Move premultiplied alpha to shader

data/shaders/simple_particle.frag

@@ -11,6 +11,7 @@ out vec4 FragColor;
 void main(void)
 {
     float billboard_alpha = mix(1.0, texture(tex, tc).a, billboard);
+    vec4 color = texture(tex, tc);
 #if defined(Advanced_Lighting_Enabled)
     vec2 xy = gl_FragCoord.xy / u_screen;
     float FragZ = gl_FragCoord.z;
@@ -21,5 +22,6 @@ void main(void)
 #else
     float alpha = 1.0;
 #endif
-    FragColor = texture(tex, tc) * billboard_alpha * pc * alpha;
+    color = vec4(color.rgb * color.a, color.a);
+    FragColor = color * billboard_alpha * pc * alpha;
 }

src/graphics/stk_texture.cpp

@@ -207,25 +207,6 @@ void STKTexture::formatConversion(uint8_t* data, unsigned int* format,
         }
     }
 #endif
-    if (isPremulAlpha() && !m_single_channel)
-    {
-        for (unsigned int i = 0; i < w * h; i++)
-        {
-            float alpha = data[4 * i + 3];
-            if (alpha > 0.0f)
-            {
-                alpha /= 255.0f;
-
-                if (CVS->isDeferredEnabled())
-                {
-                    alpha = pow(alpha, 1.0f / 2.2f);
-                }
-            }
-            data[i * 4] = (uint8_t)(data[i * 4] * alpha);
-            data[i * 4 + 1] = (uint8_t)(data[i * 4 + 1] * alpha);
-            data[i * 4 + 2] = (uint8_t)(data[i * 4 + 2] * alpha);
-        }
-    }
 #endif   // !SERVER_ONLY
 }   // formatConversion