47 lines
1.4 KiB
GLSL
47 lines
1.4 KiB
GLSL
#version 140
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in uvec4 position; // This will be the position of the vertex in model-space
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in uint normal;
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// The usual matrices are provided
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uniform mat4 cameraToClipMatrix;
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uniform mat4 worldToCameraMatrix;
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uniform mat4 modelToWorldMatrix;
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// This will be used by the fragment shader to calculate flat-shaded normals. This is an unconventional approach
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// but we use it in this example framework because not all surface extractor generate surface normals.
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out vec4 worldPosition;
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out vec4 worldNormal;
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// Returns +/- 1
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vec2 signNotZero(vec2 v)
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{
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return vec2((v.x >= 0.0) ? +1.0 : -1.0, (v.y >= 0.0) ? +1.0 : -1.0);
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}
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void main()
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{
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vec4 decodedPosition = position;
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decodedPosition.xyz = decodedPosition.xyz * (1.0 / 256.0);
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//Get the encoded bytes of the normal
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uint encodedX = (normal >> 8u) & 0xFFu;
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uint encodedY = (normal) & 0xFFu;
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// Map to range [-1.0, +1.0]
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vec2 e = vec2(encodedX, encodedY);
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e = e * vec2(1.0 / 127.5, 1.0 / 127.5);
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e = e - vec2(1.0, 1.0);
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// Now decode normal using listing 2 of http://jcgt.org/published/0003/02/01/
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vec3 v = vec3(e.xy, 1.0 - abs(e.x) - abs(e.y));
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if (v.z < 0) v.xy = (1.0 - abs(v.yx)) * signNotZero(v.xy);
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worldNormal.xyz = normalize(v);
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worldNormal.w = 1.0;
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// Standard sequence of OpenGL transformations.
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worldPosition = modelToWorldMatrix * decodedPosition;
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vec4 cameraPosition = worldToCameraMatrix * worldPosition;
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gl_Position = cameraToClipMatrix * cameraPosition;
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}
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