diff --git a/samples/api/texture_loading/texture_loading.cpp b/samples/api/texture_loading/texture_loading.cpp
index 9abe28c..fdcc76c 100644
--- a/samples/api/texture_loading/texture_loading.cpp
+++ b/samples/api/texture_loading/texture_loading.cpp
@@ -902,17 +902,26 @@ void TextureLoading::prepare_uniform_buffers_point()
 		VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT,
 		VMA_MEMORY_USAGE_CPU_TO_GPU);
 
-	update_uniform_buffers_point(60, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 2);
+	update_uniform_buffers_point(60, -0.5, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 2);
 }
 
 
 void global_update_mvp(float fov, float x, float y, float z, float sx, float sy, float sz, float rotx, float roty, float rotz, float camx, float camy, float camz)
 {
-	TextureLoading::Get()->update_uniform_buffers_point(fov, x, y, z, sx, sy, sz, rotx, roty, rotz, camx, camy, camz);
+	TextureLoading* self = TextureLoading::Get();
+	if (self != nullptr)
+	{
+		self->update_uniform_buffers_point(fov, x, y, z, sx, sy, sz, rotx, roty, rotz, camx, camy, camz);
+	}
 }
 
 void TextureLoading::update_uniform_buffers_point(float fov, float x, float y, float z, float sx, float sy, float sz, float rotx, float roty, float rotz, float camx, float camy, float camz)
 {
+	if (!prepared)
+	{
+		return;
+	}
+
 	std::unique_lock<std::mutex> lock(mtx_mvp);
 	ubo_vs_point.projection = glm::perspective(glm::radians(fov), static_cast<float>(width) / static_cast<float>(height), 0.001f, 256.0f);