Ray Casting with different height size
so you obviously know the basics of Wolfenstein raycasting techniques. To add variable height you need to do this:
- add height info on per cell basis
so simply add another value to your cell info in your map table map[][]. You code the stuff as strings that is odd ...
- update scan line render
Somewhere in the code (after hit was detected) you render vertical line per each ray. There you should compute the scan line size something like (assuming y=0 is top of the screen):
y0 = center_of_view_y + projected_half_size
y1 = center_of_view_y - projected_half_size
And should change to:
y0 = center_of_view_y + projected_size
y1 = y0 - 2*projected_half_size*wall_size
Where projected_half_size is the line size computed for constant cell height as you got now, wall_size=<0,1> is scale and center_of_view_y is the y coordinate of the horizon line in your view. This will put your wall on the ground.
- update ray-casting
now when you hit the first wall you stop. With variable wall height you can stop only when you hit wall of full size (wall_size=1) or run out of map. You got 2 option to implement this.
- remember all hits and render in reverse order
- render immediately but only from last rendered height instead of from ground.
The first option is easy to implement but requires more memory and it is slower. The second one is fast and does not need any lists or stacks. But it involves a little bit more math for the scan line render (O(1) if coded right)
I played a bit with my demo from the link at the top. Now the result should look like this:
As you can see the highlighted cells on the map are pass through for rays above their height (so you can see bigger cells behind them).
Beware once you add movement altitude direction (jumps, stairs etc) then the end condition must be different (the rendered scan line hit the top of the view). Also projection part of y coordinate will be different and need to include the actual player altitude.
- add topside
You need to add the rendering of top side. It is similar to rendering ceiling and floor. IIRC original Wolfenstein did not have this capability but the latter pseudo 3D games like DOOM did.
There are more possible approaches like Perspective Vision on Canvas but I think the easiest to implement (as we already got enough info) is to compute the top side part of vertical scanline coordinates in texture and just copy pixels. As we already know where the ray hit the cell and angle of player/camera is also known. For more info see: PCGPE 1.0 Doom techniques
So as a first step add hits for back faces too. That should look like this:
That is done by checking hits of the last hit cell first. Now if you remember the last rendered y coordinate from previous hit (of the same scanline) then if back face is hit instead of rendering the face render top side color from last y to actual y (or copy pixels from floor/ceiling texture instead). Here the green color used for this:
If it helps here is mine C++ (GDI/VCL based) code for this:
//---------------------------------------------------------------------------
//--- Doom 3D engine ver: 1.000 --------------------------------------
//---------------------------------------------------------------------------
#ifndef _Doom3D_h
#define _Doom3D_h
//---------------------------------------------------------------------------
#include <math.h>
#include <jpeg.hpp>
#include "performance.h"
#include "OpenGLrep4d_double.h"
//---------------------------------------------------------------------------
const DWORD _Doom3D_cell_size=10; // 2D map cell size
const DWORD _Doom3D_wall_size=100; // full height of wall in map
#define _Doom3D_filter_txr
//---------------------------------------------------------------------------
class Doom3D
{
public:
DWORD mxs,mys,**pmap; // 2D map // txr + height<<16
DWORD sxs,sys,**pscr; // pseudo 3D screen
Graphics::TBitmap *scr;
DWORD txs,tys,**ptxr,tn; // 2D textures
Graphics::TBitmap *txr,*txr2; // textures, texture mipmaps resolution: /2 and /4
double plrx,plry,plrz,plra; // player position [x,y,z,angle]
double view_ang; // [rad] view angle
double focus; // [cells] view focal length
struct _ray
{
double x,y,l; // hit or end of map position
DWORD hit; // map cell of hit or 0xFFFFFFFF
char typ; // H/V
_ray() {};
_ray(_ray& a) { *this=a; }
~_ray() {};
_ray* operator = (const _ray *a) { *this=*a; return this; }
//_ray* operator = (const _ray &a) { ..copy... return this; }
};
_ray *ray; // ray[sxs]
keytab keys;
DWORD txr_sel;
DWORD cell_h;
Doom3D();
Doom3D(Doom3D& a) { *this=a; }
~Doom3D();
Doom3D* operator = (const Doom3D *a) { *this=*a; return this; }
//Doom3D* operator = (const Doom3D &a) { ..copy... return this; }
void map_resize(DWORD xs,DWORD ys); // change map resolution
void map_height(DWORD height); // set height for whole map to convert maps from Wolfenstein3D demo
void map_clear(); // clear whole map
void map_save(AnsiString name);
void map_load(AnsiString name);
void scr_resize(DWORD xs,DWORD ys);
void txr_load(AnsiString name);
void draw();
void update(double dt);
void mouse(double x,double y,TShiftState sh)
{
x=floor(x/_Doom3D_cell_size); if (x>=mxs) x=mxs-1; if (x<0) x=0;
y=floor(y/_Doom3D_cell_size); if (y>=mys) y=mys-1; if (y<0) y=0;
DWORD xx=x,yy=y;
keys.setm(x,y,sh);
if (keys.Shift.Contains(ssLeft )) pmap[yy][xx]=(txr_sel)|(cell_h<<16);
if (keys.Shift.Contains(ssRight)) pmap[yy][xx]=0xFFFFFFFF;
keys.rfsmouse();
}
void wheel(int delta,TShiftState sh)
{
if (sh.Contains(ssShift))
{
if (delta<0) { cell_h-=10; if (cell_h<10) cell_h=10; }
if (delta>0) { cell_h+=10; if (cell_h>_Doom3D_wall_size) cell_h=_Doom3D_wall_size; }
}
else{
if (delta<0) { txr_sel--; if (txr_sel==0xFFFFFFFF) txr_sel=tn-1; }
if (delta>0) { txr_sel++; if (txr_sel== tn) txr_sel= 0; }
}
}
};
//---------------------------------------------------------------------------
Doom3D::Doom3D()
{
mxs=0; mys=0; pmap=NULL;
sxs=0; sys=0; scr=new Graphics::TBitmap; pscr=NULL; ray=NULL;
txs=0; tys=0; txr=new Graphics::TBitmap; ptxr=NULL; tn=0;
txr2=new Graphics::TBitmap;
plrx=0.0; plry=0.0; plrz=0.0; plra=0.0;
view_ang=60.0*deg;
focus=0.25;
txr_sel=0;
cell_h=_Doom3D_wall_size;
txr_load("textures128x128.jpg");
map_resize(16,16);
map_load("Doom3D_map.dat");
}
//---------------------------------------------------------------------------
Doom3D::~Doom3D()
{
DWORD y;
map_save("Doom3D_map.dat");
if (pmap) { for (y=0;y<mys;y++) delete[] pmap[y]; delete[] pmap; pmap=NULL; } if (ray) delete[] ray; ray=NULL;
if (pscr) { delete[] pscr; pscr=NULL; } if (scr) delete scr; scr=NULL;
if (ptxr) { delete[] ptxr; ptxr=NULL; } if (txr) delete txr; txr=NULL;
if (txr2) delete txr2; txr2=NULL;
}
//---------------------------------------------------------------------------
void Doom3D::map_resize(DWORD xs,DWORD ys)
{
DWORD y;
if (pmap) { for (y=0;y<mys;y++) delete[] pmap[y]; delete[] pmap; pmap=NULL; }
mys=ys; mxs=xs; pmap=new DWORD*[mys]; for (y=0;y<mys;y++) pmap[y]=new DWORD[mxs];
map_clear();
plrx=(mxs-1)*0.5; plry=(mys-1)*0.5; plrz=0.0; plra=0.0*deg;
}
//---------------------------------------------------------------------------
void Doom3D::map_height(DWORD h)
{
DWORD x,y,c;
for (y=0;y<mys;y++)
for (x=0;x<mxs;x++)
{
c=pmap[y][x];
c&=0xFFFF;
c|=h<<16;
pmap[y][x]=c;
}
}
//---------------------------------------------------------------------------
void Doom3D::map_clear()
{
DWORD x,y,c;
for (y=0;y<mys;y++)
for (x=0;x<mxs;x++)
{
c=0xFFFFFFFF;
if ((x==0)||(x==mxs-1)) c=0;
if ((y==0)||(y==mys-1)) c=0;
pmap[y][x]=c;
}
}
//---------------------------------------------------------------------------
void Doom3D::map_save(AnsiString name)
{
int hnd=FileCreate(name); if (hnd<0) return;
DWORD y;
y=' PAM';
FileWrite(hnd,&y ,4); // id
FileWrite(hnd,&mxs,4); // x resolution
FileWrite(hnd,&mys,4); // y resolution
for (y=0;y<mys;y++) // map
FileWrite(hnd,pmap[y],mxs<<2);
y=' RLP';
FileWrite(hnd,&y ,4); // id
FileWrite(hnd,&plrx,8);
FileWrite(hnd,&plry,8);
FileWrite(hnd,&plrz,8);
FileWrite(hnd,&plra,8);
FileClose(hnd);
}
//---------------------------------------------------------------------------
void Doom3D::map_load(AnsiString name)
{
int hnd=FileOpen(name,fmOpenRead); if (hnd<0) return;
DWORD x,y;
y=' PAM'; FileRead(hnd,&x ,4); // id
if (x==y)
{
FileRead(hnd,&x,4); // x resolution
FileRead(hnd,&y,4); // y resolution
map_resize(x,y);
for (y=0;y<mys;y++) // map
FileRead(hnd,pmap[y],mxs<<2);
}
y=' RLP'; FileRead(hnd,&x ,4); // id
if (x==y)
{
FileRead(hnd,&plrx,8);
FileRead(hnd,&plry,8);
FileRead(hnd,&plrz,8);
FileRead(hnd,&plra,8);
}
FileClose(hnd);
}
//---------------------------------------------------------------------------
void Doom3D::scr_resize(DWORD xs,DWORD ys)
{
scr->HandleType=bmDIB;
scr->PixelFormat=pf32bit;
scr->SetSize(xs,ys);
sxs=scr->Width;
sys=scr->Height;
delete[] pscr; pscr=new DWORD*[sys];
for (DWORD y=0;y<sys;y++) pscr[y]=(DWORD*)scr->ScanLine[y];
if (ray) delete[] ray; ray=new _ray[sxs];
}
//---------------------------------------------------------------------------
void Doom3D::txr_load(AnsiString name)
{
AnsiString ext=ExtractFileExt(name).LowerCase();
for(;;)
{
if (ext==".bmp")
{
txr->LoadFromFile(name);
break;
}
if (ext==".jpg")
{
TJPEGImage *jpg=new TJPEGImage;
if (jpg==NULL) return;
jpg->LoadFromFile(name);
txr->Assign(jpg);
delete jpg;
break;
}
return;
}
DWORD y=tys;
txr->HandleType=bmDIB;
txr->PixelFormat=pf32bit;
txs=txr->Width;
tys=txr->Height;
// mip map
txr2->SetSize(txs>>1,(tys>>1)+(tys>>2));
txr2->Canvas->StretchDraw(TRect(0, 0,txs>>1,tys>>1),txr);
txr2->Canvas->StretchDraw(TRect(0,tys>>1,txs>>2,(tys>>1)+(tys>>2)),txr);
tn=txs/tys; txs=tys;
delete[] ptxr; ptxr=new DWORD*[tys];
for (y=0;y<tys;y++) ptxr[y]=(DWORD*)txr->ScanLine[y];
}
//---------------------------------------------------------------------------
void Doom3D::draw()
{
// total time measurement
tbeg(); double tperf0=performance_tms;
AnsiString tcls,tray,tmap,ttotal;
double a,a0,da,dx,dy,l,mx,my;
DWORD x,y,xs2,ys2,c,m;
double xx0,yy0,dx0,dy0,ll0; DWORD c0,d0;
double xx1,yy1,dx1,dy1,ll1; DWORD c1,d1;
_ray *p;
xs2=sxs>>1;
ys2=sys>>1;
// aspect ratio,view angle corrections
a=90.0*deg-view_ang;
double wall=double(sxs)*(1.25+(0.288*a)+(2.04*a*a)); // [px]
// floor,ceilling/sky
tbeg();
for (y=0;y<ys2;y++) for (x=0;x<sxs;x++) pscr[y][x]=0x000080FF;
for ( ;y<sys;y++) for (x=0;x<sxs;x++) pscr[y][x]=0x00404040;
tend(); tcls=tstr(1)+" cls";
// [cast rays]
tbeg();
// diffuse + ambient lighting
DWORD ch=155.0+fabs(100.0*sin(plra));
DWORD cv=155.0+fabs(100.0*cos(plra));
a0=plra-(0.5*view_ang);
da=divide(view_ang,sxs-1);
mx=mxs; my=mys;
for (p=ray,a=a0,x=0;x<sxs;x++,a+=da,p++)
{
p->x=plrx;
p->y=plry;
p->hit=0xFFFFFFFF;
p->typ=' ';
p->l=1.0e20;
ll0=ll1=p->l;
// grid V-line hits
c0=0; dx0=cos(a);
if (dx0<0.0) { c0=1; xx0=floor(plrx)-0.001; dx0=-1.0; }
if (dx0>0.0) { c0=1; xx0=ceil (plrx)+0.001; dx0=+1.0; }
if (c0) { dy0=tan(a); yy0=plry+((xx0-plrx)*dy0); dy0*=dx0; dx=xx0-plrx; dy=yy0-plry; ll0=(dx*dx)+(dy*dy); }
// grid H-line hits
c1=0; dy1=sin(a);
if (dy1<0.0) { c1=1; yy1=floor(plry)-0.001; dy1=-1.0; }
if (dy1>0.0) { c1=1; yy1=ceil (plry)+0.001; dy1=+1.0; }
if (c1) { dx1=divide(1.0,tan(a)); xx1=plrx+((yy1-plry)*dx1); dx1*=dy1; dx=xx1-plrx; dy=yy1-plry; ll1=(dx*dx)+(dy*dy); }
int height0=sys; // already rendered height [pixels]
bool _hit,_back=false,_bck=true;
if (!c0) ll0=1e20;
if (!c1) ll1=1e20;
for (;c0||c1;)
{
_hit=false;
// grid V-line hits
if (c0)
{
if (xx0<0.0) { c0=0; ll0=1e20; }
if (xx0>=mx) { c0=0; ll0=1e20; }
if (yy0<0.0) { c0=0; ll0=1e20; }
if (yy0>=my) { c0=0; ll0=1e20; }
}
if ((c0)&&(ll0<ll1))
{
m=DWORD(xx0-dx0);
if ((m>=0.0)&&(m<mxs)&&(!_bck)){ c=pmap[DWORD(yy0)][ m ]; if ((c&0xFFFF)!=0xFFFF) { p->hit=c; p->typ='V'; p->l=ll0; p->x=xx0; p->y=yy0; _hit=true; _back=true; _bck=true; }}
if (!_hit) { c=pmap[DWORD(yy0)][DWORD(xx0)]; if ((c&0xFFFF)!=0xFFFF) { p->hit=c; p->typ='V'; p->l=ll0; p->x=xx0; p->y=yy0; _hit=true; _back=false; _bck=false; } xx0+=dx0; dx=xx0-plrx; yy0+=dy0; dy=yy0-plry; ll0=(dx*dx)+(dy*dy); }
}
// grid H-line hits
if (c1)
{
if (xx1<0.0) { c1=0; ll1=1e20; }
if (xx1>=mx) { c1=0; ll1=1e20; }
if (yy1<0.0) { c1=0; ll1=1e20; }
if (yy1>=my) { c1=0; ll1=1e20; }
}
if ((c1)&&(ll0>ll1)&&(!_hit))
{
m=DWORD(yy1-dy1);
if ((m>=0.0)&&(m<mys)&&(!_bck)){ c=pmap[ m ][DWORD(xx1)]; if ((c&0xFFFF)!=0xFFFF) { p->hit=c; p->typ='H'; p->l=ll1; p->x=xx1; p->y=yy1; _hit=true; _back=true; _bck=true; }}
if (!_hit) { c=pmap[DWORD(yy1)][DWORD(xx1)]; if ((c&0xFFFF)!=0xFFFF) { p->hit=c; p->typ='H'; p->l=ll1; p->x=xx1; p->y=yy1; _hit=true; _back=false; _bck=false; } xx1+=dx1; dx=xx1-plrx; yy1+=dy1; dy=yy1-plry; ll1=(dx*dx)+(dy*dy); }
}
// render scan line
if (_hit)
{
union { DWORD dd; BYTE db[4]; } cc;
int tx,ty,sy,sy0,sy1,cnt,dsy,dty;
p->l=sqrt(p->l)*cos(a-plra);// anti fish eye
m=divide(wall*focus,p->l); // projected wall half size
c=0;
if (p->typ=='H') { c=ch; tx=double(double(txs)*(p->x-floor(p->x))); }
if (p->typ=='V') { c=cv; tx=double(double(txs)*(p->y-floor(p->y))); }
tx+=txs*(p->hit&0xFFFF);
// prepare interpolation
sy1=ys2+m;
// sy0=ys2-m; // constant wall height
sy0=sy1-(((m+m)*(p->hit>>16))/_Doom3D_wall_size); // variable wall height
dty=tys-1;
dsy=sy1-sy0+1;
// skip sy>=sys
if (sy1>=sys) sy1=sys-1;
// skip sy<0
for (cnt=dsy,sy=sy0,ty=0;sy<0;sy++) { cnt-=dty; while (cnt<=0) { cnt+=dsy; ty++; }}
#ifdef _Doom3D_filter_txr
DWORD r=0,g=0,b=0,n=0;
#else
cc.dd=ptxr[ty][tx];
cc.db[0]=DWORD((DWORD(cc.db[0])*c)>>8);
cc.db[1]=DWORD((DWORD(cc.db[1])*c)>>8);
cc.db[2]=DWORD((DWORD(cc.db[2])*c)>>8);
#endif
// continue sy>=0
y=height0;
if (sy1>height0) sy1=height0;
if (sy0<height0) height0=sy0;
if (_back){ for (sy=sy0;sy<=y;sy++){ if ((sy>0)&&(sy<sys)) pscr[sy][x]=0x0000FF00; }}
else for (;sy<=sy1;sy++)
{
#ifdef _Doom3D_filter_txr
if (!n)
{
cc.dd=ptxr[ty][tx];
b+=DWORD(cc.db[0]);
g+=DWORD(cc.db[1]);
r+=DWORD(cc.db[2]); n+=256;
}
if ((sy>0)&&(sy<sys))
{
cc.db[0]=DWORD(c*b/n); b=0;
cc.db[1]=DWORD(c*g/n); g=0;
cc.db[2]=DWORD(c*r/n); r=0; n=0;
pscr[sy][x]=cc.dd;
}
cnt-=dty; while (cnt<=0)
{
cnt+=dsy; ty++;
cc.dd=ptxr[ty][tx];
b+=DWORD(cc.db[0]);
g+=DWORD(cc.db[1]);
r+=DWORD(cc.db[2]); n+=256;
}
#else
if ((sy>0)&&(sy<sys)) pscr[sy][x]=cc.dd;
cnt-=dty; while (cnt<=0)
{
cnt+=dsy; ty++;
cc.dd=ptxr[ty][tx];
cc.db[0]=DWORD((DWORD(cc.db[0])*c)>>8);
cc.db[1]=DWORD((DWORD(cc.db[1])*c)>>8);
cc.db[2]=DWORD((DWORD(cc.db[2])*c)>>8);
}
#endif
}
if (height0<0) break;
}
}
}
tend(); tray=tstr(1)+" ray";
// [2D map]
tbeg();
m=_Doom3D_cell_size;
mx=_Doom3D_cell_size;
if ((sxs>=mxs*m)&&(sys>=mys*m))
{
for (y=0;y<mys*m;y++) // pmap[][]
for (x=0;x<mxs*m;x++)
{
if ((pmap[y/m][x/m]&0xFFFF)!=0xFFFF) c=0x00808080; else c=0x00000000;
pscr[y][x]=c;
}
x=double(plrx*mx); // view rays
y=double(plry*mx);
scr->Canvas->Pen->Color=0x00005050;
scr->Canvas->Pen->Mode=pmMerge;
for (c=0;c<sxs;c++)
{
scr->Canvas->MoveTo(x,y);
scr->Canvas->LineTo(DWORD(ray[c].x*mx),DWORD(ray[c].y*mx));
}
scr->Canvas->Pen->Mode=pmCopy;
c=focus*m; // player and view direction
scr->Canvas->Pen->Color=0x000000FF;
scr->Canvas->Brush->Color=0x000000FF;
scr->Canvas->MoveTo(x,y);
scr->Canvas->LineTo(DWORD(ray[xs2].x*mx),DWORD(ray[xs2].y*mx));
scr->Canvas->Ellipse(x-c,y-c,x+c,y+c);
scr->Canvas->Pen->Color=0x00202020;
for (y=0;y<=mys;y++) // map grid
for (x=0;x<=mxs;x++)
{
scr->Canvas->MoveTo(0 ,y*m);
scr->Canvas->LineTo(mxs*m,y*m);
scr->Canvas->MoveTo(x*m, 0);
scr->Canvas->LineTo(x*m,mys*m);
}
x=keys.mx*m; // selected cell
y=keys.my*m;
scr->Canvas->Pen->Color=0x0020FFFF;
scr->Canvas->MoveTo(x ,y );
scr->Canvas->LineTo(x+m,y );
scr->Canvas->LineTo(x+m,y+m);
scr->Canvas->LineTo(x ,y+m);
scr->Canvas->LineTo(x ,y );
}
tend(); tmap=tstr(1)+" map";
// [editor]
if (txr_sel!=0xFFFFFFFF)
{
int x=sxs,y=5,s0,s1,s2,i,j;
s0=txs>>1;
s1=txs>>2;
s2=(s0*cell_h)/_Doom3D_wall_size;
for (i=-3;i<=3;i++)
{
j=txr_sel+i;
while (j< 0) j+=tn;
while (j>=tn) j-=tn;
if (i) { scr->Canvas->CopyRect(TRect(x-s1,y+(s1>>1),x,s1+(s1>>1)),txr2->Canvas,TRect(s1*j,s0,s1*j+s1,s0+s1)); x-=s1+5; }
else { scr->Canvas->CopyRect(TRect(x-s0,y+s0-s2 ,x,s0 ),txr2->Canvas,TRect(s0*j, 0,s0*j+s0,s2 )); x-=s0+5; }
}
}
// total time measurement
performance_tms=tperf0;
tend(); ttotal=tstr(1)+" total";
x=m*mxs+m;
c=16; y=-c;
scr->Canvas->Font->Color=clYellow;
scr->Canvas->Brush->Style=bsClear;
scr->Canvas->TextOutA(x,y+=c,AnsiString().sprintf("player: %.2lf x %.2lf x %.2lf",plrx,plry,plrz));
scr->Canvas->TextOutA(x,y+=c,AnsiString().sprintf(" mouse: %.2lf x %.2lf",keys.mx,keys.my));
scr->Canvas->TextOutA(x,y+=c,tray);
scr->Canvas->TextOutA(x,y+=c,tcls);
scr->Canvas->TextOutA(x,y+=c,tmap);
scr->Canvas->TextOutA(x,y+=c,ttotal);
scr->Canvas->TextOutA(x,y+=c,AnsiString().sprintf(" key: %d",keys.Key));
// aspect ratio test
/*
c=ys2*7/10;
scr->Canvas->Rectangle(xs2-c,ys2-c,xs2+c,ys2+c);
*/
// cross
c=4,m=32;
scr->Canvas->Pen->Color=clRed;
scr->Canvas->MoveTo(xs2-c,ys2-m);
scr->Canvas->LineTo(xs2-c,ys2-c);
scr->Canvas->LineTo(xs2-m,ys2-c);
scr->Canvas->MoveTo(xs2+c,ys2-m);
scr->Canvas->LineTo(xs2+c,ys2-c);
scr->Canvas->LineTo(xs2+m,ys2-c);
scr->Canvas->MoveTo(xs2-c,ys2+m);
scr->Canvas->LineTo(xs2-c,ys2+c);
scr->Canvas->LineTo(xs2-m,ys2+c);
scr->Canvas->MoveTo(xs2+c,ys2+m);
scr->Canvas->LineTo(xs2+c,ys2+c);
scr->Canvas->LineTo(xs2+m,ys2+c);
scr->Canvas->Brush->Style=bsSolid;
}
//---------------------------------------------------------------------------
void Doom3D::update(double dt)
{
int move=0;
double da=120.0*deg*dt;
double dl= 5.0 *dt;
double dx=0.0,dy=0.0,dz=0.0;
if (keys.get(104)) { plra-=da; if (plra< 0.0) plra+=pi2; } // turn l/r
if (keys.get(105)) { plra+=da; if (plra>=pi2) plra-=pi2; }
if (keys.get(101)) { move=1; dx=+dl*cos(plra); dy=+dl*sin(plra); } // move f/b
if (keys.get( 98)) { move=1; dx=-dl*cos(plra); dy=-dl*sin(plra); }
if (keys.get(102)) { move=1; dx= dl*cos(plra-90*deg); dy=dl*sin(plra-90*deg); } // strafe l/r
if (keys.get( 99)) { move=1; dx= dl*cos(plra+90*deg); dy=dl*sin(plra+90*deg); }
if (keys.get(100)) { move=1; dz=+dl; } // strafe u/d
if (keys.get( 97)) { move=1; dz=-dl; }
if (move) // update/test plr position
{
double x,y,z,mx,my;
x=plrx+dx; mx=mxs-focus;
y=plry+dy; my=mys-focus;
z=plrz+dz; if ((z>=0.0)&&(z<=_Doom3D_wall_size)) plrz=z;;
if (x<focus) x=focus; if (x>mx) x=mx;
if (y<focus) y=focus; if (y>my) y=my;
dx*=divide(focus,dl);
dy*=divide(focus,dl);
if ((pmap[DWORD(y+dy)][DWORD(x+dx)]&0xFFFF)==0xFFFF) { plrx=x; plry=y; }
else if ((pmap[DWORD(y+dy)][DWORD(x )]&0xFFFF)==0xFFFF) plry=y;
else if ((pmap[DWORD(y )][DWORD(x+dx)]&0xFFFF)==0xFFFF) plrx=x;
}
keys.rfskey();
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
#endif
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
Just ignore the performance.h time measurement tbeg,tend,tstr, OpenGLrep4d_double.h keyboard and mouse handler keytab and port VCL related stuff (Canvas,AnsiString,File access, JPEG...).
If you need help with understand the gfx stuff see
- Display an array of color in C
The usage of this class is simple declare an object of this class, and add the event to your window (mouse,keyboard,repaint ...). My VCL Window (single form with one timer on it) code looks like this:
//$$---- Form CPP ----
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "win_main.h"
#include "Doom3D.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMain *Main;
Doom3D game;
//---------------------------------------------------------------------------
void TMain::draw()
{
game.draw();
Canvas->Draw(0,0,game.scr);
}
//---------------------------------------------------------------------------
__fastcall TMain::TMain(TComponent* Owner) : TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TMain::FormResize(TObject *Sender)
{
game.scr_resize(ClientWidth,ClientHeight);
}
//---------------------------------------------------------------------------
void __fastcall TMain::tim_redrawTimer(TObject *Sender)
{
game.update(tim_redraw->Interval*0.001);
draw();
}
//---------------------------------------------------------------------------
void __fastcall TMain::FormKeyDown(TObject *Sender, WORD &Key,TShiftState Shift){ game.keys.set(Key,Shift); }
void __fastcall TMain::FormKeyUp(TObject *Sender, WORD &Key, TShiftState Shift) { game.keys.rst(Key,Shift); }
void __fastcall TMain::FormActivate(TObject *Sender) { game.keys.reset_keys(); }
//---------------------------------------------------------------------------
void __fastcall TMain::FormMouseMove(TObject *Sender, TShiftState Shift, int X, int Y) { game.mouse(X,Y,Shift); }
void __fastcall TMain::FormMouseDown(TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) { game.mouse(X,Y,Shift); }
void __fastcall TMain::FormMouseUp (TObject *Sender, TMouseButton Button, TShiftState Shift, int X, int Y) { game.mouse(X,Y,Shift); }
void __fastcall TMain::FormMouseWheel(TObject *Sender, TShiftState Shift, int WheelDelta, TPoint &MousePos, bool &Handled) { game.wheel(WheelDelta,Shift); Handled=true; }
//---------------------------------------------------------------------------
And here the main iteration variables explanation:
And here the texture file:
Here is how it looks like after some more code tweaking and perspective correct texture mapping:
Here related QA to this one:
- Efficient floor/ceiling rendering in Raycaster
And more recent demo version (with map editor):
- win32 stand alone raycast demo
Raycast Players Distance to Grid Intersection
(Apologies for formatting below; I'm tapping this out on a phone)
From trigonometry, cos(aplha) = (length of red line)/(length of hypotenuse).
Therefore: length of hypotenuse = (length of red line)/cos(alpha).
You'd use sin for a vertical intersection.
A word of caution though: if you think about what would happen when the player is looking directly at a wall, all the lengths should be the same so that it's a constant height on screen, but they'll actually be different because the diagonals are different. You need to multiply by cos of the relative angle between the player's direction and the casting direction (so, if you've a 60 degree field of view then 0 at the centre of the display, off to +30 at one end and down to -30 at the other).
Also don't fall into the common trap of thinking that the angles you cast at should be evenly spaced. Think again of a person looking directly at a wall and use atan to get the proper relative angles.
Ray Casting floor with HTML canvas
There are two small mistakes in your code.
var directDistFloor = this.screenDist * (canvas.height/2) / Math.floor(i);
This should calculate the distance between the player and a floor tile. If we look up the actual value of this.screenDist we can see:
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