From e1d07383b29e8581230b50f45606192d1f21f5dd Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 28 Mar 2021 12:46:33 +0300
Subject: [PATCH] Fix and improve vertex group support

Some parts of the export code had gotten out of sync in 306be12.

Groups and weights now have dedicated attributes instead of using an
arbitrary generic attribute.  They're also separate attributes,
allowing up to four groups per vertex.
---
 blender/io_mspgl/export_mesh.py | 19 +++++++++++--------
 blender/io_mspgl/mesh.py        | 19 +++++++++++++++----
 source/builders/vertexbuilder.h | 24 ++++++++++++++++++++++++
 source/core/vertexarray.cpp     |  8 ++++++++
 source/core/vertexformat.cpp    |  4 ++++
 source/core/vertexformat.h      |  9 ++++++++-
 6 files changed, 70 insertions(+), 13 deletions(-)

diff --git a/blender/io_mspgl/export_mesh.py b/blender/io_mspgl/export_mesh.py
index 0d27a71c..68d93cbc 100644
--- a/blender/io_mspgl/export_mesh.py
+++ b/blender/io_mspgl/export_mesh.py
@@ -77,7 +77,8 @@ class MeshExporter:
 				st.append(Token("TANGENT3"))
 				st.append(Token("BINORMAL3"))
 		if mesh.vertex_groups:
-			st.append(Token("GENERIC{}_0".format(mesh.max_groups_per_vertex*2)))
+			st.append(Token("GROUP{}".format(mesh.max_groups_per_vertex)))
+			st.append(Token("WEIGHT{}".format(mesh.max_groups_per_vertex)))
 		st.append(Token("VERTEX3"))
 
 		normal = None
@@ -86,6 +87,7 @@ class MeshExporter:
 		tan = None
 		bino = None
 		group = None
+		weight = None
 		for v in mesh.vertices:
 			if v.normal!=normal:
 				st.sub.append(Statement("normal", *v.normal))
@@ -108,13 +110,14 @@ class MeshExporter:
 					st.sub.append(Statement("binormal", *v.bino))
 					bino = v.bino
 			if mesh.vertex_groups:
-				group_attr = [(group_index_map[g.group], g.weight*v.group_weight_scale) for g in v.groups[:mesh.max_groups_per_vertex]]
-				while len(group_attr)<mesh.max_groups_per_vertex:
-					group_attr.append((0, 0.0))
-				group_attr = list(itertools.chain(*group_attr))
-				if group_attr!=group:
-					st.sub.append(Statement("generic", 0, *group_attr))
-					group = group_attr
+				v_group = [g.group for g in v.groups]
+				v_weight = [g.weight for g in v.groups]
+				if v_group!=group:
+					st.sub.append(Statement("group", *v_group))
+					group = v_group
+				if v_weight!=weight:
+					st.sub.append(Statement("weight", *v_weight))
+					weight = v_weight
 			st.sub.append(Statement("vertex", *v.co))
 
 		statements.append(st)
diff --git a/blender/io_mspgl/mesh.py b/blender/io_mspgl/mesh.py
index da5e76aa..d9ae6b76 100644
--- a/blender/io_mspgl/mesh.py
+++ b/blender/io_mspgl/mesh.py
@@ -70,8 +70,12 @@ class Vertex:
 
 class VertexGroup:
 	def __init__(self, group):
-		self.group = group.group
-		self.weight = group.weight
+		if group:
+			self.group = group.group
+			self.weight = group.weight
+		else:
+			self.group = 0
+			self.weight = 0.0
 
 
 class Face:
@@ -162,8 +166,9 @@ class Mesh:
 
 		# Clone basic data
 		self.vertices = [Vertex(v) for v in mesh.vertices]
-		for v in self.vertices:
-			v.groups = [VertexGroup(g) for g in v.groups]
+		if self.vertex_groups:
+			for v in self.vertices:
+				v.groups = [VertexGroup(g) for g in v.groups]
 
 		self.faces = [Face(f) for f in mesh.polygons]
 		self.edges = [Edge(e) for e in mesh.edges]
@@ -172,6 +177,7 @@ class Mesh:
 
 		self.use_auto_smooth = mesh.use_auto_smooth
 		self.auto_smooth_angle = mesh.auto_smooth_angle
+		self.max_groups_per_vertex = mesh.max_groups_per_vertex
 
 		# Clone only the desired UV layers
 		if mesh.use_uv=='NONE' or not mesh.uv_layers:
@@ -371,6 +377,9 @@ class Mesh:
 		progress.pop_task()
 
 	def prepare_vertex_groups(self, obj):
+		if not self.vertex_groups:
+			return
+
 		for v in self.vertices:
 			if v.groups:
 				weight_sum = sum(g.weight for g in v.groups)
@@ -378,6 +387,8 @@ class Mesh:
 				weight_scale = weight_sum/sum(g.weight for g in v.groups)
 				for g in v.groups:
 					g.weight *= weight_scale
+			while len(v.groups)<self.max_groups_per_vertex:
+				v.groups.append(VertexGroup(None))
 
 		if obj.parent and obj.parent.type=="ARMATURE":
 			armature = obj.parent.data
diff --git a/source/builders/vertexbuilder.h b/source/builders/vertexbuilder.h
index b5278045..5c297346 100644
--- a/source/builders/vertexbuilder.h
+++ b/source/builders/vertexbuilder.h
@@ -140,6 +140,30 @@ public:
 	void color(const Color &c)
 	{ attrib(get_attribute_semantic(COLOR4_FLOAT), Vector4(c.r, c.g, c.b, c.a)); }
 
+	void group(int g0)
+	{ group(g0, 0, 0, 0); }
+
+	void group(int g0, int g1)
+	{ group(g0, g1, 0, 0); }
+
+	void group(int g0, int g1, int g2)
+	{ group(g0, g1, g2, 0); }
+
+	void group(int g0, int g1, int g2, int g3)
+	{ attrib(get_attribute_semantic(GROUP4), Vector4(g0, g1, g2, g3)); }
+
+	void weight(float w0)
+	{ weight(w0, 0, 0, 0); }
+
+	void weight(float w0, float w1)
+	{ weight(w0, w1, 0, 0); }
+
+	void weight(float w0, float w1, float w2)
+	{ weight(w0, w1, w2, 0); }
+
+	void weight(float w0, float w1, float w2, float w3)
+	{ attrib(get_attribute_semantic(WEIGHT4), Vector4(w0, w1, w2, w3)); }
+
 	void generic(unsigned i, float x)
 	{ generic(i, x, 0, 0, 1); }
 
diff --git a/source/core/vertexarray.cpp b/source/core/vertexarray.cpp
index 712e76e6..67a90ef7 100644
--- a/source/core/vertexarray.cpp
+++ b/source/core/vertexarray.cpp
@@ -76,6 +76,14 @@ VertexArray::Loader::Loader(VertexArray &a):
 	add("generic", static_cast<void (Loader::*)(unsigned, float, float, float, float)>(&Loader::generic));
 	add("tangent", static_cast<void (Loader::*)(float, float, float)>(&Loader::tangent));
 	add("binormal", static_cast<void (Loader::*)(float, float, float)>(&Loader::binormal));
+	add("group", static_cast<void (Loader::*)(int)>(&Loader::group));
+	add("group", static_cast<void (Loader::*)(int, int)>(&Loader::group));
+	add("group", static_cast<void (Loader::*)(int, int, int)>(&Loader::group));
+	add("group", static_cast<void (Loader::*)(int, int, int, int)>(&Loader::group));
+	add("weight", static_cast<void (Loader::*)(float)>(&Loader::weight));
+	add("weight", static_cast<void (Loader::*)(float, float)>(&Loader::weight));
+	add("weight", static_cast<void (Loader::*)(float, float, float)>(&Loader::weight));
+	add("weight", static_cast<void (Loader::*)(float, float, float, float)>(&Loader::weight));
 
 	add("vertex2",   static_cast<void (Loader::*)(float, float)>(&Loader::vertex));
 	add("vertex3",   static_cast<void (Loader::*)(float, float, float)>(&Loader::vertex));
diff --git a/source/core/vertexformat.cpp b/source/core/vertexformat.cpp
index 5d026e2e..2ce02e2e 100644
--- a/source/core/vertexformat.cpp
+++ b/source/core/vertexformat.cpp
@@ -120,6 +120,10 @@ void operator>>(const LexicalConverter &conv, VertexAttribute &a)
 		a = TANGENT3;
 	else if(str=="BINORMAL3")
 		a = BINORMAL3;
+	else if(str.size()==6 && !str.compare(0, 5, "GROUP") && str[5]>='1' && str[5]<='4')
+		a = static_cast<VertexAttribute>(GROUP1+(str[5]-'1'));
+	else if(str.size()==7 && !str.compare(0, 6, "WEIGHT") && str[6]>='1' && str[6]<='4')
+		a = static_cast<VertexAttribute>(WEIGHT1+(str[6]-'1'));
 	else if(str.size()>=9 && !str.compare(0, 8, "TEXCOORD") && str[8]>='1' && str[8]<='4')
 	{
 		if(str.size()==9)
diff --git a/source/core/vertexformat.h b/source/core/vertexformat.h
index 93794c35..0dbde9f9 100644
--- a/source/core/vertexformat.h
+++ b/source/core/vertexformat.h
@@ -27,7 +27,14 @@ enum VertexAttribute
 	NORMAL3 = 18,
 	TANGENT3 = 26,
 	BINORMAL3 = 34,
-	// Attributes 5 and 6 reserved for vertex groups and weights
+	GROUP1 = 40,
+	GROUP2,
+	GROUP3,
+	GROUP4,
+	WEIGHT1 = 48,
+	WEIGHT2,
+	WEIGHT3,
+	WEIGHT4,
 	TEXCOORD1 = 56,
 	TEXCOORD2,
 	TEXCOORD3,
-- 
2.43.0