Improve the ambient occlusion algorithm

Allow changing the depth ratio
Use correct winding for the triangle strip
Set pipeline texture wrapping to CLAMP_TO_EDGE

diff --git a/source/ambientocclusion.cpp b/source/ambientocclusion.cpp
index a3d8894cfe0d7a3735d37c0c44088ddf0a087670..2775e854cfe1d73b4b5c7f3786e8d440f91a8a66 100644 (file)
--- a/source/ambientocclusion.cpp
+++ b/source/ambientocclusion.cpp
@@ -31,19 +31,21 @@ const char occlude_fs[] =
        "void main()\n"
        "{\n"
        "       mat2 transform = mat2(texture2D(rotate, texcoord*screen_size/4.0)*2.0-1.0)\n"
-       "               *mat2(screen_size.y/screen_size.x, 0.0, 0.0, 1.0)*0.02;\n"
-       "       float depth_avg = 0.0;\n"
+       "               *mat2(screen_size.y/screen_size.x, 0.0, 0.0, 1.0)*3.0/screen_size.y;\n"
+       "       float sample = depth_ratio.x/(texture2D(depth, texcoord).r-depth_ratio.y);\n"
+       "       float sum = 0.0;\n"
        "       for(int i=0; i<=3; ++i)\n"
        "               for(int j=0; j<=3; ++j)\n"
        "               {\n"
        "                       vec2 offs = transform*vec2(float(i)-1.5, float(j)-1.5);\n"
-       "                       depth_avg += depth_ratio.x/(texture2D(depth, texcoord+offs).r-depth_ratio.y);\n"
+       "                       float dxy = length(offs)*-sample;\n"
+       "                       float dz = depth_ratio.x/(texture2D(depth, texcoord+offs).r-depth_ratio.y)-sample;\n"
+       "                       if(abs(dz)<3*dxy)\n"
+       "                               sum += atan(dz/dxy)/1.570796;\n"
+       "                       else if(dz<0)\n"
+       "                               sum -= 0.8;\n"
        "               }\n"
-       "       depth_avg /= 16;\n"
-       "       float sample = depth_ratio.x/(texture2D(depth, texcoord).r-depth_ratio.y);\n"
-       "       float diff = sample-depth_avg;\n"
-       "       float shade = min(diff*darkness, 0.0)+1.0;\n"
-       "       gl_FragColor = vec4(shade, 0.0, 0.0, 1.0);\n"
+       "       gl_FragColor = vec4(min(1.0-sum*darkness/16.0, 1.0), 0.0, 0.0, 1.0);\n"
        "}\n";
 
 const char combine_fs[] =
@@ -52,7 +54,6 @@ const char combine_fs[] =
        "uniform sampler2D occlusion;\n"
        "uniform vec2 screen_size;\n"
        "uniform vec2 depth_ratio;\n"
-       "uniform float edge_threshold;\n"
        "varying vec2 texcoord;\n"
        "void main()\n"
        "{\n"
@@ -63,8 +64,9 @@ const char combine_fs[] =
        "               for(int j=0; j<=3; ++j)\n"
        "               {\n"
        "                       vec2 offs = vec2(float(i)-1.5, float(j)-1.5)/screen_size;\n"
-       "                       float depth = depth_ratio.x/(texture2D(depth, texcoord+offs).r-depth_ratio.y);\n"
-       "                       if(abs(depth-sample)<edge_threshold)\n"
+       "                       float dxy = length(offs)*-sample;\n"
+       "                       float dz = depth_ratio.x/(texture2D(depth, texcoord+offs).r-depth_ratio.y)-sample;\n"
+       "                       if(abs(dz)<3*dxy)\n"
        "                       {\n"
        "                               sum += texture2D(occlusion, texcoord+offs).r;\n"
        "                               count += 1.0;\n"
@@ -108,34 +110,37 @@ AmbientOcclusion::AmbientOcclusion(unsigned w, unsigned h, float depth_ratio):
 
        occlude_texturing.attach(1, rotate_lookup);
 
-       depth_ratio = 1/depth_ratio;
-
        occlude_shdata.uniform(occlude_shader.get_uniform_location("depth"), 0);
        occlude_shdata.uniform(occlude_shader.get_uniform_location("rotate"), 1);
        occlude_shdata.uniform(occlude_shader.get_uniform_location("screen_size"), w, h);
-       occlude_shdata.uniform(occlude_shader.get_uniform_location("depth_ratio"), depth_ratio, 1+depth_ratio);
 
        combine_shdata.uniform(combine_shader.get_uniform_location("color"), 1);
        combine_shdata.uniform(combine_shader.get_uniform_location("depth"), 0);
        combine_shdata.uniform(combine_shader.get_uniform_location("occlusion"), 2);
        combine_shdata.uniform(combine_shader.get_uniform_location("screen_size"), w, h);
-       combine_shdata.uniform(combine_shader.get_uniform_location("depth_ratio"), depth_ratio, 1+depth_ratio);
-       combine_shdata.uniform(combine_shader.get_uniform_location("edge_threshold"), 0.05f);
 
-       set_darkness(15);
+       set_depth_ratio(depth_ratio);
+       set_darkness(1.5);
 
        MeshBuilder bld(quad);
        bld.begin(TRIANGLE_STRIP);
-       bld.vertex(-1, -1);
        bld.vertex(-1, 1);
-       bld.vertex(1, -1);
+       bld.vertex(-1, -1);
        bld.vertex(1, 1);
+       bld.vertex(1, -1);
        bld.end();
 }
 
-void AmbientOcclusion::set_darkness(float d)
+void AmbientOcclusion::set_depth_ratio(float depth_ratio)
+{
+       depth_ratio = 1/depth_ratio;
+
+       occlude_shdata.uniform(occlude_shader.get_uniform_location("depth_ratio"), depth_ratio, 1+depth_ratio);
+       combine_shdata.uniform(combine_shader.get_uniform_location("depth_ratio"), depth_ratio, 1+depth_ratio);
+}
+
+void AmbientOcclusion::set_darkness(float darkness)
 {
-       darkness = d;
        occlude_shdata.uniform(occlude_shader.get_uniform_location("darkness"), darkness);
 }
 

diff --git a/source/ambientocclusion.h b/source/ambientocclusion.h
index 1866baee4eb57aeeb95c2fd32206f8c0ff8602c5..4affd04987aef3f1b6ce6c5c71b99bf12a2a4b64 100644 (file)
--- a/source/ambientocclusion.h
+++ b/source/ambientocclusion.h
@@ -37,11 +37,11 @@ private:
        Program combine_shader;
        ProgramData combine_shdata;
        Mesh quad;
-       float darkness;
 
 public:
        AmbientOcclusion(unsigned, unsigned, float);
 
+       void set_depth_ratio(float);
        void set_darkness(float);
 
        virtual void render(const Texture2D &, const Texture2D &);

diff --git a/source/pipeline.cpp b/source/pipeline.cpp
index 63bdc4e84bbf82f10b883ade20f7d89c6216bc12..5294ffbd859d84f4c29ce7878dcd5a01a6fd376b 100644 (file)
--- a/source/pipeline.cpp
+++ b/source/pipeline.cpp
@@ -120,12 +120,14 @@ void Pipeline::add_postprocessor(PostProcessor &pp)
                color_buf = new Texture2D;
                color_buf->set_min_filter(NEAREST);
                color_buf->set_mag_filter(NEAREST);
+               color_buf->set_wrap(CLAMP_TO_EDGE);
                color_buf->storage((hdr ? RGB16F : RGB), width, height);
                fbo->attach(COLOR_ATTACHMENT0, *color_buf, 0);
 
                depth_buf = new Texture2D;
                depth_buf->set_min_filter(NEAREST);
                depth_buf->set_mag_filter(NEAREST);
+               depth_buf->set_wrap(CLAMP_TO_EDGE);
                depth_buf->storage(DEPTH_COMPONENT, width, height);
                fbo->attach(DEPTH_ATTACHMENT, *depth_buf, 0);
        }