Squashed 'external/imgui/' content from commit 02e9b8cac

git-subtree-dir: external/imgui
git-subtree-split: 02e9b8cacde285c5f9040adf212703cc3810bd97

backends/sdlgpu3/shader.frag

@@ -0,0 +1,15 @@
+#version 450 core
+layout(location = 0) out vec4 fColor;
+
+layout(set=2, binding=0) uniform sampler2D sTexture;
+
+layout(location = 0) in struct
+{
+    vec4 Color;
+    vec2 UV;
+} In;
+
+void main()
+{
+    fColor = In.Color * texture(sTexture, In.UV.st);
+}