Update raylib.h

src/raylib.h

@@ -748,10 +748,11 @@ typedef enum {
 // Material map index
 typedef enum {
     MATERIAL_MAP_ALBEDO = 0,        // Albedo material (same as: MATERIAL_MAP_DIFFUSE)
-    MATERIAL_MAP_METALNESS,         // Metalness material (same as: MATERIAL_MAP_SPECULAR)
     MATERIAL_MAP_NORMAL,            // Normal material
+    MATERIAL_MAP_METALNESS,         // Metalness material (same as: MATERIAL_MAP_SPECULAR)
     MATERIAL_MAP_ROUGHNESS,         // Roughness material
     MATERIAL_MAP_OCCLUSION,         // Ambient occlusion material
+    MATERIAL_MAP_MRA,               // Metalness-Roughness-AmbientOcclusion material, combined in a single image (RBG channels)
     MATERIAL_MAP_EMISSION,          // Emission material
     MATERIAL_MAP_HEIGHT,            // Heightmap material
     MATERIAL_MAP_CUBEMAP,           // Cubemap material (NOTE: Uses GL_TEXTURE_CUBE_MAP)