33 lines
851 B
GLSL
33 lines
851 B
GLSL
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#version 330 core
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// corners of a full-screen triangle at the far plane in normalized device coordinates
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const vec4 positions[3] = vec4[3](
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vec4(-1.0, -1.0, 1.0, 1.0),
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vec4( 3.0, -1.0, 1.0, 1.0),
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vec4(-1.0, 3.0, 1.0, 1.0)
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);
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// uniform variables, same for all vertices
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uniform mat4 projection;
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uniform mat4 modelView;
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// vertex shader outputs
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out vec3 viewDirection;
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void main()
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{
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// compute necessary inverse matrices
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mat4 inverseProjection = inverse(projection);
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mat3 inverseNormalMatrix = transpose(mat3(modelView));
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// look up normalized device coordinates from constant using vertex index
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vec4 ndc = positions[gl_VertexID];
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// unproject NDC coordinates to compute a direction
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vec3 unprojected = (inverseProjection * ndc).xyz;
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viewDirection = inverseNormalMatrix * unprojected;
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// projection copied as is
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gl_Position = ndc;
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}
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