From 26b48751894c71b94ccf46bdf864d30fc29fa739 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 11 Mar 2022 12:14:55 +0200
Subject: [PATCH] Detect and export alpha cutoff in Blender

---
 blender/io_mspgl/export_material.py | 56 +++++++++++++++++++++++++----
 blender/io_mspgl/material.py        |  1 +
 2 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/blender/io_mspgl/export_material.py b/blender/io_mspgl/export_material.py
index b0df347f..36dbdc69 100644
--- a/blender/io_mspgl/export_material.py
+++ b/blender/io_mspgl/export_material.py
@@ -1,3 +1,31 @@
+def create_shadow_method(tech_res, material, resources, detail):
+	from .datafile import Statement
+
+	color_prop = next((p for p in material.properties if p.keyword and "color" in p.keyword), None)
+
+	st = Statement("method", "shadow"+detail)
+	if material.alpha_cutoff>0.0 and color_prop and 'A' in color_prop.tex_channels:
+		st.sub.append(tech_res.create_reference_statement("shader", resources["occluder{}_masked.shader".format(detail)]))
+		ss = Statement("texture", "alpha_map")
+
+		from .export_texture import TextureExporter
+		from .export_texture import SamplerExporter
+		texture_export = TextureExporter()
+		sampler_export = SamplerExporter()
+
+		tex_res = resources[texture_export.get_texture_name(color_prop.texture, color_prop.tex_channels)]
+		ss.sub.append(tech_res.create_reference_statement("texture", tex_res))
+		ss.sub.append(tech_res.create_reference_statement("sampler", resources[sampler_export.get_sampler_name(color_prop.texture)]))
+		st.sub.append(ss)
+
+		ss = Statement("uniforms")
+		ss.sub.append(Statement("uniform", "alpha_cutoff", material.alpha_cutoff))
+		st.sub.append(ss)
+	else:
+		st.sub.append(Statement("shader", "occluder{}.glsl.shader".format(detail)))
+
+	return st;
+
 def create_technique_resource(material, resources):
 	from .datafile import Resource, Statement, Token
 	tech_res = Resource(material.name+".tech", "technique")
@@ -49,13 +77,8 @@ def create_technique_resource(material, resources):
 		tech_res.statements.append(st)
 
 		if material.cast_shadows:
-			st = Statement("method", "shadow")
-			st.sub.append(Statement("shader", "occluder.glsl.shader"))
-			tech_res.statements.append(st)
-
-			st = Statement("method", "shadow_thsm")
-			st.sub.append(Statement("shader", "occluder_thsm.glsl.shader"))
-			tech_res.statements.append(st)
+			tech_res.statements.append(create_shadow_method(tech_res, material, resources, ""));
+			tech_res.statements.append(create_shadow_method(tech_res, material, resources, "_thsm"));
 
 	return tech_res
 
@@ -91,6 +114,12 @@ class MaterialExporter:
 			else:
 				resources[mat_name] = None
 
+		if material.cast_shadows and material.alpha_cutoff>0.0:
+			for detail in ("", "_thsm"):
+				shader_name = "occluder{}_masked.shader".format(detail)
+				if shader_name not in resources:
+					resources[shader_name] = self.export_shader(shader_name, "occluder{}.glsl".format(detail), {"use_alpha_cutoff":True}, resources)
+
 	def export_technique(self, material, resources):
 		from .material import Material
 		if type(material)!=Material:
@@ -115,6 +144,8 @@ class MaterialExporter:
 			from .export_texture import SamplerExporter
 			sampler_export = SamplerExporter()
 			mat_res.statements.append(mat_res.create_reference_statement("sampler", resources[sampler_export.get_sampler_name(textures[0])]))
+		if material.alpha_cutoff>0.0:
+			mat_res.statements.append(Statement("alpha_cutoff", material.alpha_cutoff))
 
 		return mat_res
 
@@ -132,6 +163,17 @@ class MaterialExporter:
 		else:
 			return Statement(prop.keyword, prop.value)
 
+	def export_shader(self, name, module, spec_values, resources):
+		from .datafile import Resource, Statement
+		shader_res = Resource(name, "shader")
+
+		st = Statement("module", module)
+		for k, v in spec_values.items():
+			st.sub.append(Statement("specialize", k, v))
+		shader_res.statements.append(st)
+
+		return shader_res
+
 
 class MaterialAtlasExporter:
 	def __init__(self):
diff --git a/blender/io_mspgl/material.py b/blender/io_mspgl/material.py
index 633f030f..fc30d339 100644
--- a/blender/io_mspgl/material.py
+++ b/blender/io_mspgl/material.py
@@ -222,6 +222,7 @@ class Material:
 		self.receive_shadows = material.receive_shadows
 		self.cast_shadows = (material.shadow_method!='NONE')
 		self.blend_type = 'ALPHA' if material.blend_method=='BLEND' else 'NONE'
+		self.alpha_cutoff = material.alpha_threshold if material.blend_method=='CLIP' else 0.0
 		self.image_based_lighting = material.image_based_lighting
 
 		if self.render_mode=='EXTERNAL' and not self.technique:
-- 
2.45.2