fixed light flickering when rotating an object.

Resources/Shaders/postfx_bright_frag.glsl

@@ -9,7 +9,9 @@ uniform float threshold = 1.0;
 void main() {
     vec3 c = texture(sceneTex, TexCoord).rgb;
     float luma = dot(c, vec3(0.2125, 0.7154, 0.0721));
-    float bright = max(luma - threshold, 0.0);
-    vec3 masked = c * step(0.0, bright);
+    float knee = 0.25;
+    float w = clamp((luma - threshold) / max(knee, 1e-4), 0.0, 1.0);
+    w = w * w * (3.0 - 2.0 * w);
+    vec3 masked = c * w;
     FragColor = vec4(masked, 1.0);
 }