EEVEE: Lookdev: Add support for partially blurred background

This is using the GGX probe as background. This has the drawback of
having the resolution choosed in the indirect lighting setting.
The blurring is not really high-quality.

The pros is that it has a simple implementation and is fast to evaluate.

This patch also fades the background alpha to make overlay engine draw the
default background color in the correct color space. Removing one colorspace
hack.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D6895

1 files changed, 11 insertions, 4 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/default_world_frag.glsl b/source/blender/draw/engines/eevee/shaders/default_world_frag.glsl
index 41e103609f3..1faa02fd354 100644
--- a/source/blender/draw/engines/eevee/shaders/default_world_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/default_world_frag.glsl
@@ -4,11 +4,12 @@ uniform vec3 color;
 
 out vec4 FragColor;
 
-#ifdef LOOKDEV
+#if defined(LOOKDEV_BG) || defined(LOOKDEV)
+
 uniform mat3 StudioLightMatrix;
 uniform sampler2D image;
-uniform float studioLightBackground = 1.0;
 uniform float studioLightIntensity = 1.0;
+uniform float studioLightBlur = 0.0;
 in vec3 viewPosition;
 
 #  define M_PI 3.14159265358979323846
@@ -49,11 +50,17 @@ vec4 node_tex_environment_equirectangular(vec3 co, sampler2D ima)
 void main()
 {
   vec3 background_color;
-#ifdef LOOKDEV
+
+#if defined(LOOKDEV_BG)
+  vec3 worldvec = background_transform_to_world(viewPosition);
+  background_color = probe_evaluate_world_spec(worldvec, studioLightBlur).rgb;
+  background_color *= studioLightIntensity;
+
+#elif defined(LOOKDEV)
   vec3 worldvec = background_transform_to_world(viewPosition);
   background_color = node_tex_environment_equirectangular(StudioLightMatrix * worldvec, image).rgb;
   background_color *= studioLightIntensity;
-  background_color = mix(color, background_color, studioLightBackground);
+
 #else
   background_color = color;
 #endif