gistfile1.txt

#version 110

void main(void) {
    gl_Position     = ftransform();
    gl_FrontColor   = gl_Color;
    gl_TexCoord[0]  = gl_MultiTexCoord0;
}

%% -- FRAG

#version 110

uniform sampler2D tex;
uniform sampler2D depth;
uniform float start;
uniform float end;

uniform vec4 fog_color;

void main(void) {
    vec2 pos = vec2(gl_TexCoord[0]);

    float z = 1.0/texture2D(depth, pos).x;


    float f = (end - z)/(end-start);

    vec4 color;
    color = texture2D(tex,pos);
    color *= f;
    color += (1.0-f)*fog_color;
    gl_FragColor = color;


//  gl_FragColor = vec4(z);
//  gl_FragColor = 0.5*texture2D(tex, pos);
}