Clean up UI, work on tutorial

src/UiManager.cpp

@@ -402,15 +402,16 @@ namespace ZL {
 	void UiStaticImage::draw(Renderer& renderer) const {
 		if (!texture) return;
 
-		const float alpha = (fadeInEnabled && fadeInDurationMs > 0.0f)
+		const float fadeAlpha = (fadeInEnabled && fadeInDurationMs > 0.0f)
 			? std::clamp(fadeInElapsedMs / fadeInDurationMs, 0.0f, 1.0f)
 			: 1.0f;
+		const float finalAlpha = alpha * fadeAlpha;
 
 		renderer.RenderUniform1i(textureUniformName, 0);
-		renderer.RenderUniform1f("uAlpha", alpha);
+		renderer.RenderUniform1f("uAlpha", finalAlpha);
 		glBindTexture(GL_TEXTURE_2D, texture->getTexID());
 		renderer.DrawVertexRenderStruct(mesh);
-		if (alpha < 1.0f) {
+		if (finalAlpha < 1.0f) {
 			renderer.RenderUniform1f("uAlpha", 1.0f); // restore for subsequent draws
 		}
 	}