Metal: Initial Implementation of Metal Backend for GPU Module.

Adding WITH_METAL option to CMAKE to guard compilation for macOS only. Implemented stub METALBackend to mirror GPUBackend interface and added capabilities initialisation, along with API initialisation paths.

Global rendering coordination commands added to backend with GPU_render_begin and GPU_render_end() commands globally wrapping GPU work. This is required for Metal to ensure temporary resources are generated within an NSAutoReleasePool and freed accordingly.

Authored by Apple: Michael Parkin-White, Vil Harvey, Marco Giordano, Michael Jones, Morteza Mostajabodaveh, Jason Fielder

Ref T96261

Reviewed By: fclem

Maniphest Tasks: T96261

Differential Revision: https://developer.blender.org/D14293

2 files changed, 12 insertions, 1 deletions

diff --git a/source/blender/gpu/opengl/gl_backend.cc b/source/blender/gpu/opengl/gl_backend.cc
index 883f9403920..2c9cbdb99d8 100644
--- a/source/blender/gpu/opengl/gl_backend.cc
+++ b/source/blender/gpu/opengl/gl_backend.cc
@@ -140,7 +140,7 @@ void GLBackend::platform_init()
     }
   }
 
-  GPG.init(device, os, driver, support_level, vendor, renderer, version);
+  GPG.init(device, os, driver, support_level, GPU_BACKEND_OPENGL, vendor, renderer, version);
 }
 
 void GLBackend::platform_exit()
@@ -418,6 +418,12 @@ static void detect_workarounds()
       (strstr(renderer, "HD Graphics 4400") || strstr(renderer, "HD Graphics 4600"))) {
     GCaps.shader_storage_buffer_objects_support = false;
   }
+
+  /* Metal-related Workarounds. */
+
+  /* Minimum Per-Vertex stride is 1 byte for OpenGL. */
+  GCaps.minimum_per_vertex_stride = 1;
+
 }  // namespace blender::gpu
 
 /** Internal capabilities. */
diff --git a/source/blender/gpu/opengl/gl_backend.hh b/source/blender/gpu/opengl/gl_backend.hh
index e72726d9c7b..29249111294 100644
--- a/source/blender/gpu/opengl/gl_backend.hh
+++ b/source/blender/gpu/opengl/gl_backend.hh
@@ -136,6 +136,11 @@ class GLBackend : public GPUBackend {
     glBindBuffer(GL_DRAW_INDIRECT_BUFFER, 0);
   }
 
+  /* Render Frame Coordination */
+  void render_begin(void) override{};
+  void render_end(void) override{};
+  void render_step(void) override{};
+
  private:
   static void platform_init();
   static void platform_exit();