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

3 files changed, 4 insertions, 4 deletions

diff --git a/source/blender/draw/engines/overlay/shaders/background_frag.glsl b/source/blender/draw/engines/overlay/shaders/background_frag.glsl
index 52052d414f8..19313c0415b 100644
--- a/source/blender/draw/engines/overlay/shaders/background_frag.glsl
+++ b/source/blender/draw/engines/overlay/shaders/background_frag.glsl
@@ -38,8 +38,8 @@ void main()
    * This removes the alpha channel and put the background behind reference images
    * while masking the reference images by the render alpha.
    */
-  float alpha = texture(colorBuffer, uvcoordsvar.st).a;
-  float depth = texture(depthBuffer, uvcoordsvar.st).r;
+  float alpha = texture(colorBuffer, uvcoordsvar.xy).a;
+  float depth = texture(depthBuffer, uvcoordsvar.xy).r;
 
   vec3 bg_col;
   vec3 col_high;
diff --git a/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl b/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
index 0e4757f8ea8..19d54a57479 100644
--- a/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
+++ b/source/blender/draw/engines/overlay/shaders/outline_detect_frag.glsl
@@ -169,7 +169,7 @@ void diag_dir(bvec4 edges1, bvec4 edges2, out vec2 line_start, out vec2 line_end
 
 void main()
 {
-  uint ref = textureLod(outlineId, uvcoordsvar.st, 0.0).r;
+  uint ref = textureLod(outlineId, uvcoordsvar.xy, 0.0).r;
   uint ref_col = ref;
 
   vec2 uvs = gl_FragCoord.xy * sizeViewportInv.xy;
diff --git a/source/blender/draw/engines/overlay/shaders/volume_gridlines_vert.glsl b/source/blender/draw/engines/overlay/shaders/volume_gridlines_vert.glsl
index f714646fe40..507beb8a418 100644
--- a/source/blender/draw/engines/overlay/shaders/volume_gridlines_vert.glsl
+++ b/source/blender/draw/engines/overlay/shaders/volume_gridlines_vert.glsl
@@ -53,7 +53,7 @@ vec4 flag_to_color(uint flag)
   if (bool(flag & uint(16))) {
     color.rgb += vec3(0.9, 0.3, 0.0); /* orange */
   }
-  if (color.rgb == vec3(0.0)) {
+  if (is_zero(color.rgb)) {
     color.rgb += vec3(0.5, 0.0, 0.0); /* medium red */
   }
   return color;