sky: improve sun scatter

doc/Sky.md

@@ -34,7 +34,7 @@ Resources:
 
 ## Tasks
 
-- [ ] Light scatter
+- [x] Light scatter
 - [ ] Atmosphere effect
 - [ ] improve fog color
 - [ ] Lens flare

src/main/java/de/bixilon/minosoft/gui/rendering/sky/planet/scatter/SunScatterRenderer.kt

@@ -56,10 +56,9 @@ class SunScatterRenderer(
     }
 
     private fun calculateIntensity(progress: Float): Float {
-        val delta = (abs(progress - 0.5f) * 2.0f)
-        val sine = minOf(sin(delta * PI.toFloat() / 2.0f), 0.6f)
+        val delta = (abs(progress) * 2.0f)
 
-        return 1.0f - sine
+        return maxOf(sin(delta * PI.toFloat() / 2.0f), 0.5f)
     }
 
     private fun calculateSunPosition(): Vec3 {
@@ -79,9 +78,9 @@ class SunScatterRenderer(
         if (!sky.profile.sunScatter || sky.time.phase == DayPhases.DAY || sky.time.phase == DayPhases.NIGHT || !sky.properties.sun) {
             return
         }
+        shader.use()
         if (timeUpdate) {
             calculateMatrix()
-            shader.use()
             shader.setMat4("uScatterMatrix", matrix)
             shader.setFloat("uIntensity", calculateIntensity(sky.time.progress))
             shader.setVec3("uSunPosition", calculateSunPosition())

src/main/resources/assets/minosoft/rendering/shader/sky/scatter/sun/sun.fsh

@@ -36,11 +36,11 @@ uniform vec3 uSunPosition;
 
 #define END_DISTANCE MAX_DISTANCE - 0.2f
 
-#define YELLOWISH vec3(0.9f, 0.8f, 0.25f)
+#define YELLOWISH vec3(1.0f, 0.6f, 0.15f)
 #define REDISH vec3(1.0f, 0.4f, 0.05f)
 
 void main() {
-    foutColor = vec4(REDISH, uIntensity * 0.8f);
+    foutColor = vec4(REDISH, uIntensity);
     float distance = length(uSunPosition - finFragmentPosition);
 
     float distanceMultiplier = 0.0f;