From a30ae7d0fb13b9a00a17e621463c186fb6ac5ada Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <matthias@gamezock.de>
Date: Wed, 6 Jan 2010 06:12:58 +0100
Subject: Optimized triangle normal handling

---
 src/Collision.cpp |  2 +-
 src/Level.cpp     | 18 +++++++-----------
 src/MathUtil.h    |  2 +-
 src/Renderer.cpp  |  2 +-
 src/Triangle.h    | 33 ++++++++++++++++++++++-----------
 5 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/src/Collision.cpp b/src/Collision.cpp
index 21ef083..81bc89d 100644
--- a/src/Collision.cpp
+++ b/src/Collision.cpp
@@ -136,7 +136,7 @@ bool Collision::test(const Triangle &t, const vmml::vec3f &m, float r, const vmm
 
   float d;
 
-  vmml::vec3f triangleNormal = t.computeNormal();
+  vmml::vec3f triangleNormal = t.getNormal();
   if(test(t, MathUtil::Ray(m - r*triangleNormal, move), &d) && d > -MathUtil::EPSILON) {
     if(d < 1) {
       if(distance)
diff --git a/src/Level.cpp b/src/Level.cpp
index 9b2aa78..c6ba915 100644
--- a/src/Level.cpp
+++ b/src/Level.cpp
@@ -172,13 +172,13 @@ TriangleRecord Level::loadWall(xmlNodePtr wallNode) {
       if(++vertexNum > 2)
         break;
 
-      wall.getTriangle().setVertex(vertexNum, loadVector(node));
+      wall.getTriangle().setVertex(vertexNum, loadVector(node), false);
     }
     else if(!xmlStrcmp(node->name, (xmlChar*)"normal")) {
       if(vertexNum < 0)
         continue;
 
-      wall.getTriangle().setNormal(vertexNum, loadVector(node));
+      wall.getTriangle().setVertexNormal(vertexNum, loadVector(node));
     }
     else if(!xmlStrcmp(node->name, (xmlChar*)"texcoords")) {
       if(vertexNum < 0) continue;
@@ -197,18 +197,14 @@ TriangleRecord Level::loadWall(xmlNodePtr wallNode) {
     }
   }
 
-  vmml::vec3f normal = wall.getTriangle().computeNormal();
+  wall.getTriangle().updateNormal();
+  vmml::vec3f normal = wall.getTriangle().getNormal();
 
-  if(normal.squared_length() > 0) {
-    normal.normalize();
-
-    for(int i = 0; i < 3; ++i) {
-      if(wall.getTriangle().getNormal(i).squared_length() == 0)
-        wall.getTriangle().setNormal(i, normal);
-    }
+  for(int i = 0; i < 3; ++i) {
+    if(wall.getTriangle().getVertexNormal(i).squared_length() == 0)
+      wall.getTriangle().setVertexNormal(i, normal);
   }
 
-
   return wall;
 }
 
diff --git a/src/MathUtil.h b/src/MathUtil.h
index 3f7ba90..639336a 100644
--- a/src/MathUtil.h
+++ b/src/MathUtil.h
@@ -51,7 +51,7 @@ class MathUtil {
     class Plane {
       public:
         Plane(const vmml::vec3f &n = vmml::vec3f::ZERO, float d0 = 0) : normal(n), d(d0) {}
-        Plane(const Triangle &t) : normal(t.computeNormal()), d(t.getVertex(0).dot(normal)) {}
+        Plane(const Triangle &t) : normal(t.getNormal()), d(t.getVertex(0).dot(normal)) {}
 
         bool contains(const vmml::vec3f &v) const {
           return (fabsf(normal.dot(v) - d) < EPSILON);
diff --git a/src/Renderer.cpp b/src/Renderer.cpp
index 5d86565..512883d 100644
--- a/src/Renderer.cpp
+++ b/src/Renderer.cpp
@@ -53,7 +53,7 @@ void Renderer::renderTriangle(const Triangle &t) {
 
   for(int i = 0; i < 3; ++i) {
     glTexCoord2fv(t.getTexCoords(i).array);
-    glNormal3fv(t.getNormal(i).array);
+    glNormal3fv(t.getVertexNormal(i).array);
     glVertex3fv(t.getVertex(i).array);
   }
 }
diff --git a/src/Triangle.h b/src/Triangle.h
index 2b34c3f..e13574c 100644
--- a/src/Triangle.h
+++ b/src/Triangle.h
@@ -30,30 +30,44 @@ class Triangle {
     Triangle() : color(vmml::vec4f::ONE), texture(0) {
       vertices[0] = vertices[1] = vertices[2] = vmml::vec3f::ZERO;
       normals[0] = normals[1] = normals[2] = vmml::vec3f::ZERO;
+      normal = vmml::vec3f::ZERO;
       texcoords[0] = texcoords[1] = texcoords[2] = vmml::vec2f::ZERO;
     }
 
-    Triangle(const vmml::vec3f &v1, const vmml::vec3f &v2, const vmml::vec3f &v3, const vmml::vec4f &color0) : color(color0), texture(0) {
+    Triangle(const vmml::vec3f &v1, const vmml::vec3f &v2, const vmml::vec3f &v3, const vmml::vec4f &color0, bool update = true) : color(color0), texture(0) {
       vertices[0] = v1;
       vertices[1] = v2;
       vertices[2] = v3;
 
       normals[0] = normals[1] = normals[2] = vmml::vec3f::ZERO;
       texcoords[0] = texcoords[1] = texcoords[2] = vmml::vec2f::ZERO;
+
+      if(update)
+        updateNormal();
+      else
+        normal = vmml::vec3f::ZERO;
     }
     
     const vmml::vec3f& getVertex(int i) const {return vertices[i];}
-    vmml::vec3f& getVertex(int i) {return vertices[i];}
-    void setVertex(int i, vmml::vec3f v) {
+    void setVertex(int i, vmml::vec3f v, bool update = true) {
       vertices[i] = v;
+
+      if(update)
+        updateNormal();
+    }
+
+    void updateNormal() {
+      normal = vertices[0].compute_normal(vertices[1], vertices[2]);
     }
 
-    const vmml::vec3f& getNormal(int i) const {return normals[i];}
-    vmml::vec3f& getNormal(int i) {return normals[i];}
-    void setNormal(int i, vmml::vec3f n) {
+    const vmml::vec3f& getVertexNormal(int i) const {return normals[i];}
+    vmml::vec3f& getVertexNormal(int i) {return normals[i];}
+    void setVertexNormal(int i, vmml::vec3f n) {
       normals[i] = n;
     }
 
+    const vmml::vec3f& getNormal() const {return normal;}
+
     const vmml::vec2f& getTexCoords(int i) const {return texcoords[i];}
     vmml::vec2f& getTexCoords(int i) {return texcoords[i];}
     void setTexCoords(int i, vmml::vec2f t) {
@@ -73,12 +87,8 @@ class Triangle {
       color = c;
     }
     
-    vmml::vec3f computeNormal() const {
-      return vertices[0].compute_normal(vertices[1], vertices[2]);
-    }
-    
     bool isDegenerate() const {
-      return (computeNormal().squared_length() == 0);
+      return (normal.squared_length() == 0);
     }
 
     void transform(const vmml::mat4f &matrix) {
@@ -94,6 +104,7 @@ class Triangle {
   private:
     vmml::vec3f vertices[3];
     vmml::vec3f normals[3];
+    vmml::vec3f normal;
     vmml::vec2f texcoords[3];
     vmml::vec4f color;
     unsigned texture;
-- 
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