25 lines
815 B
GLSL
25 lines
815 B
GLSL
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// Pass to fragment shader with the same name
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varying vec2 TexCoords;
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void main(void)
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{
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gl_Position = gl_Vertex;
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// The origin of the texture coordinates locates at bottom-left
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// corner rather than top-left corner as defined on screen quad.
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// Instead of using texture coordinates passed in by OpenGL, we
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// calculate TexCoords based on vertex position as follows.
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//
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// Vertex[0] (-1, -1) to (0, 0)
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// Vertex[1] (-1, 1) to (0, 1)
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// Vertex[2] ( 1, 1) to (1, 1)
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// Vertex[3] ( 1, -1) to (1, 0)
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//
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// Texture coordinate system in OpenGL operates differently from
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// DirectX 3D. It is not necessary to offset TexCoords to texel
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// center by adding 1.0 / TextureSize / 2.0
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TexCoords = (gl_Vertex.xy * 0.5 + 0.5);
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}
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