scummvm/boxes.cpp

/* ScummVM - Scumm Interpreter
 * Copyright (C) 2001  Ludvig Strigeus
 * Copyright (C) 2001/2002 The ScummVM project
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * $Header$
 *
 */

#include "stdafx.h"
#include "scumm.h"
#include "math.h"

byte Scumm::getMaskFromBox(int box) {
	Box *ptr = getBoxBaseAddr(box);
	if (!ptr)
		return 0;
	return ptr->mask;
}

byte Scumm::getBoxFlags(int box) {
	Box *ptr = getBoxBaseAddr(box);
	if (!ptr)
		return 0;
	return ptr->flags;
}

int Scumm::getBoxScale(int box) {
	if(_features & GF_NO_SCALLING)
		return(255);
	Box *ptr = getBoxBaseAddr(box);
	if (!box)
		return 255;
	return FROM_LE_16(ptr->scale);
}

byte Scumm::getNumBoxes() {
	byte *ptr = getResourceAddress(rtMatrix, 2);
	if (!ptr) return 0;
	return ptr[0];
}

Box *Scumm::getBoxBaseAddr(int box) {
        byte *ptr = getResourceAddress(rtMatrix, 2);
		if (!ptr) 
			return NULL;
	checkRange(ptr[0]-1, 0, box, "Illegal box %d");
        if(_features & GF_SMALL_HEADER) {
		if (_features & GF_OLD256) 
			return (Box*)(ptr + box*(SIZEOF_BOX-2) + 1);		
		else
                        return (Box*)(ptr + box*SIZEOF_BOX + 1);
        } else
		return (Box*)(ptr + box*SIZEOF_BOX + 2);
}

bool Scumm::checkXYInBoxBounds(int b, int x, int y) {
	BoxCoords box;

	if (b==0 && (!(_features & GF_SMALL_HEADER)))
		return 0;

	getBoxCoordinates(b, &box);

	if (x < box.ul.x && x < box.ur.x &&
		x < box.ll.x && x < box.lr.x)
			return 0;
	
	if (x > box.ul.x && x > box.ur.x &&
		x > box.ll.x && x > box.lr.x)
			return 0;
	
	if (y < box.ul.y && y < box.ur.y &&
		y < box.ll.y && y < box.lr.y)
			return 0;

	if (y > box.ul.y && y > box.ur.y &&
		y > box.ll.y && y > box.lr.y)
			return 0;
	
	if (box.ul.x == box.ur.x &&
		box.ul.y == box.ur.y &&
		box.ll.x == box.lr.x &&
		box.ll.y == box.lr.y ||
		box.ul.x == box.lr.x &&
		box.ul.y == box.lr.y &&
		box.ur.x== box.ll.x &&
		box.ur.y== box.ll.y) {

		ScummPoint pt;
		pt = closestPtOnLine(box.ul.x, box.ul.y, box.ll.x, box.ll.y, x, y);
		if (distanceFromPt(x, y, pt.x,pt.y) <= 4)
			return 1;
	}
	
	if (!getSideOfLine(
		box.ul.x, box.ul.y, box.ur.x, box.ur.y, x,y,b))
			return 0;
	
	if (!getSideOfLine(
		box.ur.x, box.ur.y, box.ll.x, box.ll.y, x,y,b))
			return 0;

	if (!getSideOfLine(
		box.ll.x, box.ll.y, box.lr.x, box.lr.y, x,y,b))
			return 0;

	if (!getSideOfLine(
		box.lr.x, box.lr.y, box.ul.x, box.ul.y, x,y,b))
			return 0;

	return 1;
}

void Scumm::getBoxCoordinates(int boxnum, BoxCoords *box) {
	Box *bp = getBoxBaseAddr(boxnum);

	box->ul.x = (int16)FROM_LE_16(bp->ulx);
	box->ul.y = (int16)FROM_LE_16(bp->uly);
	box->ur.x = (int16)FROM_LE_16(bp->urx);
	box->ur.y = (int16)FROM_LE_16(bp->ury);

	if(_features & GF_OLD256)
	{
		box->ll.x = (int16)FROM_LE_16(bp->lrx);
		box->ll.y = (int16)FROM_LE_16(bp->lry);
		box->lr.x = (int16)FROM_LE_16(bp->llx);
		box->lr.y = (int16)FROM_LE_16(bp->lly);
	}
	else
	{
		box->ll.x = (int16)FROM_LE_16(bp->llx);
		box->ll.y = (int16)FROM_LE_16(bp->lly);
		box->lr.x = (int16)FROM_LE_16(bp->lrx);
		box->lr.y = (int16)FROM_LE_16(bp->lry);
	}
	
}

uint Scumm::distanceFromPt(int x, int y, int ptx, int pty) {
	int diffx, diffy;
	
	diffx = abs(ptx-x);

	if (diffx >= 0x100)
		return 0xFFFF;
	
	diffy = abs(pty - y);

	if (diffy >= 0x100)
		return 0xFFFF;
	diffx *= diffx;
	diffy *= diffy;
	return diffx + diffy;
}

bool Scumm::getSideOfLine(int x1,int y1, int x2, int y2, int x, int y, int box) {
	return (x-x1)*(y2-y1) <= (y-y1)*(x2-x1);
}

ScummPoint Scumm::closestPtOnLine(int ulx, int uly, int llx, int lly, int x, int y) {
	int lydiff,lxdiff;
	int32 dist,a,b,c;
	int x2,y2;
	ScummPoint pt;

	if (llx==ulx) {
		x2 = ulx;
		y2 = y;
	} else if (lly==uly) {
		x2 = x;
		y2 = uly;
	} else {
		lydiff = lly - uly;

		lxdiff = llx - ulx;

		if (abs(lxdiff) > abs(lydiff)) {
			dist = lxdiff * lxdiff + lydiff * lydiff;

			a = ulx * lydiff / lxdiff;
			b = x * lxdiff / lydiff;

			c = (a + b - uly + y) * lydiff * lxdiff / dist;

			x2 = c;
			y2 = c * lydiff / lxdiff - a + uly;
		} else {
			dist = lydiff * lydiff + lxdiff * lxdiff;

			a = uly * lxdiff / lydiff;
			b = y * lydiff / lxdiff;
			
			c = (a + b - ulx + x) * lydiff * lxdiff / dist;

			y2 = c;
			x2 = c * lxdiff / lydiff - a + ulx;
		}
	}

	lxdiff = llx - ulx;
	lydiff = lly - uly;

	if (abs(lydiff) < abs(lxdiff)) {
		if (lxdiff > 0) {
			if (x2 < ulx) {
type1:;
				x2 = ulx;
				y2 = uly;
			} else if (x2 > llx) {
type2:;
				x2 = llx;
				y2 = lly;
			}
		} else {
			if (x2 > ulx) goto type1;
			if (x2 < llx) goto type2;
		}
	} else {
		if (lydiff > 0) {
			if (y2 < uly) goto type1;
			if (y2 > lly) goto type2;
		} else {
			if (y2 > uly) goto type1;
			if (y2 < lly) goto type2;
		}
	}

	pt.x = x2;
	pt.y = y2;
	return pt;
}

bool Scumm::inBoxQuickReject(int b, int x, int y, int threshold) {
	int t;
	BoxCoords box;

	getBoxCoordinates(b, &box);

	if (threshold==0)
		return 1;
	
	t = x - threshold;
	if (t > box.ul.x && t > box.ur.x &&
		t > box.ll.x && t > box.lr.x)
			return 0;
	
	t = x + threshold;
	if (t < box.ul.x && t < box.ur.x &&
		t < box.ll.x && t < box.lr.x)
			return 0;
	
	t = y - threshold;
	if (t > box.ul.y && t > box.ur.y &&
		t > box.ll.y && t > box.lr.y)
			return 0;
	
	t = y + threshold;
	if (t < box.ul.y && t < box.ur.y &&
			t < box.ll.y && t < box.lr.y)
			return 0;

	return 1;
}

AdjustBoxResult Scumm::getClosestPtOnBox(int b, int x, int y) {
	ScummPoint pt;
	AdjustBoxResult best;
	uint dist;
	uint bestdist = (uint)0xFFFF;
	BoxCoords box;

	getBoxCoordinates(b, &box);

	pt = closestPtOnLine(box.ul.x,box.ul.y,box.ur.x,box.ur.y,x,y);
	dist = distanceFromPt(x, y, pt.x, pt.y);
	if (dist < bestdist) {
		bestdist = dist;
		best.x = pt.x;
		best.y = pt.y;
	}

	pt = closestPtOnLine(box.ur.x,box.ur.y,box.ll.x,box.ll.y,x,y);
	dist = distanceFromPt(x, y, pt.x, pt.y);
	if (dist < bestdist) {
		bestdist = dist;
		best.x = pt.x;
		best.y = pt.y;
	}

	pt = closestPtOnLine(box.ll.x,box.ll.y,box.lr.x,box.lr.y,x,y);
	dist = distanceFromPt(x, y, pt.x, pt.y);
	if (dist < bestdist) {
		bestdist = dist;
		best.x = pt.x;
		best.y = pt.y;
	}

	pt = closestPtOnLine(box.lr.x,box.lr.y,box.ul.x,box.ul.y,x,y);
	dist = distanceFromPt(x, y, pt.x, pt.y);
	if (dist < bestdist) {
		bestdist = dist;
		best.x = pt.x;
		best.y = pt.y;
	}
	
	best.dist = bestdist;
	return best;
}

byte *Scumm::getBoxMatrixBaseAddr() {
	byte *ptr = getResourceAddress(rtMatrix, 1);
	if (*ptr==0xFF) ptr++;
	return ptr;
}

int Scumm::getPathToDestBox(byte from, byte to) {
	byte *boxm;
	byte i;

	if (from==to)
		return to;
	
	boxm = getBoxMatrixBaseAddr();

	i=0;
	while (i != from) {
		while (*boxm != 0xFF)
			boxm += 3;
		i++;
		boxm++;
	}

	while (boxm[0]!=0xFF) {
		if (boxm[0] <= to && boxm[1]>=to)
			return boxm[2];
		boxm+=3;
	}
	return -1;
}

int Scumm::findPathTowards(Actor *a, byte box1nr, byte box2nr, byte box3nr) {
	BoxCoords box1;
	BoxCoords box2;
	ScummPoint tmp;
	int i,j;
	int flag;
	int q,pos;

	getBoxCoordinates(box1nr,&box1);
	getBoxCoordinates(box2nr,&box2);

	for(i=0; i<4; i++) {
		for(j=0; j<4; j++) {
			if (box1.ul.x==box1.ur.x &&
					box1.ul.x==box2.ul.x &&
					box1.ul.x==box2.ur.x) {
				flag = 0;
				if (box1.ul.y > box1.ur.y) {
					SWAP(box1.ul.y, box1.ur.y);
					flag |= 1;
				}

				if (box2.ul.y > box2.ur.y) {
					SWAP(box2.ul.y, box2.ur.y);
					flag |= 2;
				}

				if (box1.ul.y > box2.ur.y || box2.ul.y > box1.ur.y ||
						(box1.ur.y==box2.ul.y || box2.ur.y==box1.ul.y) &&
						box1.ul.y!=box1.ur.y && box2.ul.y!=box2.ur.y) {
					if (flag&1)
						SWAP(box1.ul.y, box1.ur.y);
					if (flag&2)
						SWAP(box2.ul.y, box2.ur.y);
				} else {
					if (box2nr == box3nr) {
						int diffX = a->walkdata.destx - a->x;
						int diffY = a->walkdata.desty - a->y;
						int boxDiffX = box1.ul.x - a->x;
						
						if (diffX!=0) {
							int t;

							diffY *= boxDiffX;
							t = diffY / diffX;
							if (t==0 && (diffY<=0 || diffX<=0) && (diffY>=0 || diffX>=0))
								t = -1;
							pos = a->y + t;
						} else {
							pos = a->y;
						}
					} else {
						pos = a->y;
					}

					q = pos;
					if (q < box2.ul.y)
					q = box2.ul.y;
					if (q > box2.ur.y)
						q = box2.ur.y;
					if (q < box1.ul.y)
						q = box1.ul.y;
					if (q > box1.ur.y)
						q = box1.ur.y;
					if (q==pos && box2nr==box3nr)
						return 1;
					_foundPathY = q;
					_foundPathX = box1.ul.x;
					return 0;
				}
			}

			if (box1.ul.y==box1.ur.y &&
					box1.ul.y==box2.ul.y &&
					box1.ul.y==box2.ur.y) {
				flag = 0;
				if (box1.ul.x > box1.ur.x) {
					SWAP(box1.ul.x, box1.ur.x);
					flag |= 1;
				}

				if (box2.ul.x > box2.ur.x) {
					SWAP(box2.ul.x, box2.ur.x);
					flag |= 2;
				}

				if (box1.ul.x > box2.ur.x || box2.ul.x > box1.ur.x ||
						(box1.ur.x==box2.ul.x || box2.ur.x==box1.ul.x) &&
						box1.ul.x!=box1.ur.x && box2.ul.x!=box2.ur.x) {
					if (flag&1)
						SWAP(box1.ul.x, box1.ur.x);
					if (flag&2)
						SWAP(box2.ul.x, box2.ur.x);
				} else {

					if (box2nr == box3nr) {
						int diffX = a->walkdata.destx - a->x;
						int diffY = a->walkdata.desty - a->y;
						int boxDiffY = box1.ul.y - a->y;
						
						pos = a->x;
						if (diffY!=0) {
							pos += diffX * boxDiffY / diffY;
						}
					} else {
						pos = a->x;
					}

					q = pos;
					if (q < box2.ul.x)
						q = box2.ul.x;
					if (q > box2.ur.x)
						q = box2.ur.x;
					if (q < box1.ul.x)
						q = box1.ul.x;
					if (q > box1.ur.x)
						q = box1.ur.x;
					if (q==pos && box2nr==box3nr)
						return 1;
					_foundPathX = q;
					_foundPathY = box1.ul.y;
					return 0;
				}
			}
			tmp = box1.ul;
			box1.ul = box1.ur;
			box1.ur = box1.ll;
			box1.ll = box1.lr;
			box1.lr = tmp;
		}
		tmp = box2.ul;
		box2.ul = box2.ur;
		box2.ur = box2.ll;
		box2.ll = box2.lr;
		box2.lr = tmp;
	}
	return 0;
}
void Scumm::setBoxFlags(int box, int val) {
	/* FULL_THROTTLE stuff */
	if (val & 0xC000) {
		assert(box>=0 && box<65);
		_extraBoxFlags[box] = val;
	} else {
		Box *b = getBoxBaseAddr(box);
		b->flags = val;
	}
}

void Scumm::setBoxScale(int box, int scale) {
	Box *b = getBoxBaseAddr(box);
	b->scale = scale;
}

#define BOX_MATRIX_SIZE 2000

void Scumm::createBoxMatrix() {
	byte *matrix_ptr;
	int num,i,j;
	byte flags;
	int table_1[66],table_2[66];
	int counter,val;
	int code;

	PathVertex *vtx;
	PathNode *node, *node2=NULL;

	_maxBoxVertexHeap = 1000;

	createResource(rtMatrix, 4, 1000);
	createResource(rtMatrix, 3, 4160); //65 items of something of size 64
	createResource(rtMatrix, 1, BOX_MATRIX_SIZE);

	matrix_ptr = getResourceAddress(rtMatrix, 1);

	_boxMatrixPtr4 = getResourceAddress(rtMatrix, 4);
	_boxMatrixPtr1 = getResourceAddress(rtMatrix, 1);
	_boxMatrixPtr3 = getResourceAddress(rtMatrix, 3);

	_boxPathVertexHeapIndex = _boxMatrixItem = 0;
	
	num = getNumBoxes();

	for (i=0; i<num; i++) {
		for (j=0; j<num; j++) {
			if (i==j) {
				_boxMatrixPtr3[i*64+j] = 0;	
			} else if (areBoxesNeighbours(i, j)) {
				_boxMatrixPtr3[i*64+j] = 1;
			} else {
				_boxMatrixPtr3[i*64+j] = 250;
			}
		}
	}

	for (j=0; j<num; j++) {
		flags = getBoxFlags(j);
		if (flags & 0x80) {
			addToBoxMatrix(0xFF);
			addToBoxMatrix(j);
			addToBoxMatrix(j);
			addToBoxMatrix(j);
		} else {
			vtx = addPathVertex();
			for (i=0; i<num; i++) {
				flags = getBoxFlags(j);
				if (!(flags&0x80)) {
					node = unkMatrixProc2(vtx, i);
					if (i==j)
						node2 = node;
				}
			}
			table_1[j] = 0;
			table_2[j] = j;
			vtx = unkMatrixProc1(vtx, node2);
			node = vtx ? vtx->left : NULL;

			counter = 250;
			while (node) {
				val = _boxMatrixPtr3[j*64 + node->index];
				table_1[node->index] = val;
				if (val<counter) counter=val;
				
				if (table_1[node->index]!=250)
					table_2[node->index] = node->index;
				else
					table_2[node->index] = -1;

				node = node->left;
			}
			
			while (vtx) {
				counter = 250;
				node2 = node = vtx->left;

				while (node) {
					if ( table_1[node->index] < counter ) {
						counter = table_1[node->index];
						node2 = node;
					}
					node = node->left;
				}
				vtx = unkMatrixProc1(vtx, node2);
				node = vtx ? vtx->left : NULL;
				while (node) {
					code = _boxMatrixPtr3[node2->index * 64 + node->index];
					code += table_1[node2->index];
					if (code < table_1[node->index]) {
						table_1[node->index] = code;
						table_2[node->index] = table_2[node2->index];
					}
					node = node->left;
				}
			}

			addToBoxMatrix(0xFF);
			for (i=1; i<num;) {
				if (table_2[i-1]!=-1) {
					addToBoxMatrix(i-1); /* lo */
					if (table_2[i-1] != table_2[i]) {
						addToBoxMatrix(i-1); /* hi */
						addToBoxMatrix(table_2[i-1]); /* dst */
					} else {
						while (table_2[i-1] == table_2[i]) {
							if (++i==num)
								break;
						}
						addToBoxMatrix(i-1); /* hi */
						addToBoxMatrix(table_2[i-1]); /* dst */
					}
				}
				if (++i==num && table_2[i-1]!=-1) {
					addToBoxMatrix(i-1); /* lo */
					addToBoxMatrix(i-1); /* hi */
					addToBoxMatrix(table_2[i-1]); /* dest */
				}
			}
		}
	}

	addToBoxMatrix(0xFF);
	nukeResource(rtMatrix, 4);
	nukeResource(rtMatrix, 3);
}

PathVertex *Scumm::unkMatrixProc1(PathVertex *vtx, PathNode *node) {
	if (node==NULL || vtx==NULL)
		return NULL;

	if (!node->right) {
		vtx->left = node->left;
	} else {
		node->right->left = node->left;
	}

	if (!node->left) {
		vtx->right = node->right;
	} else {
		node->left->right = node->right;
	}

	if (vtx->left)
		return vtx;

	return NULL;
}

PathNode *Scumm::unkMatrixProc2(PathVertex *vtx, int i) {
	PathNode *node;

	if (vtx==NULL)
		return NULL;

	if (!vtx->right) {
		node = (PathNode*)addToBoxVertexHeap(sizeof(PathNode));
		vtx->left = vtx->right = node;

		node->index = i;
		node->left = 0;
		node->right = 0;
	} else {
		node = (PathNode*)addToBoxVertexHeap(sizeof(PathNode));	
		vtx->right->left = node;
		
		node->right = vtx->right;
		node->index = i;
		node->left = 0;

		vtx->right = node;
	}

	return vtx->right;
}

/* Check if two boxes are neighbours */
bool Scumm::areBoxesNeighbours(int box1nr, int box2nr) {
	int j,k,m,n;
	int tmp_x, tmp_y;
	bool result;
	BoxCoords box;
	BoxCoords box2;

	if (getBoxFlags(box1nr)&0x80 || getBoxFlags(box2nr)&0x80)
		return false;

	getBoxCoordinates(box1nr, &box2);
	getBoxCoordinates(box2nr, &box);
	
	result = false;
	j = 4;
	
	do {
		k = 4;
		do {
			if (box2.ur.x == box2.ul.x &&
				  box.ul.x == box2.ul.x &&
					box.ur.x == box2.ur.x) {
				n = m = 0;
				if (box2.ur.y < box2.ul.y) {
					n = 1;
					SWAP(box2.ur.y, box2.ul.y);
				}
				if (box.ur.y < box.ul.y) {
					m = 1;
					SWAP(box.ur.y, box.ul.y);
				}
				if (box.ur.y < box2.ul.y ||
					  box.ul.y > box2.ur.y ||
						(box.ul.y == box2.ur.y ||
						 box.ur.y==box2.ul.y) &&
						 box2.ur.y != box2.ul.y &&
						 box.ul.y!=box.ur.y) {
					if (n) {
						SWAP(box2.ur.y, box2.ul.y);
					}
					if (m) {
						SWAP(box.ur.y, box.ul.y);
					}
				} else {
					if (n) {
						SWAP(box2.ur.y, box2.ul.y);
					}
					if (m) {
						SWAP(box.ur.y, box.ul.y);
					}
					result = true;
				}	
			}

			if (box2.ur.y == box2.ul.y && 
					box.ul.y == box2.ul.y &&
					box.ur.y == box2.ur.y) {
				n = m = 0;
				if (box2.ur.x < box2.ul.x) {
					n = 1;
					SWAP(box2.ur.x, box2.ul.x);
				}
				if (box.ur.x < box.ul.x) {
					m = 1;
					SWAP(box.ur.x, box.ul.x);
				}
				if (box.ur.x < box2.ul.x ||
					  box.ul.x > box2.ur.x ||
						(box.ul.x == box2.ur.x ||
						 box.ur.x==box2.ul.x) &&
						 box2.ur.x != box2.ul.x &&
						 box.ul.x!=box.ur.x) {

					if (n) {
						SWAP(box2.ur.x, box2.ul.x);
					}
					if (m) {
						SWAP(box.ur.x, box.ul.x);
					}
				} else {
					if (n) {
						SWAP(box2.ur.x, box2.ul.x);
					}
					if (m) {
						SWAP(box.ur.x, box.ul.x);
					}
					result = true;
				}
			}
			
			tmp_x = box2.ul.x;
			tmp_y = box2.ul.y;
			box2.ul.x = box2.ur.x;
			box2.ul.y = box2.ur.y;
			box2.ur.x = box2.ll.x;
			box2.ur.y = box2.ll.y;
			box2.ll.x = box2.lr.x;
			box2.ll.y = box2.lr.y;
			box2.lr.x = tmp_x;
			box2.lr.y = tmp_y;
		} while (--k);
		
		tmp_x = box.ul.x;
		tmp_y = box.ul.y;
		box.ul.x = box.ur.x;
		box.ul.y = box.ur.y;
		box.ur.x = box.ll.x;
		box.ur.y = box.ll.y;
		box.ll.x = box.lr.x;
		box.ll.y = box.lr.y;
		box.lr.x = tmp_x;
		box.lr.y = tmp_y;
	} while (--j);

	return result;
}

void Scumm::addToBoxMatrix(byte b) {
	if (++_boxMatrixItem > BOX_MATRIX_SIZE)
		error("Box matrix overflow");
	*_boxMatrixPtr1++ = b;
}

void *Scumm::addToBoxVertexHeap(int size) {
	byte *ptr = _boxMatrixPtr4;

	_boxMatrixPtr4 += size;
	_boxPathVertexHeapIndex += size;

	if (_boxPathVertexHeapIndex >= _maxBoxVertexHeap)
		error("Box path vertex heap overflow");

	return ptr;
}

PathVertex *Scumm::addPathVertex() {
	_boxMatrixPtr4 = getResourceAddress(rtMatrix, 4);
	_boxPathVertexHeapIndex = 0;

	return (PathVertex*)addToBoxVertexHeap(sizeof(PathVertex));
}

int Scumm::findPathTowardsOld(Actor *a, byte trap1, byte trap2, byte final_trap)
{
        GetGates(trap1,trap2);
	ScummPoint pt;

        p[1].x = actor->x;
        p[1].y = actor->y;
        p[2].x = 32000;
        p[3].x = 32000;
        p[4].x = 32000;

        if (trap2 == final_trap) {                                                              /* next = final box? */
                p[4].x = actor->walkdata.destx;
                p[4].y = actor->walkdata.desty;

                if (getMaskFromBox(trap1) == getMaskFromBox(trap2) || 1) {
                        if (CompareSlope(p[1].x,p[1].y,p[4].x,p[4].y, gate1ax,gate1ay) !=
                                 CompareSlope(p[1].x,p[1].y,p[4].x,p[4].y, gate1bx,gate1by) &&
                                 CompareSlope(p[1].x,p[1].y,p[4].x,p[4].y, gate2ax,gate2ay) !=
                                 CompareSlope(p[1].x,p[1].y,p[4].x,p[4].y, gate2bx,gate2by)) {
                                return 0;         /* same zplane and between both gates? */
                        }
                }
        }

       	pt=closestPtOnLine(gate2ax,gate2ay,gate2bx,gate2by,p[1].x,p[1].y);
        p[3].x = pt.x;
        p[3].y = pt.y;

        if (CompareSlope(p[1].x,p[1].y,p[3].x,p[3].y, gate1ax,gate1ay) ==
                 CompareSlope(p[1].x,p[1].y,p[3].x,p[3].y, gate1bx,gate1by)) {
                closestPtOnLine(gate1ax,gate1ay,gate1bx,gate1by,p[1].x,p[1].y);
                p[2].x = pt.x;                       /* if point 2 between gates, ignore! */
                p[2].y = pt.y;
        }

        return 0;
}

void Scumm::GetGates(int trap1,int trap2) {
int   i;
int    Closest1=0,Closest2=0,Closest3=0;
int    Dist[8];
int Dist1,Dist2,Dist3;
int Box1,Box2,Box3;
BoxCoords box;
int polyx[8];
int polyy[8];
AdjustBoxResult pt;

        getBoxCoordinates(trap1,&box);
        polyx[0] = box.ul.x;
        polyy[0] = box.ul.y;
        polyx[1] = box.ur.x;
        polyy[1] = box.ur.y;
        polyx[2] = box.ll.x;
        polyy[2] = box.ll.y;
        polyx[3] = box.lr.x;
        polyy[3] = box.lr.y;
        for (i = 0 ; i < 4 ; i++) { 
		pt = getClosestPtOnBox(trap2,polyx[i],polyy[i]);
		Dist[i] = pt.dist;
                CloX[i] = pt.x;
                CloY[i] = pt.y;
        }

        getBoxCoordinates(trap2,&box);
        polyx[4] = box.ul.x;
        polyy[4] = box.ul.y;
        polyx[5] = box.ur.x;
        polyy[5] = box.ur.y;
        polyx[6] = box.ll.x;
        polyy[6] = box.ll.y;
        polyx[7] = box.lr.x;
        polyy[7] = box.lr.y;
        for (i = 4 ; i < 8 ; i++) {
                pt = getClosestPtOnBox(trap1,polyx[i],polyy[i]);
                Dist[i] = pt.dist;
                CloX[i] = pt.x;
                CloY[i] = pt.y;
        }


        Dist1 = 0xFFFF;
        for (i = 0 ; i < 8 ; i++) {
                if (Dist[i] < Dist1) {
                        Dist1 = Dist[i];
                        Closest1 = i;
                }
        }
        Dist[Closest1] = 0xFFFF;

        Dist2 = 0xFFFF;
        for (i = 0 ; i < 8 ; i++) {
                if (Dist[i] < Dist2) {
                        Dist2 = Dist[i];
                        Closest2 = i;
                }
        }
        Dist[Closest2] = 0xFFFF;

        Dist3 = 0xFFFF;
        for (i = 0 ; i < 8 ; i++) {
                if (Dist[i] < Dist3) {
                        Dist3 = Dist[i];
                        Closest3 = i;
                }
        }

        Box1 = (Closest1 > 3);
        Box2 = (Closest2 > 3);
        Box3 = (Closest3 > 3);

        Dist1 = (int)sqrt(Dist1);
        Dist2 = (int)sqrt(Dist2);
        Dist3 = (int)sqrt(Dist3);
        
	if (Box1 == Box2 && abs(Dist1-Dist2) < 4) {
                SetGate(Closest1,Closest2,polyx,polyy);

        } else if (Box1 == Box2 && Dist1 == Dist2) {                            /* parallel */
                SetGate(Closest1,Closest2,polyx,polyy);
        } else if (Box1 == Box3 && Dist1 == Dist3) {                            /* parallel */
                SetGate(Closest1,Closest3,polyx,polyy);
        } else if (Box2 == Box3 && Dist2 == Dist3) {                            /* parallel */
                SetGate(Closest2,Closest3,polyx,polyy);


        } else if (Box1 == Box3 && abs(Dist1-Dist3) < 4) {
                SetGate(Closest1,Closest3,polyx,polyy);
        } else if (abs(Dist1-Dist3) < 4) {  /* if 1 close to 3 then use 2-3 */
                SetGate(Closest2,Closest3,polyx,polyy);
        } else if (abs(Dist1-Dist2) < 4) {
                SetGate(Closest1,Closest2,polyx,polyy);
        } else {
                SetGate(Closest1,Closest1,polyx,polyy);
        }
}

int Scumm::CompareSlope(int X1,int Y1,int X2,int Y2,int X3,int Y3)
{
        if ((Y2 - Y1) * (X3 - X1) > (Y3 - Y1) * (X2 - X1)) return(0);
        return(1);
}

void Scumm::SetGate(int line1,int line2, int polyx[8], int polyy[8])
{

        if (line1 < 4) {                                                                /* from box 1 to box 2 */
                gate1ax = polyx[line1];
                gate1ay = polyy[line1];
                gate2ax = CloX[line1];
                gate2ay = CloY[line1];

        } else {
                gate2ax = polyx[line1];
                gate2ay = polyy[line1];
                gate1ax = CloX[line1];
                gate1ay = CloY[line1];
        }

        if (line2 < 4) {                                                                /* from box */
                gate1bx = polyx[line2];
                gate1by = polyy[line2];
                gate2bx = CloX[line2];
                gate2by = CloY[line2];

        } else {
                gate2bx = polyx[line2];
                gate2by = polyy[line2];
                gate1bx = CloX[line2];
                gate1by = CloY[line2];
        }
}