SuperTuxKart 1.5 upstream source (from official release tarball)

data/shaders/utils/screen_space_reflection.frag

@@ -0,0 +1,51 @@
+vec3 CalcCoordFromPosition(vec3 pos, mat4 projection_matrix,
+                           vec2 viewport_scale, vec2 viewport_offset)
+{
+    vec4 projectedCoord = projection_matrix * vec4(pos, 1.0);
+    projectedCoord.xyz /= projectedCoord.w;
+#if defined(VULKAN)
+    projectedCoord.xy   = projectedCoord.xy * 0.5 + 0.5;  // map X,Y from -1 -> +1 into 0 -> 1
+    // no Z remap here because vulkan projection matrix already gave us Z in [0..1]
+#else
+    projectedCoord.xyz  = projectedCoord.xyz * 0.5 + 0.5;
+#endif
+    // scale and offset by viewport
+    projectedCoord.xy   = projectedCoord.xy * viewport_scale + viewport_offset;
+    return projectedCoord.xyz;
+}
+
+// Fade out edges of screen buffer tex
+// 1 means full render tex, 0 means full IBL tex
+float GetEdgeFade(vec2 coords, vec2 viewport_scale, vec2 viewport_offset)
+{
+    // transform coords to viewport space
+    vec2 viewport_coords = (coords - viewport_offset) / viewport_scale;
+    float gradL = smoothstep(0.0, 0.4, viewport_coords.x);
+    float gradR = 1.0 - smoothstep(0.6, 1.0, viewport_coords.x);
+    float gradT = smoothstep(0.0, 0.4, viewport_coords.y);
+    float gradB = 1.0 - smoothstep(0.6, 1.0, viewport_coords.y);
+    return min(min(gradL, gradR), min(gradT, gradB));
+}
+
+vec2 RayCast(vec3 dir, vec3 hitCoord, mat4 projection_matrix,
+             vec2 viewport_scale, vec2 viewport_offset, sampler2DShadow depth)
+{
+    dir *= 0.5;
+    hitCoord += dir;
+
+    vec3 projectedCoord = CalcCoordFromPosition(hitCoord, projection_matrix,
+                          viewport_scale, viewport_offset);
+    float factor = 1.0;
+
+    for (int i = 0; i < 32; i++)
+    {
+        float direction = texture(depth, projectedCoord);
+        factor *= direction;
+        dir = dir * (0.5 + 0.5 * factor);
+        hitCoord += dir * (2. * direction - 1.);
+        projectedCoord = CalcCoordFromPosition(hitCoord, projection_matrix,
+                         viewport_scale, viewport_offset);
+    }
+
+    return projectedCoord.xy;
+}