From 5c949b7e6eaf0076199f803f83e37290f0c549a8 Mon Sep 17 00:00:00 2001
From: Stijn Buys <ingar@osirion.org>
Date: Thu, 2 Dec 2010 13:07:57 +0000
Subject: Improved patch mesh subdivision.

---
 src/model/mapfile.cc | 53 ++++++++++++++++++++++++++++++++++++++--------------
 src/model/mapfile.h  |  8 ++++++++
 2 files changed, 47 insertions(+), 14 deletions(-)

(limited to 'src/model')

diff --git a/src/model/mapfile.cc b/src/model/mapfile.cc
index 7775c8d..c016659 100644
--- a/src/model/mapfile.cc
+++ b/src/model/mapfile.cc
@@ -396,21 +396,46 @@ bool MapFile::read_patchdef()
 	// patchvertices[][] are the control points as read from the .map file
 	// mesh[][] is a subdivideXsubdivide quad mesh calculated for each set of 9 control points in the patch
 	
-	// TODO variable sibdivision
-	const size_t subdivide = 4;
+	// binomial coefficient
 	const float binom[3] = {1.0f, 2.0f, 1.0f};
-	
+	size_t subdivide_u = 0;
+	size_t subdivide_v = 0;
+		
 	for (size_t r = 0; r < rows-2; r +=2 ) {
 		for (size_t c = 0; c < columns -2; c += 2) {
 			
-			math::Vector3f mesh[subdivide + 1][subdivide +1];
-			math::Vector3f meshnormals[subdivide + 1][subdivide +1];
-			math::Vector2f meshtexcoords[subdivide + 1][subdivide +1];
-
-			for (size_t i = 0; i <= subdivide; i++) {
-				const float u = (float) i / (float) subdivide;
-				for (size_t j = 0; j <= subdivide; j++) {
-					const float v = (float) j / (float) subdivide;
+			// if columns are collinear, do not subdivide in u direction
+			if (
+				collinear(patchvertices[r][c], patchvertices[r+1][c], patchvertices[r+2][c]) &&
+				collinear(patchvertices[r][c+1], patchvertices[r+1][c+1], patchvertices[r+2][c+1]) &&
+				collinear(patchvertices[r][c+2], patchvertices[r+1][c+2], patchvertices[r+2][c+2])
+			) {
+				subdivide_u = 1;
+			} else {
+				subdivide_u = 4;
+			}
+			
+			
+			// if rows are collinear, do not subdivide in v direction
+			if (
+				collinear(patchvertices[r][c], patchvertices[r][c+1], patchvertices[r][c+2]) &&
+				collinear(patchvertices[r+1][c], patchvertices[r+1][c+1], patchvertices[r+1][c+2]) &&
+				collinear(patchvertices[r+2][c], patchvertices[r+2][c+1], patchvertices[r+2][c+2])
+			) {
+				subdivide_v = 1;
+			} else {
+				subdivide_v = 4;
+			}
+
+			math::Vector3f mesh[subdivide_u + 1][subdivide_v +1];
+			math::Vector3f meshnormals[subdivide_u + 1][subdivide_v +1];
+			math::Vector2f meshtexcoords[subdivide_u + 1][subdivide_v +1];
+
+			for (size_t i = 0; i <= subdivide_u; i++) {
+				const float u = (float) i / (float) subdivide_u;
+				
+				for (size_t j = 0; j <= subdivide_v; j++) {
+					const float v = (float) j / (float) subdivide_v;
 					math::Vector3f tan_u;
 					math::Vector3f tan_v;
 					
@@ -418,7 +443,7 @@ bool MapFile::read_patchdef()
 					// we cheat and pull the edge points towards the middle
 					float un = u;
 					float vn = v;
-					if ((i ==0) || (j==0) || (i == subdivide) || (j == subdivide)) {
+					if ((i ==0) || (j==0) || (i == subdivide_u) || (j == subdivide_v)) {
 						un = (u - 0.5f) * 0.95f + 0.5f;
 						vn = (v - 0.5f) * 0.95f + 0.5f;
 					}
@@ -480,8 +505,8 @@ bool MapFile::read_patchdef()
 			}
 			
 			const math::Vector3f zero;
-			for (size_t i = 0; i < subdivide; i++) {
-				for (size_t j = 0; j < subdivide; j++) {
+			for (size_t i = 0; i < subdivide_u; i++) {
+				for (size_t j = 0; j < subdivide_v; j++) {
 					Quad *quad = new Quad(
 							mesh[i+1][j+1] * SCALE,
 							mesh[i][j+1] * SCALE,
diff --git a/src/model/mapfile.h b/src/model/mapfile.h
index a12e295..c78b56c 100644
--- a/src/model/mapfile.h
+++ b/src/model/mapfile.h
@@ -128,6 +128,14 @@ private:
 	inline const math::BoundingBox3f & box() const {
 		return map_box;
 	}
+	
+	inline bool collinear(const math::Vector3f & a, const math::Vector3f & b, const math::Vector3f & c)
+	{
+		if ((distance(a, b) + distance(b, c)) == distance(a, c))
+			return true;
+		else
+			return false;
+	}
 
 	/// close the file
 	void close();
-- 
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