Eevee: SSR: Add support for planar probes.

This add the possibility to use planar probe informations to create SSR.
This has 2 advantages:
- Tracing is less expensive since the hit is found much quicker.
- We have much less artifact due to missing information.

There is still area for improvement.

1 files changed, 5 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/lightprobe_planar_downsample_frag.glsl b/source/blender/draw/engines/eevee/shaders/lightprobe_planar_downsample_frag.glsl
index fa70fb5590f..c2ef085ca01 100644
--- a/source/blender/draw/engines/eevee/shaders/lightprobe_planar_downsample_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lightprobe_planar_downsample_frag.glsl
@@ -13,8 +13,9 @@ out vec4 FragColor;
 void main()
 {
 	/* Reconstructing Target uvs like this avoid missing pixels */
-	vec2 uvs = floor(gl_FragCoord.xy) * 2.0 * texelSize + texelSize;
+	vec2 uvs = gl_FragCoord.xy * 2.0 / vec2(textureSize(source, 0).xy);
 
+#if 0 /* Slower and does not match the main framebuffer downsampling. */
 	/* Downsample with a 4x4 box filter */
 	vec4 d = texelSize.xyxy * vec4(-1, -1, +1, +1);
 
@@ -24,4 +25,7 @@ void main()
 	FragColor += texture(source, vec3(uvs + d.zw, layer)).rgba;
 
 	FragColor /= 4.0;
+#endif
+
+	FragColor = texture(source, vec3(uvs, layer));
 }
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