#vertex

void main() {
    gl_Position = ftransform();
}

#fragment

uniform sampler2D cld;
uniform sampler2D pat;
uniform vec4 cp[3];

void main() {
    int i;
    float c = 0.0;
    for (i = 0;  i < 3;  ++i)
        c += texture2D(cld, cp[i].z * gl_FragCoord.xy + cp[i].xy).r * cp[i].w;
    gl_FragColor = vec4(0.7, 0.7, 0.7, 0.0) + c * vec4(0.8, 0.7, 0.5, 0.0)
                 - vec4(0.1, 0.1, 0.1, 0.0) * (1.0 - texture2D(pat, 0.125 * gl_FragCoord.xy).r);
}