varying vec2 t;
varying float z;

#vertex

void main() {
    vec4 v = gl_ModelViewMatrix * gl_Vertex;
    z = exp(1.25 * v.z);
//    z = 1.0 - (v.z + 1.7) * (1.0 / 1.7);
//    z = 1.0 - z;
    t = gl_MultiTexCoord0.xy;
    gl_Position = gl_ProjectionMatrix * v;
}

#fragment

uniform sampler2D tex;
uniform vec4 col[4];
uniform vec4 white;

void main() {
    vec4 ctl = texture2D(tex, t);
    vec4 c = ctl.x * mix(col[0], col[1], ctl.z)
           + ctl.y * mix(col[2], col[3], ctl.z);
    c += min(max(c.w, 0.0), 1.0) * white;
    gl_FragColor = c * z;
}