Added support for bevelled collision shapes using

a convex hull collision shape. Disabled by default,
set bevel-factor in stk-config (e.g. to 0.3 0.3 0.3).


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@10466 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/stk_config.xml

@@ -291,9 +291,17 @@
            problem that the amount of push a hit kart receives depends on
            the orientation - if a kart is pushed in the direction it is 
            driving, it will be more (no friction from tires), while when 
-           pushed to the side, hardly anything happens.  -->
-    <collision impulse="300" impulse-time="0.2" side-impulse="900"
-               restitution="0.5"/>
+           pushed to the side, hardly anything happens. 
+         bevel-factor: the X and Y coordinate of each point of the kart
+           chassis (box) are multiplied with (1-bevelX) and (1-bevelY),
+           and the Z coordinate is multiplied with (1+bevelZ). The 
+           resulting point is then added to the chassis collision shape.
+           This gives a bevelled box shape. A value of 0 for all bevel
+           coordinates disables bevelling, and uses a simple box shape.
+           As an example, a value of 1 for x and z will result in a 
+           sharp 'arrow' like shape.  -->
+    <collision impulse="150" impulse-time="0.1" side-impulse="600"
+               restitution="1.0" bevel-factor="0 0 0" />
 
     <!-- Kart-specific plunger and rubber band handling: max-length is
          the maximum length of rubber band before it snaps. force is

src/karts/kart.cpp

@@ -242,10 +242,43 @@ void Kart::createPhysics()
     {
         kart_height = kart_length*0.6f;
     }
-    
-    btBoxShape *shape = new btBoxShape(btVector3(0.5f*kart_width,
-                                                 0.5f*kart_height,
-                                                 0.5f*kart_length));
+
+    btCollisionShape *shape;
+    const Vec3 &bevel = m_kart_properties->getBevelFactor();
+    if(bevel.getX() || bevel.getY() || bevel.getZ())
+    {
+        Vec3 bevel_factor(1.0f-bevel.getX(),
+                          1.0f-bevel.getY(),
+                          1.0f+bevel.getZ() );
+        btConvexHullShape *hull = new btConvexHullShape();
+        for(int x=-1; x<=1; x+=2)
+        {
+            for(int y=-1; y<=1; y+=2)
+            {
+                for(int z=-1; z<=1; z+=2)
+                {
+                    btVector3 p(x*getKartModel()->getWidth() *0.5f,
+                                y*getKartModel()->getHeight()*0.5f,
+                                z*getKartModel()->getLength()*0.5f);
+
+                    hull->addPoint(p);
+                    p *= bevel_factor;
+                    hull->addPoint(p);
+                }   // for z
+            }   // for y
+        }   // for x
+
+        // This especially enables proper drawing of the point cloud
+        hull->initializePolyhedralFeatures();
+        shape = hull;
+    }   // bevel.getX()!=0
+    else
+    {
+        shape = new btBoxShape(btVector3(0.5f*kart_width,
+                                         0.5f*kart_height,
+                                         0.5f*kart_length));
+    }
+
     btTransform shiftCenterOfGravity;
     shiftCenterOfGravity.setIdentity();
     // Shift center of gravity downwards, so that the kart

src/karts/kart_properties.cpp

@@ -98,6 +98,7 @@ KartProperties::KartProperties(const std::string &filename)
         m_squash_duration = m_downward_impulse_factor = UNDEFINED;
 
     m_gravity_center_shift   = Vec3(UNDEFINED);
+    m_bevel_factor           = Vec3(UNDEFINED);
     m_exp_spring_response    = false;
     m_has_skidmarks          = true;
     m_version                = 0;
@@ -432,6 +433,7 @@ void KartProperties::getAllData(const XMLNode * root)
         collision_node->get("impulse-time",  &m_collision_impulse_time);
         collision_node->get("side-impulse",  &m_collision_side_impulse);
         collision_node->get("restitution",   &m_restitution           );
+        collision_node->get("bevel-factor",  &m_bevel_factor          );
     }
 
     //TODO: wheel front right and wheel front left is not loaded, yet is listed as an attribute in the xml file after wheel-radius
@@ -600,6 +602,9 @@ void KartProperties::checkAllSet(const std::string &filename)
     CHECK_NEG(m_collision_impulse_time,     "collision impulse-time"        );
     CHECK_NEG(m_restitution,                "collision restitution"         );
     CHECK_NEG(m_collision_side_impulse,     "collision side-impulse"        );
+    CHECK_NEG(m_bevel_factor.getX(),        "collision bevel-factor"        );
+    CHECK_NEG(m_bevel_factor.getY(),        "collision bevel-factor"        );
+    CHECK_NEG(m_bevel_factor.getZ(),        "collision bevel-factor"        );
     CHECK_NEG(m_upright_tolerance,          "upright tolerance"             );
     CHECK_NEG(m_upright_max_force,          "upright max-force"             );
     CHECK_NEG(m_plunger_in_face_duration[0],"plunger in-face-time[0]"       );

src/karts/kart_properties.hpp

@@ -125,7 +125,9 @@ private:
     /** Increase of turn angle with speed. */
     std::vector<float> m_speed_angle_increase;
 
-
+    /** If != 0 a bevelled box shape is used by using a point cloud as a 
+     *  collision shape. */
+    Vec3  m_bevel_factor;
 
     /** Time a kart is moved upwards after when it is rescued. */
     float m_rescue_time;
@@ -181,7 +183,7 @@ private:
     float       m_wheel_base;
     /** Nitro power boost. */
     float       m_nitro_power_boost;
-    /**< Nitro consumption. */
+    /** Nitro consumption. */
     float       m_nitro_consumption;
     /** Nitro amount for small bottle. */
     float       m_nitro_small_container;
@@ -693,6 +695,9 @@ public:
     float getSquashSlowdown() const {return m_squash_slowdown; }
 
 	bool hasRandomWheels() const { return m_has_rand_wheels; }
+
+    /** Returns the bevel factor (!=0 indicates to use a bevelled box). */
+    const Vec3 &getBevelFactor() const { return m_bevel_factor; }
 };   // KartProperties
 
 #endif