GPU: Texture: Expose depth dimension extent

This function was not exposed outside of internal GPU module.

Renaming `draw::Texture::depth()` to `is_depth` for consistency
and removing the ambiguity.

source/blender/draw/intern/DRW_gpu_wrapper.hh

@@ -766,12 +766,17 @@ class Texture : NonCopyable {
     return GPU_texture_height(tx_);
   }
 
+  int depth() const
+  {
+    return GPU_texture_depth(tx_);
+  }
+
   int pixel_count() const
   {
     return GPU_texture_width(tx_) * GPU_texture_height(tx_);
   }
 
-  bool depth() const
+  bool is_depth() const
   {
     return GPU_texture_has_depth_format(tx_);
   }

source/blender/gpu/GPU_texture.h

@@ -940,6 +940,12 @@ int GPU_texture_width(const GPUTexture *texture);
  */
 int GPU_texture_height(const GPUTexture *texture);
 
+/**
+ * Return the depth of \a tex . Correspond to number of layers for 2D array texture.
+ * NOTE: return 0 for 1D & 2D textures.
+ */
+int GPU_texture_depth(const GPUTexture *texture);
+
 /**
  * Return the number of layers of \a tex . Return 1 if the texture is not layered.
  */

source/blender/gpu/intern/gpu_texture.cc

@@ -716,6 +716,11 @@ int GPU_texture_height(const GPUTexture *tex)
   return reinterpret_cast<const Texture *>(tex)->height_get();
 }
 
+int GPU_texture_depth(const GPUTexture *tex)
+{
+  return reinterpret_cast<const Texture *>(tex)->depth_get();
+}
+
 int GPU_texture_layer_count(const GPUTexture *tex)
 {
   return reinterpret_cast<const Texture *>(tex)->layer_count();