nuclear@13: uniform sampler2D tex;
nuclear@13: uniform float aspect, scale;
nuclear@13: uniform float lens_center_offset;
nuclear@13: uniform vec4 dist_factors;
nuclear@18: uniform vec2 tex_scale;
nuclear@13: 
nuclear@14: vec2 distort_texcoords(in vec2 tc);
nuclear@13: float barrel_scale(float x, in vec4 k);
nuclear@13: 
nuclear@13: void main()
nuclear@13: {
nuclear@14: 	vec2 tc = distort_texcoords(gl_TexCoord[0].xy);
nuclear@13: 
nuclear@18: 	float vis = any(greaterThan(tc, vec2(1.0))) || any(lessThan(tc, vec2(0.0))) ? 0.0 : 1.0;
nuclear@14: 
nuclear@18: 	gl_FragColor.rgb = texture2D(tex, tc * tex_scale).rgb * vis;
nuclear@13: 	gl_FragColor.a = 1.0;
nuclear@13: }
nuclear@13: 
nuclear@14: vec2 distort_texcoords(in vec2 tc)
nuclear@13: {
nuclear@13: 	// map tc [0, 1] -> [-1, 1]
nuclear@13: 	vec2 pt = tc * 2.0 - 1.0;
nuclear@13: 
nuclear@13: 	pt.x += lens_center_offset * 2.0;
nuclear@13: 	pt.y /= aspect;	// correct for aspect ratio
nuclear@13: 
nuclear@13: 	float rad = barrel_scale(dot(pt, pt), dist_factors);
nuclear@13: 	pt *= rad;	// scale the point by the computer distortion radius
nuclear@13: 
nuclear@14: 	pt /= scale;
nuclear@13: 	pt.y *= aspect;
nuclear@13: 	pt.x -= lens_center_offset * 2.0;
nuclear@13: 
nuclear@13: 	// map back to range [0, 1]
nuclear@13: 	return pt * 0.5 + 0.5;
nuclear@13: }
nuclear@13: 
nuclear@13: float barrel_scale(float rad, in vec4 k)
nuclear@13: {
nuclear@13: 	float radsq = rad * rad;
nuclear@13: 	float radquad = radsq * radsq;
nuclear@13: 	return k.x + k.y * radsq + k.z * radquad + k.w * radquad * radsq;
nuclear@13: }