Metal: Make GLSL shader source MSL compliant also

Metal shading language follows the C++ 14 standard and in some cases requires a greater level of explicitness than GLSL. There are also some small language differences:

- Explicit type-casts (C++ requirements)
- Explicit constant values (C++ requirements, e.g. floating point values using 0.0 instead of 0).
- Metal/OpenGL compatibility paths
- GLSL Function prototypes
- Explicit accessors for vector types when sampling textures.

Authored by Apple: Michael Parkin-White

Ref T96261

Reviewed By: fclem

Maniphest Tasks: T96261

Differential Revision: https://developer.blender.org/D14378

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/gpu/intern/gpu_shader.cc b/source/blender/gpu/intern/gpu_shader.cc
index ac8e98a4a21..b434cfbbb0e 100644
--- a/source/blender/gpu/intern/gpu_shader.cc
+++ b/source/blender/gpu/intern/gpu_shader.cc
@@ -88,6 +88,16 @@ static void standard_defines(Vector<const char *> &sources)
   else if (GPU_type_matches(GPU_DEVICE_ANY, GPU_OS_UNIX, GPU_DRIVER_ANY)) {
     sources.append("#define OS_UNIX\n");
   }
+  /* API Definition */
+  eGPUBackendType backend = GPU_backend_get_type();
+  switch (backend) {
+    case GPU_BACKEND_OPENGL:
+      sources.append("#define GPU_OPENGL\n");
+      break;
+    default:
+      BLI_assert(false && "Invalid GPU Backend Type");
+      break;
+  }
 
   if (GPU_crappy_amd_driver()) {
     sources.append("#define GPU_DEPRECATED_AMD_DRIVER\n");