From 63c5ffa8ff30c296ee3278c821cfa55cfce2605f Mon Sep 17 00:00:00 2001
From: Rye Mutt <rye@alchemyviewer.org>
Date: Mon, 7 Jun 2021 17:02:45 -0400
Subject: [PATCH] Port rainbow fix to class1 deferred sky fragment shader
---
.../shaders/class1/deferred/skyF.glsl | 23 +++++++++++++------
1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl b/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
index 810daae3200..da07f195772 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/skyF.glsl
@@ -48,14 +48,23 @@ out vec4 frag_data[3];
vec3 rainbow(float d)
{
- // 'Interesting' values of d are -0.75 .. -0.825, i.e. when view vec nearly opposite of sun vec
- // Rainbox tex is mapped with REPEAT, so -.75 as tex coord is same as 0.25. -0.825 -> 0.175. etc.
- // SL-13629
- // Unfortunately the texture is inverted, so we need to invert the y coord, but keep the 'interesting'
- // part within the same 0.175..0.250 range, i.e. d = (1 - d) - 1.575
- d = clamp(-0.575 - d, 0.0, 1.0);
+ // d is the dot product of view and sun directions, so ranging -1.0..1.0
+ // 'interesting' values of d are the range -0.75..-0.825, when view is nearly opposite of sun vec
+ // Rainbox texture mode is GL_REPEAT, so tc of -.75 is equiv to 0.25, -0.825 equiv to 0.175.
+
+ // SL-13629 Rainbow texture has colors within the correct .175...250 range, but order is inverted.
+ // Rather than replace the texture, we mirror and translate the y tc to keep the colors within the
+ // interesting range, but in reversed order: i.e. d = (1 - d) - 1.575
+ d = clamp(-0.575 - d, 0.0, 1.0);
+
+ // With the colors in the lower 1/4 of the texture, inverting the coords leaves most of it inaccessible.
+ // So, we can stretch the texcoord above the colors (ie > 0.25) to fill the entire remaining coordinate
+ // space. This improves gradation, reduces banding within the rainbow interior. (1-0.25) / (0.425/0.25) = 4.2857
+ float interior_coord = max(0.0, d - 0.25) * 4.2857;
+ d = clamp(d, 0.0, 0.25) + interior_coord;
+
float rad = (droplet_radius - 5.0f) / 1024.0f;
- return pow(texture2D(rainbow_map, vec2(rad+0.5, d)).rgb, vec3(1.8)) * moisture_level;
+ return pow(texture2D(rainbow_map, vec2(rad, d)).rgb, vec3(1.8)) * moisture_level;
}
vec3 halo22(float d)
--
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