111 lines
3.0 KiB
GLSL
111 lines
3.0 KiB
GLSL
uniform sampler2D tex_in;
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uniform vec4 color_in;
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uniform float distance_in;
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uniform float angle_in;
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uniform float radius_in;
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uniform float opacity_in;
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uniform vec2 resolution_in;
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uniform sampler2D previous_iteration_in;
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uniform bool fast_in;
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uniform int ove_iteration;
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in vec2 ove_texcoord;
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out vec4 frag_color;
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// Gaussian function uses PI
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#define M_PI 3.1415926535897932384626433832795
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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 (ove_iteration == 2 || radius_in == 0.0) {
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// Merge step
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vec4 composite = texture(tex_in, ove_texcoord);
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if (composite.a < 1.0) {
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// Convert degrees to radians
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float shadow_angle = ((angle_in + 90.0)*M_PI)/180.0;
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vec2 shadow_offset = vec2(cos(shadow_angle) * distance_in, sin(shadow_angle) * distance_in);
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shadow_offset /= resolution_in;
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shadow_offset += ove_texcoord;
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vec4 shadow_color = texture(previous_iteration_in, shadow_offset);
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shadow_color.rgb = color_in.rgb * shadow_color.a;
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shadow_color *= 1.0 - composite.a;
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shadow_color *= opacity_in;
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composite += shadow_color;
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}
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frag_color = composite;
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} else {
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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 (fast_in) {
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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 {
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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 (fast_in) {
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weight = divider;
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} else {
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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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vec4 tex_col;
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if (ove_iteration == 0) {
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pixel_coord.x += i / resolution_in.x;
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// Pull from main texture
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tex_col = texture(tex_in, pixel_coord);
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} else if (ove_iteration == 1) {
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pixel_coord.y += i / resolution_in.y;
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// Pull from previous iteration
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tex_col = texture(previous_iteration_in, pixel_coord);
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}
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composite += tex_col * weight;
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}
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frag_color = composite;
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}
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}
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