From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Wed, 10 Oct 2012 22:52:09 +0000 (+0200)
Subject: Drop the 8-way symmetry; it causes bugs due to normalized texture coordinates.
X-Git-Tag: 1.0~320
X-Git-Url: https://git.sesse.net/?p=movit;a=commitdiff_plain;h=71a27346652e54781215737255f757f6292ff120

Drop the 8-way symmetry; it causes bugs due to normalized texture coordinates.
---

diff --git a/deconvolution_sharpen_effect.cpp b/deconvolution_sharpen_effect.cpp
index d9d54aa..ab28eb3 100644
--- a/deconvolution_sharpen_effect.cpp
+++ b/deconvolution_sharpen_effect.cpp
@@ -372,8 +372,7 @@ void DeconvolutionSharpenEffect::update_deconvolution_kernel()
 	//   (G+H)     x0 + I x2     = y2
 	//
 	// This both increases accuracy and provides us with a very nice speed
-	// boost. We could have gone even further and went for 8-way symmetry
-	// like the shader does, but this is good enough right now.
+	// boost.
 	MatrixXf M(MatrixXf::Zero((R + 1) * (R + 1), (R + 1) * (R + 1)));
 	MatrixXf r_uv_flattened(MatrixXf::Zero((R + 1) * (R + 1), 1));
 	for (int outer_i = 0; outer_i < 2 * R + 1; ++outer_i) {
@@ -438,7 +437,6 @@ void DeconvolutionSharpenEffect::set_gl_state(GLuint glsl_program_num, const std
 		update_deconvolution_kernel();
 	}
 	// Now encode it as uniforms, and pass it on to the shader.
-	// (Actually the shader only uses about half of the elements.)
 	float samples[4 * (R + 1) * (R + 1)];
 	for (int y = 0; y <= R; ++y) {
 		for (int x = 0; x <= R; ++x) {
diff --git a/deconvolution_sharpen_effect.frag b/deconvolution_sharpen_effect.frag
index 62a8d6d..90ca3c1 100644
--- a/deconvolution_sharpen_effect.frag
+++ b/deconvolution_sharpen_effect.frag
@@ -3,19 +3,20 @@ uniform vec4 PREFIX(samples)[(R + 1) * (R + 1)];
 vec4 FUNCNAME(vec2 tc) {
 	// The full matrix has five different symmetry cases, that look like this:
 	//
-	// D * * C * * D
-	// * D * C * D *
-	// * * D C D * *
+	// D D D C D D D
+	// D D D C D D D
+	// D D D C D D D
 	// B B B A B B B
-	// * * D C D * *
-	// * D * C * D *
-	// D * * C * * D
+	// D D D C D D D
+	// D D D C D D D
+	// D D D C D D D
 	//
 	// We only store the lower-right part of the matrix:
 	//
-	// A B B 
-	// C D *
-	// C * D
+	// A B B B 
+	// C D D D
+	// C D D D
+	// C D D D
 
 	// Case A: Top-left sample has no symmetry.
 	vec4 sum = PREFIX(samples)[0].z * INPUT(tc);
@@ -32,28 +33,16 @@ vec4 FUNCNAME(vec2 tc) {
 		sum += sample.z * (INPUT(tc - sample.xy) + INPUT(tc + sample.xy));
 	}
 
-	// Case D: Diagonal samples have four-way symmetry.
-	for (int xy = 1; xy <= R; ++xy) {
-		vec4 sample = PREFIX(samples)[xy * (R + 1) + xy];
-		vec2 mirror_sample = vec2(sample.x, -sample.y);
-
-		vec4 local_sum = INPUT(tc - sample.xy) + INPUT(tc + sample.xy);
-		local_sum += INPUT(tc - mirror_sample.xy) + INPUT(tc + mirror_sample.xy);
-
-		sum += sample.z * local_sum;
-	}
-
-	// Case *: All other samples have eight-way symmetry.
+	// Case D: All other samples have four-way symmetry.
+	// (Actually we have eight-way, but since we are using normalized
+	// coordinates, we can't just flip x and y.)
 	for (int y = 1; y < R; ++y) {
-		for (int x = y + 1; x <= R; ++x) {
+		for (int x = 1; x <= R; ++x) {
 			vec4 sample = PREFIX(samples)[y * (R + 1) + x];
 			vec2 mirror_sample = vec2(sample.x, -sample.y);
 
 			vec4 local_sum = INPUT(tc - sample.xy) + INPUT(tc + sample.xy);
 			local_sum += INPUT(tc - mirror_sample.xy) + INPUT(tc + mirror_sample.xy);
-			local_sum += INPUT(tc - sample.yx) + INPUT(tc + sample.yx);
-			local_sum += INPUT(tc - mirror_sample.yx) + INPUT(tc + mirror_sample.yx);
-
 			sum += sample.z * local_sum;
 		}
 	}