Added setTexture validation to check for read back texture.

src/bgfx.cpp

@@ -3822,6 +3822,13 @@ namespace bgfx
 		BGFX_CHECK_HANDLE("setTexture/UniformHandle", s_ctx->m_uniformHandle, _sampler);
 		BGFX_CHECK_HANDLE_INVALID_OK("setTexture/TextureHandle", s_ctx->m_textureHandle, _handle);
 		BX_ASSERT(_stage < g_caps.limits.maxTextureSamplers, "Invalid stage %d (max %d).", _stage, g_caps.limits.maxTextureSamplers);
+
+		const TextureRef& ref = s_ctx->m_textureRef[_handle.idx];
+		BX_ASSERT(!ref.isReadBack()
+			, "Can't sample from texture which was created with BGFX_TEXTURE_READ_BACK. This is CPU only texture."
+			);
+		BX_UNUSED(ref);
+
 		BGFX_ENCODER(setTexture(_stage, _sampler, _handle, _flags) );
 	}