Use opaque rendering pipeline for alpha hash materials

This has several benefits:

- Transparency sorting issues inherent to alpha blending no longer occur.
- Alpha hash materials can now cast shadows (also works with
  GeometryInstance3D Transparency's property for alpha hash materials).
- Higher performance.

2 files changed, 6 insertions, 0 deletions

diff --git a/servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp b/servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp
index cfb30ef2f3..615e2e9b7c 100644
--- a/servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp
+++ b/servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp
@@ -111,6 +111,9 @@ void SceneShaderForwardClustered::ShaderData::set_code(const String &p_code) {
 
 	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
 	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
+	// Use alpha clip pipeline for alpha hash/dither.
+	// This prevents sorting issues inherent to alpha blending and allows such materials to cast shadows.
+	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
 	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_pre_pass;
 
 	actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;
diff --git a/servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp b/servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp
index f66ad529de..321e03cdff 100644
--- a/servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp
+++ b/servers/rendering/renderer_rd/forward_mobile/scene_shader_forward_mobile.cpp
@@ -112,6 +112,9 @@ void SceneShaderForwardMobile::ShaderData::set_code(const String &p_code) {
 
 	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
 	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
+	// Use alpha clip pipeline for alpha hash/dither.
+	// This prevents sorting issues inherent to alpha blending and allows such materials to cast shadows.
+	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
 	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_pre_pass;
 
 	// actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;