Currently following code block is added in MetalContext.drawIndexedQuads()
```
   if (tex0 != nil) {
        id<MTLTexture> tex = [tex0 getTexture];
        [renderEncoder useResource:tex usage:MTLResourceUsageRead];
    }
```
This call is required for text rendering but has side effect that it will be applied to any texture from any shader that was set last.
This call should be moved to better place where it's execution scope is limited to it's need.