Conform Player to Terrain

Here is a little bit of code that we added to the engine to make the player conform to the terrain. It was originally written to work with the tank model seen at the bottom of this gallery image: www.garagegames.com/mg/snapshot/view.php?qid=302

Have fun, and let us know if you find any interesting ways to use it.

To get your player to confrom to the terrain, in player.cc:

At the bottom of PlayerData::PlayerData() add:

conformToGround = false;
   smoothCamera = 0.0f;

At the bottom of PlayerData::initPersistFields() add:

addField("conformToGround", TypeBool, Offset(conformToGround, PlayerData));
   addField("smoothCamera", TypeF32, Offset(smoothCamera,PlayerData));

At the bottom of PlayerData::packData(BitStream* stream) add:

stream->write(conformToGround);
   stream->write(smoothCamera);

At the bottom of PlayerData::unpackData(BitStream* stream) add:

stream->read(&conformToGround);
   stream->read(&smoothCamera);

To Player::setPosition(const Point3F& pos,const Point3F& rot) add the following code to the end of the "else" clause:

if (mDataBlock && mDataBlock->conformToGround)
      {
         RayInfo surfaceInfo;
         Point3F above = Point3F(pos.x,pos.y,pos.z + 0.5f);
         Point3F below = Point3F(pos.x,pos.y,pos.z - 100.0f);
         if (gClientContainer.castRay(above,below,TerrainObjectType | InteriorObjectType,&surfaceInfo))
         {
            Point3F x,y,z;
            z = surfaceInfo.normal;
            z.normalize();
            mat.getColumn(1,&y);
            mCross(y,z,&x);
            x.normalize();
            mCross(z,x,&y);
            mat.setColumn(0,x);
            mat.setColumn(1,y);
            mat.setColumn(2,z);
         }
      }

To Player::setRenderPosition(const Point3F& pos, const Point3F& rot, F32 dt) add the following code to the end of the outer else clause:

if (mDataBlock && mDataBlock->conformToGround)
      {
         RayInfo surfaceInfo;
         Point3F above = Point3F(pos.x,pos.y,pos.z + 0.5f);
         Point3F below = Point3F(pos.x,pos.y,pos.z - 100.0f);
         if (gClientContainer.castRay(above,below,TerrainObjectType | InteriorObjectType,&surfaceInfo))
         {
            Point3F x,y,z;
            z = surfaceInfo.normal;
            z.normalize();
            mat.getColumn(1,&y);
            mCross(y,z,&x);
            x.normalize();
            mCross(z,x,&y);
            mat.setColumn(0,x);
            mat.setColumn(1,y);
            mat.setColumn(2,z);
         }
      }

In Player::setRenderPosition(const Point3F& pos, const Point3F& rot, F32 dt) change:

Parent::setRenderTransform(mat);
to
[code]
   setRenderTransform(mat);

Add the following method to player.cc:

void Player::setRenderTransform(const MatrixF & mat)
{
   if (mDataBlock && mDataBlock->smoothCamera>0.0001f)
   {
      Point3F pos, x,y,z;
      mat.getColumn(3,&pos);

      // keep compass direction (assume not looking straight up)
      mat.getColumn(1,&y);
      y.z = 0;
      y.normalize();

      // smooth out camera
      MatrixF mat2 = getRenderTransform();
      QuatF q1(mat);
      QuatF q2(mat2);
      F32 k = mDataBlock->smoothCamera;

      q2.x = q2.x * k + (1.0f-k) * q1.x;
      q2.y = q2.y * k + (1.0f-k) * q1.y;
      q2.z = q2.z * k + (1.0f-k) * q1.z;
      q2.w = q2.w * k + (1.0f-k) * q1.w;
      q2.normalize();
      q2.setMatrix(&mat2);
      mat2.setColumn(3,pos);

      // keep up-vector, refigure y & z based on saved off y
      mat2.getColumn(2,&z);
      mCross(y,z,&x);
      x.normalize();
      mCross(z,x,&y);
      mat2.setColumn(0,x);
      mat2.setColumn(1,y);

      Parent::setRenderTransform(mat2);
   }
   else
      Parent::setRenderTransform(mat);
}

In player.h add the following lines to the bottom of the PlayerData struct:

bool conformToGround;
   F32 smoothCamera;

In player.h just after the line:
[code]
   void setPosition(const Point3F& pos,const Point3F& viewRot);

add the following line:

void setRenderTransform(const MatrixF &);

Now you can add the following two fields to the player datablock:

conformToGround = 1; // or 0 by default
smoothCamera = 0.95; // or 0 by default -- 0 is no smoothing, 1 is so smooth the camera won't rotate...