BrimsonBhin
0703a5851b
Results are identical (tested with Olive 0.1.x). Using a straight multiply is faster if the compiler doesn't optimize pow(). It's also safer because with pow(), [the result is undefined if x<0 or if x=0 and y≤0](https://www.khronos.org/registry/OpenGL-Refpages/gl4/html/pow.xhtml).
97 lines
2.7 KiB
GLSL
97 lines
2.7 KiB
GLSL
#version 150
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uniform sampler2D tex_in;
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uniform int method_in;
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uniform float radius_in;
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uniform bool horiz_in;
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uniform bool vert_in;
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uniform bool repeat_edge_pixels_in;
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uniform vec2 ove_resolution;
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uniform int ove_iteration;
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in vec2 ove_texcoord;
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out vec4 fragColor;
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// Gaussian function uses PI
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#define M_PI 3.1415926535897932384626433832795
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// Methods
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#define METHOD_BOX_BLUR 0
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#define METHOD_GAUSSIAN_BLUR 1
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// Single gaussian formula (unused, mainly here for documentation/just in case)
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//float gaussian(float x, float sigma) {
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// return (1.0/(sigma*sqrt(2.0*M_PI)))*exp(-0.5*pow(x/sigma, 2.0));
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//}
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// Double gaussian formula, actually used in the code below
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// Should be faster than the single gaussian above since it doesn't need sqrt()
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float gaussian2(float x, float y, float sigma) {
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return (1.0/((sigma*sigma)*2.0*M_PI))*exp(-0.5*(((x*x) + (y*y))/(sigma*sigma)));
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}
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void main(void) {
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if (radius_in == 0.0
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|| (ove_iteration == 0 && !horiz_in)
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|| (ove_iteration == 1 && !vert_in)) {
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fragColor = texture(tex_in, ove_texcoord);
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return;
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}
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// We only sample on hard pixels, so we don't accept decimal radii
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float real_radius = ceil(radius_in);
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vec4 composite = vec4(0.0);
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float divider, sigma;
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if (method_in == METHOD_BOX_BLUR) {
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// Calculate the weight of each pixel based on the radius
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divider = 1.0 / real_radius;
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} else if (method_in == METHOD_GAUSSIAN_BLUR) {
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// Using (radius = 3 * sigma) because 3 standard deviations covers 97% of the blur according to this document:
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// http://chemaguerra.com/gaussian-filter-radius/
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sigma = real_radius;
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real_radius *= 3.0;
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// Use gaussian formula to calculate the weight of all pixels
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divider = 0.0;
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for (float i = -real_radius + 0.5; i <= real_radius; i += 2.0) {
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divider += gaussian2(i, 0.0, sigma);
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}
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}
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for (float i = -real_radius + 0.5; i <= real_radius; i += 2.0) {
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float weight;
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if (method_in == METHOD_BOX_BLUR) {
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weight = divider;
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} else if (method_in == METHOD_GAUSSIAN_BLUR) {
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weight = gaussian2(i, 0.0, sigma) / divider;
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}
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vec2 pixel_coord = ove_texcoord;
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if (ove_iteration == 0) {
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pixel_coord.x += i / ove_resolution.x;
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} else if (ove_iteration == 1) {
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pixel_coord.y += i / ove_resolution.y;
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}
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if (repeat_edge_pixels_in
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|| (pixel_coord.x >= 0.0
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&& pixel_coord.x < 1.0
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&& pixel_coord.y >= 0.0
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&& pixel_coord.y < 1.0)) {
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composite += texture(tex_in, pixel_coord) * weight;
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}
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}
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fragColor = composite;
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}
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