Changeset 3320 for GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/ssao.cg

Timestamp:

02/19/09 12:05:56 (16 years ago)

Author:

mattausch

Message:

 

File:

• GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/ssao.cg (modified) (4 diffs)

GTP/trunk/App/Demos/Vis/FriendlyCulling/src/shaders/ssao.cg

@@ -156 +156 @@
 
 
-/** The ssao shader returning the an intensity value between 0 and 1
-        This version of the ssao shader uses the dotproduct between pixel and 
-        sample normal as weight.
+/** The ssao shader returning the an intensity value between 0 and 1.
+        This version of the ssao shader uses the dotproduct between 
+        pixel-to-sample direction and sample normal as weight.
+
+    The algorithm works like the following:
+        1) Check in a circular area around the current position.
+        2) Shoot vectors to the positions there, and check the angle to these positions.
+        3) Summing up these angles gives an estimation of the occlusion at the current position.
 */
 float3 ssao2(fragment IN,
@@ -172 +177 @@
                          float3 tr, 
                          float3 viewDir,
-                         sampler2D normalTex,
-                         float sampleIntensity
+                         float convergence,
+                         float sampleIntensity,
+                         bool isMovingObject,
+                         sampler2D normalTex
                          )
 {
         float total_ao = .0f;
+        float validSamples = .0f;
         float numSamples = .0f;
-        float validSamples = .0f;
 
         for (int i = 0; i < NUM_SAMPLES; ++ i) 
         {
-                const float2 offset = samples[i];
-
-#if 1
+                float2 offset;
+
                 ////////////////////
-                //-- add random noise: reflect around random normal vector (rather slow!)
-
-                const float2 mynoise = tex2Dlod(noiseTex, float4(IN.texCoord * 4.0f, 0, 0)).xy;
-                const float2 offsetTransformed = myreflect(offset, mynoise);
-#else
-                const float2 offsetTransformed = offset;
-#endif
+                //-- add random noise: reflect around random normal vector 
+                //-- (affects performance for some reason!)
+
+                if (convergence < SSAO_CONVERGENCE_THRESHOLD)
+                {
+                        float2 mynoise = tex2Dlod(noiseTex, float4(IN.texCoord * 4.0f, 0, 0)).xy;
+                        //offset = myreflect(samples[i], mynoise);
+                        offset = myrotate(samples[i], mynoise.x);
+                }
+                else
+                {
+                        offset = samples[i];
+                }
+                
                 // weight with projected coordinate to reach similar kernel size for near and far
-                //const float2 texcoord = IN.texCoord.xy + offsetTransformed * scaleFactor + jitter;
-                const float2 texcoord = IN.texCoord.xy + offsetTransformed * scaleFactor;
-
-                //if ((texcoord.x <= 1.0f) && (texcoord.x >= 0.0f) && (texcoord.y <= 1.0f) && (texcoord.y >= 0.0f)) ++ numSamples;
-                float4 sampleColor = tex2Dlod(colors, float4(texcoord, 0, 0));
-
+                const float2 texcoord = IN.texCoord.xy + offset * scaleFactor;
+
+                const float4 sampleColor = tex2Dlod(colors, float4(texcoord, .0f, .0f));
                 const float3 samplePos = ReconstructSamplePos(sampleColor.w, texcoord, bl, br, tl, tr);
+                
+
+                ////////////////
+                //-- compute contribution of sample using the direction and angle
+
+                float3 dirSample = samplePos - centerPosition;
+
+                //const float minDist = 9e-1f;
+                const float minDist = 1e-2f;
+
+                //const float sqrLen = max(SqrLen(dirSample), minDist);
+                //const float lengthToSample = sqrt(sqrLen);
+                const float lengthToSample =  max(length(dirSample), minDist);
+
+                dirSample /= lengthToSample; // normalize
+
+                // angle between current normal and direction to sample controls AO intensity.
+                float cosAngle = dot(dirSample, normal);
+
                 // the normal of the current sample
                 const float3 sampleNormal = tex2Dlod(normalTex, float4(texcoord, 0, 0)).xyz;
 
-
-                ////////////////
-                //-- compute contribution of sample using the direction and angle
-
-                float3 dirSample = samplePos - centerPosition;
-
-                const float sqrLen = max(SqrLen(dirSample), 1e-2f);
-                const float lengthToSample = sqrt(sqrLen);
-                //const float lengthToSample = max(length(dirSample), 1e-6f);
-
-                dirSample /= lengthToSample; // normalize
-
                 // angle between current normal and direction to sample controls AO intensity.
-                float cosAngle = .5f + dot(sampleNormal, -normal) * 0.5f;
-                // use binary decision to cull samples that are behind current shading point
-                cosAngle *= step(0.0f, dot(dirSample, normal));
-        
-                const float aoContrib = sampleIntensity / sqrLen;
+                float cosAngle2 = .5f + dot(sampleNormal, -normal) * 0.5f;
+                
+                //const float aoContrib = sampleIntensity / sqrLen;
+                const float aoContrib = sampleIntensity / lengthToSample;
+
                 //const float aoContrib = (1.0f > lengthToSample) ? occlusionPower(9e-2f, DISTANCE_SCALE + lengthToSample): .0f;
-
-                total_ao += cosAngle * aoContrib;
+                total_ao += max(cosAngle, .0f) * aoContrib * cosAngle2;
+
+                ++ numSamples;
 
                 // check if the samples have been valid in the last frame
-                validSamples += (1.0f - step(1.0f, lengthToSample)) * sampleColor.x;
-
-                ++ numSamples;
-        }
-
+                // only mark sample as invalid if in the last / current frame
+                // they possibly have any influence on the ao
+
+                const float changeFactor = sampleColor.y;
+                const float pixelValid = sampleColor.x;
+
+                // hack:
+                // we check if the sample could have been near enough 
+                // to the current pixel or if the angle is small enough
+                // to have any influence in the current or last frame
+#if 1
+                const float tooFarAway = step(0.5f, lengthToSample - changeFactor);
+                if (pixelValid < 2.0f)
+                        validSamples = max(validSamples, pixelValid * (1.0f - tooFarAway) * step(-0.1f, cosAngle));
+                else
+                        validSamples = max(validSamples, pixelValid);
+#else
+                validSamples = max(validSamples, pixelValid);
+#endif
+
+#ifdef USE_GTX
+                // we can bail out early and use a minimal #samples)
+                // if some conditions are met as long as the hardware supports it
+                if (numSamples >= MIN_SAMPLES)
+                {
+                        //break;
+                        // if the pixel belongs to a static object and all the samples stay valid in the current frame
+                        if (!isMovingObject && (validSamples < 1.0f) && (convergence > NUM_SAMPLES)) break;
+                        // if the pixel belongs to a dynamic object but the #accumulated samples for this pixel is sufficiently high 
+                        // (=> there was no discontinuity recently)
+                        //else if (isMovingObject && (convergence > SSAO_CONVERGENCE_THRESHOLD)) break;
+                        //else if (isMovingObject && (convergence > NUM_SAMPLES * 5)) break;
+                }
+#endif
+        }
+
+        // "normalize" ao contribution
         total_ao /= numSamples;
 
@@ -238 +288 @@
         // => compensate for this (on the other hand, projected sampling area could be larger!)
         const float viewCorrection = 1.0f + VIEW_CORRECTION_SCALE * max(dot(viewDir, normal), 0.0f);
-        total_ao += cosAngle * aoContrib * viewCorrection;
-
+        total_ao *= viewCorrection;
 #endif
 
-        return float3(max(0.0f, 1.0f - total_ao), validSamples, numSamples);
+        //return float3(total_ao, validSamples, numSamples);
+        return float3(min(1.0f, total_ao), validSamples, numSamples);
 }
 
@@ -450 +500 @@
         if (eyeSpaceDepth < DEPTH_THRESHOLD)
         {
-                ao = ssao(IN, colors, noiseTex, samples, normal, eyeSpacePos.xyz, scaleFactor, bl, br, tl, tr, normalize(viewDir), oldWeight, sampleIntensity, isMovingObject);
+                //ao = ssao(IN, colors, noiseTex, samples, normal, eyeSpacePos.xyz, scaleFactor, bl, br, tl, tr, normalize(viewDir), oldWeight, sampleIntensity, isMovingObject);
+                ao = ssao2(IN, colors, noiseTex, samples, normal, eyeSpacePos.xyz, scaleFactor, bl, br, tl, tr, normalize(viewDir), oldWeight, sampleIntensity, isMovingObject, normals);
                 //ao = ssao2(IN, colors, noiseTex, samples, normal, eyeSpacePos.xyz, scaleFactor, bl, br, tl, tr, normalize(viewDir), normals, sampleIntensity);
         }