gradient.glsl
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vec3 grad(vec3 p, float d, sampler3D t)
{
vec3 px = vec3(p.x-d, p.y, p.z);
vec3 py = vec3(p.x, p.y-d, p.z);
vec3 pz = vec3(p.x, p.y, p.z-d);
float pVal = texture(t, p).g;
float dx = pVal - texture(t, px).r;
float dy = pVal - texture(t, py).r;
float dz = pVal - texture(t, pz).r;
return vec3(dx, dy, dz);
}
vec4 computeColor(vec3 p)
{
//compute the gradient
vec3 gradient = grad(p, 0.01, texIntensity);
vec4 color = vec4(0.0, 0.0, 0.0, 0.0);
float gradmag = length(gradient);
//compute the color based on the gradient
if(gradmag == 0.0)
return vec4(0.0, 0.0, 0.0, 0.0);
color.rgb = abs(normalize(gradient));
color.a = gradmag;
//compute lighting
vec3 lightDir = -normalize(diffuse0);
float light0 = dot(lightDir, gradient);
if(light0 < 0) light0 = 0;
lightDir = -normalize(diffuse1);
float light1 = dot(lightDir, gradient);
if(light1 < 0) light1 = 0;
float ambient = 0.5;
float lighting = light0 + light1 + ambient;
color.rgb = color.rgb*lighting;
return color;
}