Disabled external gits

cs440-acg/ext/nanogui/resources/imageview_vertex.metal

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+#include <metal_stdlib>
+
+using namespace metal;
+
+struct VertexOut {
+    float4 position_image [[position]];
+    float2 position_background;
+    float2 uv;
+};
+
+vertex VertexOut vertex_main(const device float2 *position,
+                             constant float4x4 &matrix_image,
+                             constant float4x4 &matrix_background,
+                             uint id [[vertex_id]]) {
+    float4 p = float4(position[id], 0.f, 1.f);
+    VertexOut vert;
+    vert.position_image = matrix_image * p;
+    vert.position_background = (matrix_background * p).xy;
+    vert.uv = p.xy;
+    return vert;
+}