ddnet/src/game/collision.cpp

// copyright (c) 2007 magnus auvinen, see licence.txt for more info
#include <base/system.h>
#include <base/math.h>
#include <base/vmath.h>

#include <math.h>
#include <engine/map.h>
#include <engine/kernel.h>

#include <game/mapitems.h>
#include <game/layers.h>
#include <game/collision.h>

CCollision::CCollision()
{
	m_pTiles = 0;
	m_Width = 0;
	m_Height = 0;
	m_pLayers = 0;
	m_pTele = 0;
	m_pSpeedup = 0;
	m_pFront = 0;
	m_pSwitch = 0;
	m_pDoor = 0;
}

void CCollision::Dest()
{
	if(m_pDoor)
		delete[] m_pDoor;
	m_pTiles = 0;
	m_Width = 0;
	m_Height = 0;
	m_pLayers = 0;
	m_pTele = 0;
	m_pSpeedup = 0;
	m_pFront = 0;
	m_pSwitch = 0;
	m_pDoor = 0;
}

void CCollision::Init(class CLayers *pLayers)
{
	m_pLayers = pLayers;
	m_Width = m_pLayers->GameLayer()->m_Width;
	m_Height = m_pLayers->GameLayer()->m_Height;
	m_pTiles = static_cast<CTile *>(m_pLayers->Map()->GetData(m_pLayers->GameLayer()->m_Data));
	if(m_pLayers->TeleLayer())
		m_pTele = static_cast<CTeleTile *>(m_pLayers->Map()->GetData(m_pLayers->TeleLayer()->m_Tele));
	if(m_pLayers->SpeedupLayer())
		m_pSpeedup = static_cast<CSpeedupTile *>(m_pLayers->Map()->GetData(m_pLayers->SpeedupLayer()->m_Speedup));
	if(m_pLayers->SwitchLayer())
	{
		m_pSwitch = static_cast<CTeleTile *>(m_pLayers->Map()->GetData(m_pLayers->SwitchLayer()->m_Switch));
		m_pDoor = new CDoorTile[m_Width*m_Height];
	}
	else
		m_pDoor = 0;
	if(m_pLayers->FrontLayer())
	{
		m_pFront = static_cast<CTile *>(m_pLayers->Map()->GetData(m_pLayers->FrontLayer()->m_Front));
		for(int i = 0; i < m_Width*m_Height; i++)
			{
				int Index = m_pFront[i].m_Index;
				if(Index > TILE_NPH)
					continue;

				switch(Index)
				{
				case TILE_DEATH:
					m_pFront[i].m_Index = COLFLAG_DEATH;
					break;
				case TILE_SOLID:
					m_pFront[i].m_Index = 0;
					break;
				case TILE_NOHOOK:
					m_pFront[i].m_Index = 0;
					break;
				case TILE_NOLASER:
					m_pFront[i].m_Index = COLFLAG_NOLASER;
					break;
				default:
					m_pFront[i].m_Index = 0;
				}

				// DDRace tiles
				if(Index == TILE_THROUGH || (Index >= TILE_FREEZE && Index <= TILE_UNFREEZE) || (Index >= TILE_TELEIN && Index<=TILE_BOOST) || (Index >= TILE_BEGIN && Index <= TILE_STOPA) || Index == TILE_CP || Index == TILE_CP_F || (Index >= TILE_NPC && Index <= TILE_NPH))
					m_pFront[i].m_Index = Index;
			}
	}

	for(int i = 0; i < m_Width*m_Height; i++)
	{
		int Index = m_pTiles[i].m_Index;
		if(Index > TILE_NPH)
			continue;

		switch(Index)
		{
		case TILE_DEATH:
			m_pTiles[i].m_Index = COLFLAG_DEATH;
			break;
		case TILE_SOLID:
			m_pTiles[i].m_Index = COLFLAG_SOLID;
			break;
		case TILE_NOHOOK:
			m_pTiles[i].m_Index = COLFLAG_SOLID|COLFLAG_NOHOOK;
			break;
		case TILE_NOLASER:
			m_pTiles[i].m_Index = COLFLAG_NOLASER;
			break;
		default:
			m_pTiles[i].m_Index = 0;
		}

		// DDRace tiles
		if(Index == TILE_THROUGH || (Index >= TILE_FREEZE && Index <= TILE_UNFREEZE) || (Index >= TILE_TELEIN && Index<=TILE_BOOST) || (Index >= TILE_BEGIN && Index <= TILE_STOPA) || Index == TILE_CP || Index == TILE_CP_F || (Index >= TILE_NPC && Index <= TILE_NPH))
			m_pTiles[i].m_Index = Index;
	}
}


int CCollision::GetPureMapIndex(vec2 Pos)
{
	int nx = clamp((int)Pos.x/32, 0, m_Width-1);
	int ny = clamp((int)Pos.y/32, 0, m_Height-1);
	return ny*m_Width+nx;
}

std::list<int> CCollision::GetMapIndices(vec2 PrevPos, vec2 Pos, unsigned MaxIndices)
{
	std::list< int > Indices;
	float d = distance(PrevPos, Pos);
	int End(d+1);
	if(!d)
	{
		int nx = clamp((int)Pos.x/32, 0, m_Width-1);
		int ny = clamp((int)Pos.y/32, 0, m_Height-1);
		/*if (m_pTele && (m_pTele[ny*m_Width+nx].m_Type == TILE_TELEIN)) dbg_msg("m_pTele && TELEIN","ny*m_Width+nx %d",ny*m_Width+nx);
		else if (m_pTele && m_pTele[ny*m_Width+nx].m_Type==TILE_TELEOUT) dbg_msg("TELEOUT","ny*m_Width+nx %d",ny*m_Width+nx);
		else dbg_msg("GetMapIndex(","ny*m_Width+nx %d",ny*m_Width+nx);//REMOVE */

		if(
			(m_pTiles[ny*m_Width+nx].m_Index >= TILE_FREEZE && m_pTiles[ny*m_Width+nx].m_Index <= TILE_NPH) ||
			(m_pFront && (m_pFront[ny*m_Width+nx].m_Index >= TILE_FREEZE && m_pFront[ny*m_Width+nx].m_Index  <= TILE_NPH)) ||
			(m_pTele && (m_pTele[ny*m_Width+nx].m_Type == TILE_TELEIN || m_pTele[ny*m_Width+nx].m_Type == TILE_TELEINEVIL || m_pTele[ny*m_Width+nx].m_Type == TILE_TELEOUT)) ||
			(m_pSpeedup && m_pSpeedup[ny*m_Width+nx].m_Force > 0) ||
			(m_pDoor && m_pDoor[ny*m_Width+nx].m_Index)
		)
		{
			Indices.push_back(ny*m_Width+nx);
			return Indices;
		}
	}

	float a = 0.0f;
	vec2 Tmp = vec2(0, 0);
	int nx = 0;
	int ny = 0;
	int Index,LastIndex = 0;
	for(int i = 0; i < End; i++)
	{
		a = i/d;
		Tmp = mix(PrevPos, Pos, a);
		nx = clamp((int)Tmp.x/32, 0, m_Width-1);
		ny = clamp((int)Tmp.y/32, 0, m_Height-1);
		Index = ny*m_Width+nx;
		//dbg_msg("lastindex","%d",LastIndex);
		//dbg_msg("index","%d",Index);
		if(
			(
				(m_pTiles[ny*m_Width+nx].m_Index >= TILE_FREEZE && m_pTiles[ny*m_Width+nx].m_Index <= TILE_NPH) ||
				(m_pFront && (m_pFront[ny*m_Width+nx].m_Index >= TILE_FREEZE && m_pFront[ny*m_Width+nx].m_Index  <= TILE_NPH)) ||
				(m_pTele && (m_pTele[ny*m_Width+nx].m_Type == TILE_TELEIN || m_pTele[ny*m_Width+nx].m_Type == TILE_TELEINEVIL || m_pTele[ny*m_Width+nx].m_Type == TILE_TELEOUT)) ||
				(m_pSpeedup && m_pSpeedup[ny*m_Width+nx].m_Force > 0) ||
				(m_pDoor && m_pDoor[ny*m_Width+nx].m_Index)
			) &&
			LastIndex != Index
		)
		{
			if(MaxIndices && Indices.size() > MaxIndices) return Indices;
			Indices.push_back(Index);
			LastIndex = Index;
			//dbg_msg("pushed","%d",Index);
		}
	}

	return Indices;
}

vec2 CCollision::GetPos(int Index)
{
	if(Index < 0)
		return vec2(0,0);
	int x = Index%m_Width;
	int y = Index/m_Width;

	return vec2(16+x*32, 16+y*32);
}

int CCollision::GetTileIndex(int Index)
{
	/*dbg_msg("GetTileIndex","m_pTiles[%d].m_Index = %d",Index,m_pTiles[Index].m_Index);//Remove*/
	if(Index < 0)
		return 0;
	return m_pTiles[Index].m_Index;
}

int CCollision::GetFTileIndex(int Index)
{
	/*dbg_msg("GetFTileIndex","m_pFront[%d].m_Index = %d",Index,m_pFront[Index].m_Index);//Remove*/

	if(Index < 0 || !m_pFront)
		return 0;
	return m_pFront[Index].m_Index;
}

int CCollision::GetTileFlags(int Index)
{
	/*dbg_msg("GetTileIndex","m_pTiles[%d].m_Index = %d",Index,m_pTiles[Index].m_Index);//Remove*/
	if(Index < 0)
		return 0;
	return m_pTiles[Index].m_Flags;
}

int CCollision::GetFTileFlags(int Index)
{
	/*dbg_msg("GetFTileIndex","m_pFront[%d].m_Index = %d",Index,m_pFront[Index].m_Index);//Remove*/

	if(Index < 0 || !m_pFront)
		return 0;
	return m_pFront[Index].m_Flags;
}

int CCollision::GetTile(int x, int y)
{
	int nx = clamp(x/32, 0, m_Width-1);
	int ny = clamp(y/32, 0, m_Height-1);
	if(!m_pTiles || ny < 0 || nx < 0)
{
		//dbg_msg("Collision","Something is terribly wrong, !m_pTiles %d, ny %d, ny %d", !m_pTiles, ny, ny);
		return 0;
}
	/*dbg_msg("GetTile","m_Index %d",m_pTiles[ny*m_Width+nx].m_Index);//Remove */
	if(m_pTiles[ny*m_Width+nx].m_Index == COLFLAG_SOLID
		|| m_pTiles[ny*m_Width+nx].m_Index == (COLFLAG_SOLID|COLFLAG_NOHOOK)
		|| m_pTiles[ny*m_Width+nx].m_Index == COLFLAG_DEATH
		|| m_pTiles[ny*m_Width+nx].m_Index == COLFLAG_NOLASER)
		return m_pTiles[ny*m_Width+nx].m_Index;
	else
		return 0;
}

int CCollision::GetFTile(int x, int y)
{
	if(!m_pFront)
	return 0;
	int nx = clamp(x/32, 0, m_Width-1);
	int ny = clamp(y/32, 0, m_Height-1);
	/*dbg_msg("GetFTile","m_Index %d",m_pFront[ny*m_Width+nx].m_Index);//Remove */
	if(m_pFront[ny*m_Width+nx].m_Index == COLFLAG_DEATH
		|| m_pFront[ny*m_Width+nx].m_Index == COLFLAG_NOLASER)
		return m_pFront[ny*m_Width+nx].m_Index;
	else
		return 0;
}

int CCollision::Entity(int x, int y, bool Front)
{
	if((0 > x || x >= m_Width) || (0 > y || y >= m_Height))
	{
		dbg_msg("CCollision::Entity","Something is VERY wrong please report this at github");
		return 0;
	}
	int Index = Front?m_pFront[y*m_Width+x].m_Index:m_pTiles[y*m_Width+x].m_Index;
	return Index-ENTITY_OFFSET;
}

void CCollision::SetCollisionAt(float x, float y, int flag)
{
   int nx = clamp(round(x)/32, 0, m_Width-1);
   int ny = clamp(round(y)/32, 0, m_Height-1);

   m_pTiles[ny * m_Width + nx].m_Index = flag;
}

void CCollision::SetDTile(float x, float y, int Team, bool State)
{
	if(!m_pDoor || ((Team < 0 || Team > (MAX_CLIENTS - 1)) && Team !=99))
		return;
   int nx = clamp(round(x)/32, 0, m_Width-1);
   int ny = clamp(round(y)/32, 0, m_Height-1);

	if(Team == 99)
	{
		for (int i = 0; i < (MAX_CLIENTS - 1); ++i)
		{
			m_pDoor[ny * m_Width + nx].m_Team[i] = State;
		}
	}
   else
	   m_pDoor[ny * m_Width + nx].m_Team[Team] = State;
}

void CCollision::SetDCollisionAt(float x, float y, int Type, int Team, int Flags)
{
	if(!m_pDoor || ((Team < 0 || Team > (MAX_CLIENTS - 1)) && Team !=99))
		return;
   int nx = clamp(round(x)/32, 0, m_Width-1);
   int ny = clamp(round(y)/32, 0, m_Height-1);

   m_pDoor[ny * m_Width + nx].m_Index = Type;
   m_pDoor[ny * m_Width + nx].m_Flags = Flags;// currently only doors in all sides use this so no need for rotation
	if(Team == 99)
	{
		for (int i = 0; i < (MAX_CLIENTS - 1); ++i)
		{
			m_pDoor[ny * m_Width + nx].m_Team[i] = true;
		}
	}
   else
	   m_pDoor[ny * m_Width + nx].m_Team[Team] = true;
}

int CCollision::GetDTileIndex(int Index,int Team)
{
	if(!m_pDoor || Index < 0 || !m_pDoor[Index].m_Index || ((Team < 0 || Team > (MAX_CLIENTS - 1)) && Team !=99))
		return 0;

	if(m_pDoor[Index].m_Team[Team])
		return m_pDoor[Index].m_Index;
	return 0;
}

int CCollision::GetDTileFlags(int Index,int Team)
{
	if(!m_pDoor || Index < 0 || !m_pDoor[Index].m_Index || ((Team < 0 || Team > (MAX_CLIENTS - 1)) && Team !=99))
		return 0;

	if(m_pDoor[Index].m_Team[Team])
		return m_pDoor[Index].m_Flags;
	return 0;
}

// TODO: rewrite this smarter!
void ThroughOffset(vec2 Pos0, vec2 Pos1, int *Ox, int *Oy)
{
	float x = Pos0.x - Pos1.x;
	float y = Pos0.y - Pos1.y;
	if (fabs(x) > fabs(y))
	{
		if (x < 0)
		{
			*Ox = -32;
			*Oy = 0;
		}
		else
		{
			*Ox = 32;
			*Oy = 0;
		}
	}
	else
	{
		if (y < 0)
		{
			*Ox = 0;
			*Oy = -32;
		}
		else
		{
			*Ox = 0;
			*Oy = 32;
		}
	}
}

int CCollision::IntersectLine(vec2 Pos0, vec2 Pos1, vec2 *pOutCollision, vec2 *pOutBeforeCollision, bool AllowThrough)
{
	float d = distance(Pos0, Pos1);
	int End(d+1);
	vec2 Last = Pos0;
	int ix, iy; // Temporary position for checking collision
	int dx, dy; // Offset for checking the "through" tile
	if (AllowThrough)
		{
		ThroughOffset(Pos0, Pos1, &dx, &dy);
		}
	for(int i = 0; i < End; i++)
	{
		float a = i/d;
		vec2 Pos = mix(Pos0, Pos1, a);
		ix = round(Pos.x);
		iy = round(Pos.y);
		if(CheckPoint(ix, iy) && !(AllowThrough && IsThrough(ix + dx, iy + dy)))
		{
			if(pOutCollision)
				*pOutCollision = Pos;
			if(pOutBeforeCollision)
				*pOutBeforeCollision = Last;
			return GetCollisionAt(ix, iy);
		}
		Last = Pos;
	}
	if(pOutCollision)
		*pOutCollision = Pos1;
	if(pOutBeforeCollision)
		*pOutBeforeCollision = Pos1;
	return 0;
}

int CCollision::IntersectNoLaser(vec2 Pos0, vec2 Pos1, vec2 *pOutCollision, vec2 *pOutBeforeCollision)
{
	float d = distance(Pos0, Pos1);
	vec2 Last = Pos0;

	for(float f = 0; f < d; f++)
	{
		float a = f/d;
		vec2 Pos = mix(Pos0, Pos1, a);
		if(IsSolid(round(Pos.x), round(Pos.y)) || (IsNoLaser(round(Pos.x), round(Pos.y)) || IsFNoLaser(round(Pos.x), round(Pos.y))))
		{
			if(pOutCollision)
				*pOutCollision = Pos;
			if(pOutBeforeCollision)
				*pOutBeforeCollision = Last;
			if (IsFNoLaser(round(Pos.x), round(Pos.y)))	return GetFCollisionAt(Pos.x, Pos.y);
			else return GetCollisionAt(Pos.x, Pos.y);
			
		}
		Last = Pos;
	}
	if(pOutCollision)
		*pOutCollision = Pos1;
	if(pOutBeforeCollision)
		*pOutBeforeCollision = Pos1;
	return 0;
}

int CCollision::IntersectNoLaserNW(vec2 Pos0, vec2 Pos1, vec2 *pOutCollision, vec2 *pOutBeforeCollision)
{
	float d = distance(Pos0, Pos1);
	vec2 Last = Pos0;

	for(float f = 0; f < d; f++)
	{
		float a = f/d;
		vec2 Pos = mix(Pos0, Pos1, a);
		if(IsNoLaser(round(Pos.x), round(Pos.y)) || IsFNoLaser(round(Pos.x), round(Pos.y)))
		{
			if(pOutCollision)
				*pOutCollision = Pos;
			if(pOutBeforeCollision)
				*pOutBeforeCollision = Last;
			if(IsNoLaser(round(Pos.x), round(Pos.y))) return GetCollisionAt(Pos.x, Pos.y);
			else return  GetFCollisionAt(Pos.x, Pos.y);
		}
		Last = Pos;
	}
	if(pOutCollision)
		*pOutCollision = Pos1;
	if(pOutBeforeCollision)
		*pOutBeforeCollision = Pos1;
	return 0;
}

int CCollision::IntersectAir(vec2 Pos0, vec2 Pos1, vec2 *pOutCollision, vec2 *pOutBeforeCollision)
{
	float d = distance(Pos0, Pos1);
	vec2 Last = Pos0;

	for(float f = 0; f < d; f++)
	{
		float a = f/d;
		vec2 Pos = mix(Pos0, Pos1, a);
		if(IsSolid(round(Pos.x), round(Pos.y)) || (!GetTile(round(Pos.x), round(Pos.y)) && !GetFTile(round(Pos.x), round(Pos.y))))
		{
			if(pOutCollision)
				*pOutCollision = Pos;
			if(pOutBeforeCollision)
				*pOutBeforeCollision = Last;
			if(!GetTile(round(Pos.x), round(Pos.y)) && !GetFTile(round(Pos.x), round(Pos.y)))
				return -1;
			else
				if (!GetTile(round(Pos.x), round(Pos.y))) return GetTile(round(Pos.x), round(Pos.y));
				else return GetFTile(round(Pos.x), round(Pos.y));
		}
		Last = Pos;
	}
	if(pOutCollision)
		*pOutCollision = Pos1;
	if(pOutBeforeCollision)
		*pOutBeforeCollision = Pos1;
	return 0;
}

// TODO: OPT: rewrite this smarter!
void CCollision::MovePoint(vec2 *pInoutPos, vec2 *pInoutVel, float Elasticity, int *pBounces)
{
	if(pBounces)
		*pBounces = 0;

	vec2 Pos = *pInoutPos;
	vec2 Vel = *pInoutVel;
	if(CheckPoint(Pos + Vel))
	{
		int Affected = 0;
		if(CheckPoint(Pos.x + Vel.x, Pos.y))
		{
			pInoutVel->x *= -Elasticity;
			if(pBounces)
				(*pBounces)++;
			Affected++;
		}

		if(CheckPoint(Pos.x, Pos.y + Vel.y))
		{
			pInoutVel->y *= -Elasticity;
			if(pBounces)
				(*pBounces)++;
			Affected++;
		}

		if(Affected == 0)
		{
			pInoutVel->x *= -Elasticity;
			pInoutVel->y *= -Elasticity;
		}
	}
	else
	{
		*pInoutPos = Pos + Vel;
	}
}

void CCollision::MoveBox(vec2 *pInoutPos, vec2 *pInoutVel, vec2 Size, float Elasticity)
{
	// do the move
	vec2 Pos = *pInoutPos;
	vec2 Vel = *pInoutVel;

	float Distance = length(Vel);
	int Max = (int)Distance;

	if(Distance > 0.00001f)
	{
		//vec2 old_pos = pos;
		float Fraction = 1.0f/(float)(Max+1);
		for(int i = 0; i <= Max; i++)
		{
			//float amount = i/(float)max;
			//if(max == 0)
				//amount = 0;

			vec2 NewPos = Pos + Vel*Fraction; // TODO: this row is not nice

			if(TestBox(vec2(NewPos.x, NewPos.y), Size))
			{
				int Hits = 0;

				if(TestBox(vec2(Pos.x, NewPos.y), Size))
				{
					NewPos.y = Pos.y;
					Vel.y *= -Elasticity;
					Hits++;
				}

				if(TestBox(vec2(NewPos.x, Pos.y), Size))
				{
					NewPos.x = Pos.x;
					Vel.x *= -Elasticity;
					Hits++;
				}

				// neither of the tests got a collision.
				// this is a real _corner case_!
				if(Hits == 0)
				{
					NewPos.y = Pos.y;
					Vel.y *= -Elasticity;
					NewPos.x = Pos.x;
					Vel.x *= -Elasticity;
				}
			}

			Pos = NewPos;
		}
	}

	*pInoutPos = Pos;
	*pInoutVel = Vel;
}

bool CCollision::TestBox(vec2 Pos, vec2 Size)
{
	Size *= 0.5f;
	if(CheckPoint(Pos.x-Size.x, Pos.y-Size.y))
		return true;
	if(CheckPoint(Pos.x+Size.x, Pos.y-Size.y))
		return true;
	if(CheckPoint(Pos.x-Size.x, Pos.y+Size.y))
		return true;
	if(CheckPoint(Pos.x+Size.x, Pos.y+Size.y))
		return true;
	return false;
}

int CCollision::IsSolid(int x, int y)
{
	return (GetTile(x,y)&COLFLAG_SOLID);
}

int CCollision::IsThrough(int x, int y)
{
	int nx = clamp(x/32, 0, m_Width-1);
	int ny = clamp(y/32, 0, m_Height-1);
	int Index = m_pTiles[ny*m_Width+nx].m_Index;
	int Findex = 0;
	if (m_pFront)
		Findex = m_pFront[ny*m_Width+nx].m_Index;
	if (Index == TILE_THROUGH)
		return Index;
	else if (Findex == TILE_THROUGH)
		return Findex;
	else
		return 0;
}

int CCollision::IsNoLaser(int x, int y)
{
   return (CCollision::GetTile(x,y) & COLFLAG_NOLASER);
}

int CCollision::IsFNoLaser(int x, int y)
{
   return (CCollision::GetFTile(x,y) & COLFLAG_NOLASER);
}

int CCollision::IsTeleport(int Index)
{
	if(Index < 0)
		return 0;
	if(!m_pTele)
		return 0;

	int Tele = 0;
	if(m_pTele[Index].m_Type == TILE_TELEIN)
		Tele = m_pTele[Index].m_Number;

	return Tele;
}

int CCollision::IsEvilTeleport(int Index)
{
	if(Index < 0)
		return 0;
	if(!m_pTele)
		return 0;

	int Tele = 0;
	if(m_pTele[Index].m_Type == TILE_TELEINEVIL)
	{
		Tele = m_pTele[Index].m_Number;
		dbg_msg("IsEvilTele","%d",Tele);
	}
	return Tele;
}

int CCollision::IsSpeedup(int Index)
{
	if(Index < 0)
		return 0;
	if(!m_pSpeedup)
		return false;

	if(m_pSpeedup[Index].m_Force > 0)
		return m_pSpeedup[Index].m_Type;

	return 0;
}

void CCollision::GetSpeedup(int Index, vec2 *Dir, int *Force, int *MaxSpeed)
{
	if(Index < 0)
		return;
	vec2 Direction = vec2(1, 0);
	float Angle = m_pSpeedup[Index].m_Angle * (pi / 180.0f);
	*Force = m_pSpeedup[Index].m_Force;
	*Dir = vec2(cos(Angle), sin(Angle));
	if(MaxSpeed)
		*MaxSpeed = m_pSpeedup[Index].m_MaxSpeed;
}

int CCollision::IsCp(int x, int y, int* Flags)
{
	int nx = clamp(x/32, 0, m_Width-1);
	int ny = clamp(y/32, 0, m_Height-1);
	int Index = m_pTiles[ny*m_Width+nx].m_Index;
	*Flags = m_pTiles[ny*m_Width+nx].m_Flags;
	if(Index < 0)
		return 0;
	if (Index == TILE_CP || Index == TILE_CP_F)
		return Index;
	else
		return 0;
}

int CCollision::IsCheckpoint(int Index)
{
	if(Index < 0)
		return -1;
		
	int z = m_pTiles[Index].m_Index;
	if(z >= 35 && z <= 59)
		return z-35;
	return -1;
}

int CCollision::IsFCheckpoint(int Index)
{
	if(Index < 0 || !m_pFront)
		return -1;

	int z = m_pFront[Index].m_Index;
	if(z >= 35 && z <= 59)
		return z-35;
	return -1;
}

vec2 CCollision::CpSpeed(int Index, int Flags)
{
	if(Index < 0)
		return vec2(0,0);
   vec2 target;
   if(Index == TILE_CP || Index == TILE_CP_F)
	   switch(Flags)
	   {
	   case ROTATION_0:
		   target.x=0;
		   target.y=-4;
		   break;
	   case ROTATION_90:
		   target.x=4;
		   target.y=0;
		   break;
	   case ROTATION_180:
		   target.x=0;
		   target.y=4;
		   break;
	   case ROTATION_270:
		   target.x=-4;
		   target.y=0;
		   break;
	   default:
		   target=vec2(0,0);
		   break;
	   }
   if (Index == TILE_CP_F)
       target*=4;
   return target;

}