Set the appropriate blending function.

This may fix an issue with alpha not applying as expected.

Author: TBoshoven

MagicMirror/src/main/java/com/tomboshoven/minecraft/magicmirror/renderers/TileEntityMagicMirrorRenderer.java

@@ -18,6 +18,9 @@
 
 import javax.annotation.ParametersAreNonnullByDefault;
 
+import static org.lwjgl.opengl.GL11.GL_ONE_MINUS_SRC_ALPHA;
+import static org.lwjgl.opengl.GL11.GL_SRC_ALPHA;
+
 /**
  * Renderer for the Magic Mirror tile entity.
  */
@@ -76,6 +79,7 @@ private static void renderReflection(Reflection reflection, double x, double y,
         GlStateManager.pushMatrix();
 
         GlStateManager.enableBlend();
+        GlStateManager.blendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
         // The further away the subject is, the more faint the reflection
         float reflectionAlpha = Math.min(1f, 1.2f - (float) (distanceSq / (MAX_DISTANCE * MAX_DISTANCE)));