webgcode

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#extension GL_EXT_frag_depth : require
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varying vec3 AABB_min;
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varying vec3 AABB_max;
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varying vec3 positionK;
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/*INCLUDE_FRAGLIB*/
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void main() {
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    vec2 pos = positionK.xy;
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//lets destroy the fragments that are really out there between the input corner and the dilated corner
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    if(any(bvec4(lessThan(pos, AABB_min.xy), greaterThan(pos, AABB_max.xy))))
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        discard;
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// ok, we were pessimistic, but one thing still holds:
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// the true Z value can never ever be higher or lower than any Z value of the input vertices,
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// so we clip to get back to some reality
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    float z = clamp(positionK.z, AABB_min.z, AABB_max.z);
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// go back to fragment world
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    z =  (0.5 * z + 0.5);
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// update the depth buffer, since what was a nice triangle is now a triangle with 2 bent corners (flattened by the Z clamp).
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    gl_FragDepthEXT = z;
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    gl_FragData[0] = vec4(1.0 - z, 0.0, 0.0, 1.0);
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}