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48 lines
2.3 KiB
GLSL
48 lines
2.3 KiB
GLSL
// draws the geometry into the six faces of a cube shadow map at once, one invocation per face. the input is in the space of the
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// map, with the lamp at the origin. the faces go in the order of the faces of a cube map (+x, -x, +y, -y, +z, -z), each looks the
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// way glm::lookAt() with the usual up vectors of cube maps sets it, with a 90 degree projection of infinite reach and reversed
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// depth like the one of the scene: the depth is near / d, d the distance along the axis of the face
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layout(triangles, invocations = 6) in;
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layout(triangle_strip, max_vertices = 3) out;
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in vec3 g_pos[];
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in vec2 g_coord[];
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out vec2 f_coord;
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// near plane of the map, metres: closer surfaces (the lamp itself) cast no shadows
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layout(location = 0) uniform float cube_near;
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// layer of the cube map array the first face of the map is in
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layout(location = 1) uniform int cube_layer;
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// right, up and forward axes of the faces
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const vec3 face_right[6] = vec3[](vec3(0.0, 0.0, -1.0), vec3(0.0, 0.0, 1.0), vec3(1.0, 0.0, 0.0), vec3(1.0, 0.0, 0.0), vec3(1.0, 0.0, 0.0), vec3(-1.0, 0.0, 0.0));
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const vec3 face_up[6] = vec3[](vec3(0.0, -1.0, 0.0), vec3(0.0, -1.0, 0.0), vec3(0.0, 0.0, 1.0), vec3(0.0, 0.0, -1.0), vec3(0.0, -1.0, 0.0), vec3(0.0, -1.0, 0.0));
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const vec3 face_forward[6] = vec3[](vec3(1.0, 0.0, 0.0), vec3(-1.0, 0.0, 0.0), vec3(0.0, 1.0, 0.0), vec3(0.0, -1.0, 0.0), vec3(0.0, 0.0, 1.0), vec3(0.0, 0.0, -1.0));
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void main()
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{
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int face = gl_InvocationID;
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vec4 clip[3];
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for (int i = 0; i < 3; i++)
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clip[i] = vec4(dot(g_pos[i], face_right[face]), dot(g_pos[i], face_up[face]), cube_near, dot(g_pos[i], face_forward[face]));
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// triangles wholly outside of the face are not sent further
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if ((clip[0].w < cube_near) && (clip[1].w < cube_near) && (clip[2].w < cube_near))
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return;
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if ((clip[0].x > clip[0].w) && (clip[1].x > clip[1].w) && (clip[2].x > clip[2].w))
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return;
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if ((clip[0].x < -clip[0].w) && (clip[1].x < -clip[1].w) && (clip[2].x < -clip[2].w))
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return;
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if ((clip[0].y > clip[0].w) && (clip[1].y > clip[1].w) && (clip[2].y > clip[2].w))
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return;
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if ((clip[0].y < -clip[0].w) && (clip[1].y < -clip[1].w) && (clip[2].y < -clip[2].w))
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return;
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for (int i = 0; i < 3; i++)
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{
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gl_Layer = cube_layer + face;
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gl_Position = clip[i];
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f_coord = g_coord[i];
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EmitVertex();
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}
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EndPrimitive();
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}
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