 0.5f)
            Normal = n;
        else
            Normal = data_in[)" + std::to_string(i) + R"(].Normal;
        )"));
    main.AddLine(GLSLLine("EmitVertex();", "Emit the vertex"));
}
 
main.AddLine(GLSLLine("EndPrimitive();", "Emit the triangle"));
 
 
gsh->AddFunction(main);
 
}