From ab59f5a9e66b3fc7872ad96ec7949940189f0819 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 3 Sep 2012 22:06:25 +0300
Subject: [PATCH] Fix vertex array offsets

Since array application order may now be different from the format order,
and VertexArrayBuilder stores components in the latter, calculating the
offsets while applying arrays gives wrong results.
---
 source/vertexarray.cpp | 36 ++++++++++++++++++++++--------------
 source/vertexarray.h   | 10 +++++++++-
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/source/vertexarray.cpp b/source/vertexarray.cpp
index d834ab7c..6c0e5f1a 100644
--- a/source/vertexarray.cpp
+++ b/source/vertexarray.cpp
@@ -28,12 +28,18 @@ void VertexArray::reset(const VertexFormat &f)
 
 	arrays.clear();
 
+	unsigned offset = 0;
 	for(const unsigned char *c=format.begin(); c!=format.end(); ++c)
 	{
 		unsigned slot = get_array_slot(*c);
 		if(slot>=arrays.size())
 			arrays.resize(slot+1);
-		arrays[slot] = *c;
+
+		Array &arr = arrays[slot];
+		arr.component = *c;
+		arr.offset = offset;
+
+		offset += get_component_size(*c);
 	}
 }
 
@@ -133,7 +139,6 @@ void VertexArray::apply() const
 	}
 
 	const float *base = (vbuf ? 0 : &data[0]);
-	unsigned offset = 0;
 	unsigned stride_bytes = stride*sizeof(float);
 	unsigned active_tex = 0;
 	unsigned n_arrays = arrays.size();
@@ -141,25 +146,25 @@ void VertexArray::apply() const
 		n_arrays = max(n_arrays, old->arrays.size());
 	for(unsigned i=0; i<n_arrays; ++i)
 	{
-		unsigned char arr = (i<arrays.size() ? arrays[i] : 0);
-		unsigned char old_arr = (old && i<old->arrays.size() ? old->arrays[i] : 0);
+		const Array *arr = ((i<arrays.size() && arrays[i].component) ? &arrays[i] : 0);
+		const Array *old_arr = ((old && i<old->arrays.size() && old->arrays[i].component) ? &old->arrays[i] : 0);
 		if(!arr && !old_arr)
 			continue;
 
-		unsigned char comp = (arr ? arr : old_arr);
+		unsigned char comp = (arr ? arr->component : old_arr->component);
 		unsigned sz = get_component_size(comp);
 		unsigned t = get_component_type(comp);
 		GLenum array_type = 0;
 		if(t==get_component_type(VERTEX3))
 		{
 			if(arr)
-				glVertexPointer(sz, GL_FLOAT, stride_bytes, base+offset);
+				glVertexPointer(sz, GL_FLOAT, stride_bytes, base+arr->offset);
 			array_type = GL_VERTEX_ARRAY;
 		}
 		else if(t==get_component_type(NORMAL3))
 		{
 			if(arr)
-				glNormalPointer(GL_FLOAT, stride_bytes, base+offset);
+				glNormalPointer(GL_FLOAT, stride_bytes, base+arr->offset);
 			array_type = GL_NORMAL_ARRAY;
 		}
 		else if(t==get_component_type(COLOR4_FLOAT))
@@ -167,9 +172,9 @@ void VertexArray::apply() const
 			if(arr)
 			{
 				if(sz==1)
-					glColorPointer(4, GL_UNSIGNED_BYTE, stride_bytes, base+offset);
+					glColorPointer(4, GL_UNSIGNED_BYTE, stride_bytes, base+arr->offset);
 				else
-					glColorPointer(sz, GL_FLOAT, stride_bytes, base+offset);
+					glColorPointer(sz, GL_FLOAT, stride_bytes, base+arr->offset);
 			}
 			array_type = GL_COLOR_ARRAY;
 		}
@@ -182,7 +187,7 @@ void VertexArray::apply() const
 				active_tex = t;
 			}
 			if(arr)
-				glTexCoordPointer(sz, GL_FLOAT, stride_bytes, base+offset);
+				glTexCoordPointer(sz, GL_FLOAT, stride_bytes, base+arr->offset);
 			array_type = GL_TEXTURE_COORD_ARRAY;
 		}
 		else
@@ -190,7 +195,7 @@ void VertexArray::apply() const
 			if(t>=get_component_type(ATTRIB1))
 				t -= get_component_type(ATTRIB1);
 			if(arr)
-				glVertexAttribPointer(t, sz, GL_FLOAT, false, stride_bytes, base+offset);
+				glVertexAttribPointer(t, sz, GL_FLOAT, false, stride_bytes, base+arr->offset);
 		}
 
 		// Only change enable state if needed
@@ -208,9 +213,6 @@ void VertexArray::apply() const
 			else
 				glDisableVertexAttribArray(t);
 		}
-
-		if(arr)
-			offset += sz;
 	}
 
 	if(active_tex)
@@ -221,6 +223,12 @@ void VertexArray::apply() const
 }
 
 
+VertexArray::Array::Array():
+	component(0),
+	offset(0)
+{ }
+
+
 VertexArray::Loader::Loader(VertexArray &a):
 	VertexArrayBuilder(a)
 {
diff --git a/source/vertexarray.h b/source/vertexarray.h
index 26204b31..1887ad91 100644
--- a/source/vertexarray.h
+++ b/source/vertexarray.h
@@ -26,10 +26,18 @@ public:
 	};
 
 private:
+	struct Array
+	{
+		unsigned char component;
+		unsigned char offset;
+
+		Array();
+	};
+
 	VertexFormat format;
 	std::vector<float> data;
 	unsigned stride;
-	std::vector<unsigned char> arrays;
+	std::vector<Array> arrays;
 	RefPtr<Buffer> vbuf;
 	bool defer_vbuf;
 	mutable bool dirty;
-- 
2.43.0