Repo created

libs/shaders/Metal/shaders_lib.metal

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+#include <metal_stdlib>
+#include <simd/simd.h>
+
+using namespace metal;
+
+float4 ApplyPivotTransform(float4 pivot, float4x4 pivotTransform, float pivotRealZ)
+{
+  float4 transformedPivot = pivot;
+  float w = transformedPivot.w;
+  transformedPivot.xyw = (pivotTransform * float4(transformedPivot.xy, pivotRealZ, w)).xyw;
+  transformedPivot.z *= transformedPivot.w / w;
+  return transformedPivot;
+}
+
+float2 CalcLineTransformedAxisPos(float2 originalAxisPos, float2 shiftedPos, float4x4 modelView, float halfWidth)
+{
+  float2 p = (float4(shiftedPos, 0.0, 1.0) * modelView).xy;
+  float2 d = p - originalAxisPos;
+  if (dot(d, d) != 0.0)
+    return originalAxisPos + normalize(d) * halfWidth;
+  else
+    return originalAxisPos;
+}
+
+float4 ApplyBillboardPivotTransform(float4 pivot, float4x4 pivotTransform, float pivotRealZ, float2 offset)
+{
+  float logicZ = pivot.z / pivot.w;
+  float4 transformedPivot = pivotTransform * float4(pivot.xy, pivotRealZ, pivot.w);
+  float4 scale = pivotTransform * float4(1.0, -1.0, 0.0, 1.0);
+  return float4(transformedPivot.xy / transformedPivot.w, logicZ, 1.0) + float4(offset / scale.w * scale.x, 0.0, 0.0);
+}