From fb1a7f1e8b11cd26510edaa59c8e481f689a7b04 Mon Sep 17 00:00:00 2001
From: tangziwen <tzwtangziwen@163.com>
Date: Fri, 22 May 2015 09:07:57 +0800
Subject: [PATCH] fix Terrain::getIntersectionPoint

---
 cocos/3d/CCTerrain.cpp | 51 ++++++++++++++++++++++++++++++++++++++++--
 cocos/3d/CCTerrain.h   |  2 ++
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/cocos/3d/CCTerrain.cpp b/cocos/3d/CCTerrain.cpp
index d8c9b13a4f..6126b625d1 100644
--- a/cocos/3d/CCTerrain.cpp
+++ b/cocos/3d/CCTerrain.cpp
@@ -327,6 +327,10 @@ float Terrain::getHeight(float x, float z, Vec3 * normal)
     if(image_x>=_imageWidth-1 || image_y >=_imageHeight-1 || image_x<0 || image_y<0)
     {
         return 0;
+        if (normal)
+        {
+            normal->setZero();
+        }
     }else
     {
         float a = getImageHeight(i,j)*getScaleY();
@@ -513,12 +517,14 @@ cocos2d::Vec3 Terrain::getIntersectionPoint(const Ray & ray)
     Vec3 lastRayPosition =rayPos;
     rayPos += rayStep; 
     // Linear search - Loop until find a point inside and outside the terrain Vector3 
-    float height = getHeight(rayPos.x,rayPos.z); 
-
+    Vec3 normal;
+    float height = getHeight(rayPos.x, rayPos.z, &normal);
     while (rayPos.y > height)
     {
         lastRayPosition = rayPos; 
         rayPos += rayStep; 
+        if (normal.isZero())
+            return Vec3(0, 0, 0);
         height = getHeight(rayPos.x,rayPos.z); 
     } 
 
@@ -538,6 +544,47 @@ cocos2d::Vec3 Terrain::getIntersectionPoint(const Ray & ray)
     return collisionPoint;
 }
 
+bool Terrain::getIntersectionPoint(const Ray & ray, Vec3 & intersectionPoint)
+{
+    Vec3 dir = ray._direction;
+    dir.normalize();
+    Vec3 rayStep = _terrainData._chunkSize.width*0.25*dir;
+    Vec3 rayPos = ray._origin;
+    Vec3 rayStartPosition = ray._origin;
+    Vec3 lastRayPosition = rayPos;
+    rayPos += rayStep;
+    // Linear search - Loop until find a point inside and outside the terrain Vector3 
+    Vec3 normal;
+    float height = getHeight(rayPos.x, rayPos.z, &normal);
+    while (rayPos.y > height)
+    {
+        lastRayPosition = rayPos;
+        rayPos += rayStep;
+        if (normal.isZero())
+        {
+            intersectionPoint = Vec3(0, 0, 0);
+            return false;
+        }
+        height = getHeight(rayPos.x, rayPos.z);
+    }
+
+    Vec3 startPosition = lastRayPosition;
+    Vec3 endPosition = rayPos;
+
+    for (int i = 0; i < 32; i++)
+    {
+        // Binary search pass 
+        Vec3 middlePoint = (startPosition + endPosition) * 0.5f;
+        if (middlePoint.y < height)
+            endPosition = middlePoint;
+        else
+            startPosition = middlePoint;
+    }
+    Vec3 collisionPoint = (startPosition + endPosition) * 0.5f;
+    intersectionPoint = collisionPoint;
+    return true;
+}
+
 void Terrain::setMaxDetailMapAmount(int max_value)
 {
     _maxDetailMapValue = max_value;
diff --git a/cocos/3d/CCTerrain.h b/cocos/3d/CCTerrain.h
index c348ecb22b..4a78781b19 100644
--- a/cocos/3d/CCTerrain.h
+++ b/cocos/3d/CCTerrain.h
@@ -343,6 +343,8 @@ public:
      */
     Vec3 getIntersectionPoint(const Ray & ray);
 
+    bool getIntersectionPoint(const Ray & ray, Vec3 & intersectionPoint);
+
     /**
      * set the MaxDetailAmount.
      */