From 772631d07bced1963b54978c7eb86ebfd69f633c Mon Sep 17 00:00:00 2001
From: Stijn Buys <ingar@osirion.org>
Date: Fri, 26 Nov 2010 19:02:27 +0000
Subject: Brute-force patch subdivision

---
 src/math/functions.h |  9 +++++++++
 src/model/mapfile.cc | 51 +++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 48 insertions(+), 12 deletions(-)

diff --git a/src/math/functions.h b/src/math/functions.h
index 8135392..27a068e 100644
--- a/src/math/functions.h
+++ b/src/math/functions.h
@@ -107,6 +107,15 @@ inline void swap(float &x, float &y)
 	y = tmp;
 }
 
+/// float to the n-th power
+inline float pow(const float x, const size_t pow) {
+	float r = 1;
+	for (size_t i = 1; i <= pow; i++) {
+		r *= x;
+	}
+	return r;
+}
+
 } // namespace math
 
 #endif // __INCLUDED_MATH_FUNCTIONS_H__
diff --git a/src/model/mapfile.cc b/src/model/mapfile.cc
index f57106d..76a75a9 100644
--- a/src/model/mapfile.cc
+++ b/src/model/mapfile.cc
@@ -388,18 +388,45 @@ bool MapFile::read_patchdef()
 	}
 	
 	// load patch data into the model geometry
-	// TODO triangulate, assign texture coordinates
-	for (size_t r = 0; r < rows-1; r++) {
-		for (size_t c = 0; c < columns -1; c++) {
-			// unwind face counter-clockwise
-			Quad *quad = new Quad(
-				patchvertices[r+1][c+1],
-				patchvertices[r][c+1],
-				patchvertices[r][c],
-				patchvertices[r+1][c],
-				math::normal(patchvertices[r][c+1], patchvertices[r][c], patchvertices[r+1][c+1])
-			);
-			primitives->add_quad(quad);
+	// the patch is a set of quadratic B-splines with m = n =2
+	// TODO texture coordinates, normals
+	
+	// TODO variable sibdivision
+	const size_t subdivide = 4;
+	const float binom[3] = {1, 2, 1};
+	
+	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];
+			
+			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;
+					
+					for (size_t mi = 0; mi < 3; mi++) {
+						for (size_t mj = 0; mj < 3; mj++) {
+							mesh[i][j] +=
+								patchvertices[r+mi][c+mj] * 
+								binom[mi] * pow (u,mi) * pow(1.0f - u, 2-mi) * 
+								binom[mj] * pow (v,mj) * pow(1.0f - v, 2-mj);
+						}
+					}
+				}
+			}
+				
+			for (size_t i = 0; i < subdivide; i++) {
+				for (size_t j = 0; j < subdivide; j++) {
+					Quad *quad = new Quad(
+							mesh[i+1][j+1],
+							mesh[i][j+1],
+							mesh[i][j],
+							mesh[i+1][j],
+							math::normal(mesh[i][j+1], mesh[i][j], mesh[i+1][j+1])
+					);
+					primitives->add_quad(quad);
+				}
+			}
 		}
 	}
 
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