X-Git-Url: https://git.sesse.net/?p=movit;a=blobdiff_plain;f=blur_effect.cpp;h=90d1b68653b9af51c009c1fae48a7e007998da8d;hp=b48dc956e59dade84e49ac507de998dc4241f45d;hb=b09a4cb8dec09bcd1e42026d5b229b57e620e47c;hpb=322c03693ae23e5a5843dee9dcb74dfb3b7d43d8

diff --git a/blur_effect.cpp b/blur_effect.cpp
index b48dc95..90d1b68 100644
--- a/blur_effect.cpp
+++ b/blur_effect.cpp
@@ -114,12 +114,16 @@ void SingleBlurPassEffect::set_gl_state(GLuint glsl_program_num, const std::stri
 	} else {
 		float sum = 0.0f;
 		for (unsigned i = 0; i < NUM_TAPS + 1; ++i) {
-			float z = i / radius;
-
 			// Gaussian blur is a common, but maybe not the prettiest choice;
 			// it can feel a bit too blurry in the fine detail and too little
 			// long-tail. This is a simple logistic distribution, which has
 			// a narrower peak but longer tails.
+			//
+			// We interpret the radius as sigma, similar to Gaussian blur.
+			// Wikipedia says that sigma² = pi² s² / 3, which yields:
+			const float s = (sqrt(3.0) / M_PI) * radius;
+			float z = i / (2.0 * s);
+
 			weight[i] = 1.0f / (cosh(z) * cosh(z));
 
 			if (i == 0) {
@@ -158,13 +162,8 @@ void SingleBlurPassEffect::set_gl_state(GLuint glsl_program_num, const std::stri
 		float w2 = weight[base_pos + 1];
 
 		float offset, total_weight;
-		if (w1 + w2 < 1e-6) {
-			offset = 0.5f;
-			total_weight = 0.0f;
-		} else {
-			offset = w2 / (w1 + w2);
-			total_weight = w1 + w2;
-		}
+		combine_two_samples(w1, w2, &offset, &total_weight);
+
 		float x = 0.0f, y = 0.0f;
 
 		if (direction == HORIZONTAL) {