1 files changed, 100 insertions, 0 deletions

diff --git a/source/blender/gpu/metal/mtl_primitive.hh b/source/blender/gpu/metal/mtl_primitive.hh
new file mode 100644
index 00000000000..5aa7a533b95
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+++ b/source/blender/gpu/metal/mtl_primitive.hh
@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup gpu
+ *
+ * Encapsulation of Frame-buffer states (attached textures, viewport, scissors).
+ */
+
+#pragma once
+
+#include "BLI_assert.h"
+
+#include "GPU_primitive.h"
+
+#include <Metal/Metal.h>
+
+namespace blender::gpu {
+
+/** Utility functions **/
+static inline MTLPrimitiveTopologyClass mtl_prim_type_to_topology_class(MTLPrimitiveType prim_type)
+{
+  switch (prim_type) {
+    case MTLPrimitiveTypePoint:
+      return MTLPrimitiveTopologyClassPoint;
+    case MTLPrimitiveTypeLine:
+    case MTLPrimitiveTypeLineStrip:
+      return MTLPrimitiveTopologyClassLine;
+    case MTLPrimitiveTypeTriangle:
+    case MTLPrimitiveTypeTriangleStrip:
+      return MTLPrimitiveTopologyClassTriangle;
+  }
+  return MTLPrimitiveTopologyClassUnspecified;
+}
+
+static inline MTLPrimitiveType gpu_prim_type_to_metal(GPUPrimType prim_type)
+{
+  switch (prim_type) {
+    case GPU_PRIM_POINTS:
+      return MTLPrimitiveTypePoint;
+    case GPU_PRIM_LINES:
+    case GPU_PRIM_LINES_ADJ:
+    case GPU_PRIM_LINE_LOOP:
+      return MTLPrimitiveTypeLine;
+    case GPU_PRIM_LINE_STRIP:
+    case GPU_PRIM_LINE_STRIP_ADJ:
+      return MTLPrimitiveTypeLineStrip;
+    case GPU_PRIM_TRIS:
+    case GPU_PRIM_TRI_FAN:
+    case GPU_PRIM_TRIS_ADJ:
+      return MTLPrimitiveTypeTriangle;
+    case GPU_PRIM_TRI_STRIP:
+      return MTLPrimitiveTypeTriangleStrip;
+    case GPU_PRIM_NONE:
+      return MTLPrimitiveTypePoint;
+  };
+}
+
+/* Certain primitive types are not supported in Metal, and require emulation.
+ * `GPU_PRIM_LINE_LOOP` and  `GPU_PRIM_TRI_FAN` required index buffer patching.
+ * Adjacency types do not need emulation as the input structure is the same,
+ * and access is controlled from the vertex shader through SSBO vertex fetch.
+ * -- These Adj cases are only used in geometry shaders in OpenGL. */
+static inline bool mtl_needs_topology_emulation(GPUPrimType prim_type)
+{
+
+  BLI_assert(prim_type != GPU_PRIM_NONE);
+  switch (prim_type) {
+    case GPU_PRIM_LINE_LOOP:
+    case GPU_PRIM_TRI_FAN:
+      return true;
+    default:
+      return false;
+  }
+  return false;
+}
+
+static inline bool mtl_vertex_count_fits_primitive_type(uint32_t vertex_count,
+                                                        MTLPrimitiveType prim_type)
+{
+  if (vertex_count == 0) {
+    return false;
+  }
+
+  switch (prim_type) {
+    case MTLPrimitiveTypeLineStrip:
+      return (vertex_count > 1);
+    case MTLPrimitiveTypeLine:
+      return (vertex_count % 2 == 0);
+    case MTLPrimitiveTypePoint:
+      return (vertex_count > 0);
+    case MTLPrimitiveTypeTriangle:
+      return (vertex_count % 3 == 0);
+    case MTLPrimitiveTypeTriangleStrip:
+      return (vertex_count > 2);
+  }
+  BLI_assert(false);
+  return false;
+}
+
+}  // namespace blender::gpu
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