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// Fragment shader for 2D texture with shadow attenuation
// Brian Paul
uniform sampler2D tex2d;
uniform vec3 lightPos;
void main()
{
// XXX should compute this from lightPos
vec2 shadowCenter = vec2(-0.25, -0.25);
// d = distance from center
float d = distance(gl_TexCoord[0].xy, shadowCenter);
// attenuate and clamp
d = clamp(d * d * d, 0.0, 2.0);
// modulate texture by d for shadow effect
gl_FragColor = d * texture2D(tex2d, gl_TexCoord[0].xy, 0.0);
}
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