The fade masks textures should use an alpha format

So they don't get effected by the texture format set by the screen depth
GL_RGB5_A1 from 16-bit was removing all alpha from the texture

src/hardware/r_opengl/r_opengl.c

@@ -1470,6 +1470,26 @@ EXPORT void HWRAPI(SetTexture) (FTextureInfo *pTexInfo)
 			else
 				pglTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
 		}
+		else if (pTexInfo->grInfo.format == GR_TEXFMT_ALPHA_8)
+		{
+			//pglTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+			if (MipMap)
+			{
+				pgluBuild2DMipmaps(GL_TEXTURE_2D, GL_ALPHA, w, h, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+#ifdef GL_TEXTURE_MIN_LOD
+				pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_LOD, 0);
+#endif
+#ifdef GL_TEXTURE_MAX_LOD
+				if (pTexInfo->flags & TF_TRANSPARENT)
+					pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 0); // No mippmaps on transparent stuff
+				else
+					pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LOD, 4);
+#endif
+				//pglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_LINEAR_MIPMAP_LINEAR);
+			}
+			else
+				pglTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, ptex);
+		}
 		else
 		{
 			if (MipMap)