Merge pull request #3804 from supertuxkart/feature/raytracer-reflexion

Enable Space Screen Raytracer for real time reflections

data/shaders/IBL.frag

@@ -1,5 +1,6 @@
 uniform sampler2D ntex;
 uniform sampler2D dtex;
+uniform sampler2D albedo;
 
 #ifdef GL_ES
 layout (location = 0) out vec4 Diff;
@@ -14,6 +15,91 @@ out vec4 Spec;
 #stk_include "utils/DiffuseIBL.frag"
 #stk_include "utils/SpecularIBL.frag"
 
+
+vec3 getXcYcZc(int x, int y, float zC)
+{
+    // We use perspective symetric projection matrix hence P(0,2) = P(1, 2) = 0
+    float xC= (2. * (float(x)) / u_screen.x - 1.) * zC / u_projection_matrix[0][0];
+    float yC= (2. * (float(y)) / u_screen.y - 1.) * zC / u_projection_matrix[1][1];
+    return vec3(xC, yC, zC);
+}
+
+float makeLinear(float f, float n, float z)
+{
+    return (2 * n) / (f + n - z * (f - n));
+}
+
+vec3 CalcViewPositionFromDepth(in vec2 TexCoord, in sampler2D DepthMap)
+{
+    // Combine UV & depth into XY & Z (NDC)
+    float z = makeLinear(1000.0, 1.0, textureLod(DepthMap, TexCoord, 0.).x);
+    vec3 rawPosition                = vec3(TexCoord, z);
+
+    // Convert from (0, 1) range to (-1, 1)
+    vec4 ScreenSpacePosition        = vec4( rawPosition * 2 - 1, 1);
+
+    // Undo Perspective transformation to bring into view space
+    vec4 ViewPosition               = u_inverse_projection_matrix * ScreenSpacePosition;
+
+    // Perform perspective divide and return
+    return                          ViewPosition.xyz / ViewPosition.w;
+}
+
+float GetVignette(float factor)
+{
+    vec2 inside = (gl_FragCoord.xy / u_screen) - 0.5;
+    float vignette = 1. - dot(inside, inside) * 5;
+    return clamp(pow(vignette, factor), 0., 1.0);
+}
+
+vec3 RayCast(vec3 dir, inout vec3 hitCoord, out float dDepth, in sampler2D DepthMap, in vec3 fallback, float spread)
+{
+    dir *= 0.25f;
+
+    for(int i = 0; i < 8; ++i) {
+        hitCoord               += dir;
+
+        vec4 projectedCoord     = u_projection_matrix * vec4(hitCoord, 1.0);
+        projectedCoord.xy      /= projectedCoord.w;
+        projectedCoord.xy       = projectedCoord.xy * 0.5 + 0.5;
+
+        float depth             = CalcViewPositionFromDepth(projectedCoord.xy, DepthMap).z;
+        dDepth                  = hitCoord.z - depth;
+
+        if(dDepth < 0.0)
+        {
+            // Texture wrapping to extand artifcially the range of the lookup texture
+            // FIXME can be improved to lessen the distortion
+            projectedCoord.y = min(.99, projectedCoord.y);
+            projectedCoord.x = min(.99, projectedCoord.x);
+            projectedCoord.x = max(.01, projectedCoord.x);
+
+            // We want only reflection on nearly horizontal surfaces
+            float cutout = dot(dir, vec3(0., 0., -1.));
+
+            if ((projectedCoord.x > 0.0 && projectedCoord.x < 1.0) 
+                && (projectedCoord.y > 0.0 && projectedCoord.y < 1.0) 
+                && (cutout > 10)
+               )
+            {
+                // FIXME We need to generate mipmap to take into account the gloss map
+                vec3 finalColor = textureLod(albedo, projectedCoord.xy, spread).rgb;
+                //return finalColor;
+                return mix(fallback, finalColor, GetVignette(4.));
+
+            }
+            else
+            {
+                return fallback;
+            }
+        }
+    }
+
+    return fallback;
+}
+
+// Main ===================================================================
+
 void main(void)
 {
     vec2 uv = gl_FragCoord.xy / u_screen;
@@ -25,7 +111,39 @@ void main(void)
 
     vec4 xpos = getPosFromUVDepth(vec3(uv, z), u_inverse_projection_matrix);
     vec3 eyedir = -normalize(xpos.xyz);
+    // Extract roughness
     float specval = texture(ntex, uv).z;
 
+#ifdef GL_ES
     Spec = vec4(.25 * SpecularIBL(normal, eyedir, specval), 1.);
+#else
+    // :::::::: Compute Space Screen Reflection ::::::::::::::::::::::::::::::::::::
+
+    float lineardepth = textureLod(dtex, uv, 0.).x;
+
+    // Fallback (if the ray can't find an intersection we display the sky)
+    vec3 fallback = .25 * SpecularIBL(normal, eyedir, specval);
+
+    float View_Depth            = makeLinear(1000.0, 1.0, lineardepth);
+    vec3 ScreenPos              = xpos.xyz;
+    vec4 View_Pos               = u_inverse_projection_matrix * vec4(ScreenPos, 1.0f);
+         View_Pos              /= View_Pos.w;
+
+    // Reflection vector
+    vec3 reflected              = normalize(reflect(eyedir, normal));
+
+    // Ray cast
+    vec3 hitPos                 = View_Pos.xyz;
+    float dDepth;
+    float minRayStep            = 100.0f;
+
+    vec3 outColor = RayCast(reflected * max(minRayStep, -xpos.z),
+                            hitPos, dDepth, dtex, fallback, 0.0);
+    
+    // TODO temporary measure the lack of mipmaping for RTT albedo
+    // Implement it in proper way
+    outColor = mix(fallback, outColor, specval);
+    Spec = vec4(outColor.rgb, 1.0);
+#endif
+
 }

data/shaders/combine_diffuse_color.frag

@@ -21,6 +21,7 @@ void main()
     // Metallic map is stored in normal color framebuffer .w
     // Emit map is stored in diffuse color framebuffer.w
     float metallicMapValue = texture(normal_color, tc).w;
+    float specMapValue = texture(normal_color, tc).z;
     float emitMapValue = diffuseMatColor.w;
 
     float ao = texture(ssao_tex, tc).x;
@@ -28,7 +29,12 @@ void main()
     vec3 SpecularComponent = texture(specular_map, tc).xyz;
 
     vec3 diffuse_color_for_mix = diffuseMatColor.xyz * 4.0;
+
+    // FIXME enable this once the fallback shader is properly done!!!
+    //vec3 metallicMatColor = mix(vec3(specMapValue), diffuse_color_for_mix, metallicMapValue);
     vec3 metallicMatColor = mix(vec3(0.04), diffuse_color_for_mix, metallicMapValue);
+    // END FIXME
+    
     vec3 tmp = DiffuseComponent * mix(diffuseMatColor.xyz, vec3(0.0), metallicMapValue) + (metallicMatColor * SpecularComponent);
 
     vec3 emitCol = diffuseMatColor.xyz + (diffuseMatColor.xyz * diffuseMatColor.xyz * emitMapValue * emitMapValue * 10.0);

data/shaders/degraded_ibl.frag

@@ -19,5 +19,5 @@ void main(void)
     vec3 normal = normalize(DecodeNormal(2. * texture(ntex, uv).xy - 1.));
 
     Diff = vec4(0.25 * DiffuseIBL(normal), 1.);
-    Spec = vec4(0., 0., 0., 1.);
+    Spec = vec4(0.031, 0.106, 0.173, 1.);
 }

src/graphics/lighting_passes.cpp

@@ -168,7 +168,7 @@ public:
 };
 
 // ============================================================================
-class IBLShader : public TextureShader<IBLShader, 3>
+class IBLShader : public TextureShader<IBLShader, 4>
 {
 public:
     IBLShader()
@@ -178,7 +178,8 @@ public:
         assignUniforms();
         assignSamplerNames(0, "ntex",  ST_NEAREST_FILTERED,
                            1, "dtex",  ST_NEAREST_FILTERED,
-                           2, "probe", ST_TRILINEAR_CUBEMAP);
+                           2, "probe", ST_TRILINEAR_CUBEMAP,
+                           3, "albedo",ST_NEAREST_FILTERED);
     }   // IBLShader
 };   // IBLShader
 
@@ -293,7 +294,8 @@ static void renderPointLights(unsigned count,
 // ----------------------------------------------------------------------------
 void LightingPasses::renderEnvMap(GLuint normal_depth_texture,
                                   GLuint depth_stencil_texture,
-                                  GLuint specular_probe)
+                                  GLuint specular_probe,
+                                  GLuint albedo_buffer)
 {
     glDisable(GL_DEPTH_TEST);
     glEnable(GL_BLEND);
@@ -317,7 +319,8 @@ void LightingPasses::renderEnvMap(GLuint normal_depth_texture,
         IBLShader::getInstance()->setTextureUnits(
             normal_depth_texture,
             depth_stencil_texture,
-            specular_probe);
+            specular_probe,
+            albedo_buffer);
         IBLShader::getInstance()->setUniforms();
     }
 
@@ -426,6 +429,7 @@ void LightingPasses::updateLightsInfo(scene::ICameraSceneNode * const camnode,
 void LightingPasses::renderLights(  bool has_shadow,
                                     GLuint normal_depth_texture,
                                     GLuint depth_stencil_texture,
+                                    GLuint albedo_texture,
                                     const FrameBuffer* shadow_framebuffer,
                                     GLuint specular_probe)
 {
@@ -433,7 +437,8 @@ void LightingPasses::renderLights(  bool has_shadow,
         ScopedGPUTimer timer(irr_driver->getGPUTimer(Q_ENVMAP));
         renderEnvMap(normal_depth_texture,
                      depth_stencil_texture,
-                     specular_probe);
+                     specular_probe,
+                     albedo_texture);
     }
 
     // Render sunlight if and only if track supports shadow

src/graphics/lighting_passes.hpp

@@ -34,7 +34,8 @@ private:
 
     void renderEnvMap(GLuint normal_depth_texture,
                       GLuint depth_stencil_texture,
-                      GLuint specular_probe);
+                      GLuint specular_probe,
+                      GLuint albedo_buffer);
 
     /** Generate diffuse and specular map */
     void         renderSunlight(const core::vector3df &direction,
@@ -50,6 +51,7 @@ public:
     void renderLights(  bool has_shadow,
                         GLuint normal_depth_texture,
                         GLuint depth_stencil_texture,
+                        GLuint albedo_texture,
                         const FrameBuffer* shadow_framebuffer,
                         GLuint specular_probe);
     void renderLightsScatter(GLuint depth_stencil_texture,

src/graphics/shader_based_renderer.cpp

@@ -275,10 +275,10 @@ void ShaderBasedRenderer::renderSceneDeferred(scene::ICameraSceneNode * const ca
         {
             specular_probe = m_skybox->getSpecularProbe();
         }
-
         m_lighting_passes.renderLights( hasShadow,
                                         m_rtts->getRenderTarget(RTT_NORMAL_AND_DEPTH),
                                         m_rtts->getDepthStencilTexture(),
+                                        m_rtts->getRenderTarget(RTT_COLOR),
                                         m_rtts->getShadowFrameBuffer(),
                                         specular_probe);
         PROFILER_POP_CPU_MARKER();