REVIEWED: GenTextureCubemap(), use rlgl functionality only

Function has been reviewed to avoid any direct OpenGL call and use rlgl functionality, also, GenDrawCube() has been replaced by the internal batch system with DrawCube().

WARNING: rlEnableTexture() call must be issued after enabling the current framebuffer when using batch mechanism because it includes a set of security checks to avoid batch overflow and push/pop matrix operations.

src/rlgl.h

@@ -3327,8 +3327,8 @@ TextureCubemap GenTextureCubemap(Shader shader, Texture2D panorama, int size, in
     };
 
     rlEnableShader(shader.id);
-    glActiveTexture(GL_TEXTURE0);
-    glBindTexture(GL_TEXTURE_2D, panorama.id);
+    //glActiveTexture(GL_TEXTURE0);
+    //glBindTexture(GL_TEXTURE_2D, panorama.id);
 
     rlViewport(0, 0, size, size);   // Set viewport to current fbo dimensions
 
@@ -3338,8 +3338,14 @@ TextureCubemap GenTextureCubemap(Shader shader, Texture2D panorama, int size, in
         rlFramebufferAttach(fbo, cubemap.id, RL_ATTACHMENT_COLOR_CHANNEL0, RL_ATTACHMENT_CUBEMAP_POSITIVE_X + i);
 
         rlEnableFramebuffer(fbo);
+        rlEnableTexture(panorama.id);   // WARNING: It must be called after enabling current framebuffer if using internal batch system!
+        
         rlClearScreenBuffers();
-        GenDrawCube();
+        //GenDrawCube();
+        
+        // Using internal batch system instead of raw OpenGL cube creating+drawing
+        DrawCubeV(Vector3Zero(), Vector3One(), WHITE);
+        DrawRenderBatch(RLGL.currentBatch);
     }
     //------------------------------------------------------------------------------------------