uniform sampler3D tex, texIndex;
uniform int depth;

varying float sphIndex;

void main()
{
    vec3 coord3, coord3Index;
    vec4 lastColor, currColor, color;
    color = vec4(0, 0, 0, 0);

    float currIndex = 0.0;
    float lastIndex = 0.0;
    float deltaIndex = 0.0;

    coord3.xy = gl_TexCoord[0].st;
    coord3Index.xy = coord3.xy;

    float zIndex;

    color = vec4(0.0, 0.0, 1.0, 1.0);

    for(int i = 0; i < depth; i++) {
        zIndex = (i*1.0)/(depth*1.0);
        coord3Index.z = zIndex;
        vec4 vCurrIndex = texture3D(texIndex, coord3Index);
        currIndex = vCurrIndex.r;


        if ( sphIndex <= currIndex) {¨
            if ( currIndex < 0.5) {
                color = vec4(0.0, 0.0, 1.0, 1.0);
            } else color = vec4(0.0, currIndex, 0.0, 1.0);

            if ( sphIndex < 0.5) {
                color = color + vec4(sphIndex, 0.0, 0.0, 1.0);
            }
            i = depth +1;

        } else {
            lastIndex = currIndex;
        }
    }


    gl_FragColor = color;
}