From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 15 Jun 2019 12:18:09 +0000 (+0300)
Subject: Improve ambient occlusion edge detection
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=7e67337718b38e23a24172806b23c744f5dc58fe;hp=44b8b5f558dc07eab052994867e5247b73618253

Improve ambient occlusion edge detection

The depth thresholds are now based on the distance of the sample from the
center, which works better in the presence of sloped flat surfaces.
---

diff --git a/shaderlib/ambientocclusion_combine.glsl b/shaderlib/ambientocclusion_combine.glsl
index 1e8bd821..05aea60a 100644
--- a/shaderlib/ambientocclusion_combine.glsl
+++ b/shaderlib/ambientocclusion_combine.glsl
@@ -5,17 +5,19 @@ import ambientocclusion;
 void main()
 {
 	vec3 center = unproject(vec3(vertex.xy, texture(depth, texcoord).r));
-	float min_depth = project(vec3(center.xy, center.z+occlusion_radius*0.1)).z;
-	float max_depth = project(vec3(center.xy, center.z-occlusion_radius*0.1)).z;
 	vec2 tex_scale = 1.0/vec2(textureSize(occlusion, 0));
 	float sum = 0.0;
 	float count = 0.0;
 	for(int i=0; i<4; ++i)
 		for(int j=0; j<4; ++j)
 		{
-			vec2 offset = vec2(float(i)-1.5, float(j)-1.5)*tex_scale;
-			float occ = texture(occlusion, texcoord+offset).r;
-			float sample = texture(depth, texcoord+offset).r;
+			vec2 offset = vec2(float(i), float(j))-1.5;
+			vec2 sample_coord = texcoord+offset*tex_scale;
+			float occ = texture(occlusion, sample_coord).r;
+			float sample = texture(depth, sample_coord).r;
+			float z_range = occlusion_radius*length(offset)*0.1;
+			float min_depth = project(vec3(center.xy, center.z+z_range)).z;
+			float max_depth = project(vec3(center.xy, center.z-z_range)).z;
 			if(sample>=min_depth && sample<=max_depth)
 			{
 				sum += occ;