我正在尝试编写一个光线投射引擎。
我研究了http://www.instructables.com/id/Making-a-Basic-3D-Engine-in-Java/上的教程和http://lodev.org/cgtutor/raycasting上的 C++ 光线投射教程.html，经过几次尝试后，我将光线投射到正确的方向，因此得到了（半）工作输出。
我让墙壁出现在世界上，我在游戏中添加了运动，我能够四处走动。但是，无论我面对世界的哪个方向，墙壁（应该是立方体）都只显示立方体的两侧。因此，它不会显示一个实心立方体，而是从立方体实际上最靠近相机的一侧跳转，而是显示立方体的另一侧，这仅在我面向原点时发生（0,0 ) 我的地图存储在其中的 2d 数组。此错误如上图所示。
我认为这个错误是由于整数四舍五入和光线检测到的墙壁的位置被四舍五入造成的，但我似乎无法提出解决方案。我实际上为每个像素列投射了两条光线，一条用于检测垂直墙壁，一条用于检测水平墙壁。计算并比较每个的距离，然后绘制最短距离的墙。
我的问题是如何正确绘制墙壁
public class Screen {
//VARIABLE DECLARATIONS
//-----------------------
int FOV = 60; //field of view in degrees
int screenwidth = 800; //variable holds the vertical resolution of the screen
int screenheight = 600; //variable holds the horizontal resolution of the screen
double camx; //cameras x coordinate
double camy; //cameras y coordinate
double camAngle; //direction of camera in degrees
double rayAngle; //angle of ray being cast in radians
int x = 0; //holds the current pixel column being looped through
double IncrementAngle = (double)FOV / (double)screenwidth; //calculates the change in the rays angle for each horizontal pixel
int[][] map; //stores the 2d map that represents the 3d world of the game
public Screen() {
public int[] update(int[] pixels, int[][] m, double ca, double cx, double cy, int fov) {
FOV = fov;
IncrementAngle = (double)FOV / (double)screenwidth; //calculates the change in the rays angle for each horizontal pixel
camAngle = ca;
camx = cx;
camy = cy;
map = m;
int x = 0;
Color c; //declares new color
//fills background
for (int n = 0; n < pixels.length; n++) pixels[n] = Color.BLACK.getRGB();
for (double ray = (double)(FOV / 2); ray > (double)(-FOV / 2); ray -= IncrementAngle) {
double vdist = Integer.MAX_VALUE, hdist = Integer.MAX_VALUE;
double perpendicularDist = 0;
double theta;
double lineheight;
int drawstart, drawend;
int side = 0;
int r = 0, g = 0, b = 0, a = 0; //variables that determinbe what colours will be drawn (red, green, blue, and alpha for
transparency)
rayAngle = Math.toRadians(camAngle + ray);
try {
vdist = VertDist(rayAngle);
}
catch (ArrayIndexOutOfBoundsException e) {}
try {
hdist = HorDist(rayAngle);
}
catch (ArrayIndexOutOfBoundsException e) {}
theta = Math.abs(rayAngle - Math.toRadians(camAngle)); //angle difference between the ray being cast and the cameras
direction
if (hdist < vdist) {
perpendicularDist = hdist * Math.cos(theta);
lastSide = 0;
r = Color.GRAY.getRed();
g = Color.GRAY.getGreen();
b = Color.GRAY.getBlue();
a = Color.GRAY.getAlpha();
}
else {
perpendicularDist = vdist * Math.cos(theta);
lastSide = 1;
r = Color.DARK_GRAY.getRed();
g = Color.DARK_GRAY.getGreen();
b = Color.DARK_GRAY.getBlue();
a = Color.DARK_GRAY.getAlpha();
}
//creates pulsating effect with wall colours
r -= pulse;
g += pulse * 2;
b -= pulse;
c = new Color(r, g, b, a);
lineheight = screenheight / perpendicularDist;
drawstart = (int)(-lineheight / 2) + (screenheight / 2);
drawend = (int)(lineheight / 2) + (screenheight / 2);
if (drawstart < 0) drawstart = 0;
if (drawend >= screenheight) drawend = screenheight - 1;
for (int y = drawstart; y < drawend; y++) {
pixels[x + (y * screenwidth)] = c.getRGB();
}
if (x < screenwidth) x++;
else x = 0;
}
//returns pixels array to main class to be shown to screen
return pixels;
}
public double VertDist(double angle) {
double rx = 0, ry = 0;
double stepX = 0, stepY = 0;
double FstepX = 0, FstepY = 0;
double Fxcomp = 0, Fycomp = 0;
double xcomp = 0, ycomp = 0;
double mapx = camx, mapy = camy;
boolean hit = false;
double obliqueDist = 0;
rx = Math.cos(angle);
ry = Math.sin(angle);
if (rx < 0) {
stepX = -1;
FstepX = (camx - ((int)camx)) * stepX;
}
else if (rx > 0) {
stepX = 1;
FstepX = ((int)(camx + 1)) - camx;
}
ycomp = (stepX * Math.tan(angle) * -1);
Fycomp = Math.abs(FstepX) * ycomp;
if (map[(int)(mapx)][(int)(mapy)] > 0) hit = true;
mapx += FstepX;
mapy += Fycomp;
if (map[(int)(mapx)][(int)(mapy)] > 0) hit = true;
else {
while (!hit && mapx > 0 && mapy > 0) { //loops while a wall has not been found and while positive indexes are still being
checked
mapx += stepX;
mapy += ycomp;
if (map[(int)(mapx)][(int)(mapy)] > 0) {
hit = true;
//if (Math.toDegrees(rayAngle) < 270 && Math.toDegrees(rayAngle) > 90) {
// mapy -= stepX;
// mapx -= ycomp;
//}
}
}
}
mapx = Math.abs(mapx - camx);
mapy = Math.abs(mapy - camy);
obliqueDist = Math.sqrt((mapx*mapx) + (mapy*mapy));
//change to be not fixed angle based
//if (angle > Math.toRadians(135) && angle < Math.toRadians(225)) {
// obliqueDist -= Math.sqrt(stepX*stepX + ycomp*ycomp);
//}
return obliqueDist;
}
public double HorDist(double angle) {
double rx, ry;
double stepX = 0, stepY = 0;
double FstepX = 0, FstepY = 0;
double Fxcomp, Fycomp;
double xcomp, ycomp;
double mapx = camx, mapy = camy;
boolean hit = false;
double obliqueDist = 0;
rx = Math.cos(angle);
ry = Math.sin(angle);
if (ry < 0) {
stepY = 1;
FstepY = ((int)(camy + 1)) - camy;
}
else if (ry > 0) {
stepY = -1;
FstepY = (camy - (int)camy) * stepY;
}
xcomp = stepY / (Math.tan(angle) * -1);
Fxcomp = Math.abs(FstepY) * xcomp;
if (map[(int)(mapx)][(int)(mapy)] > 0) hit = true;
mapx += Fxcomp;
mapy += FstepY;
if (map[(int)(mapx)][(int)(mapy)] > 0) hit = true;
else {
while (!hit) {
mapx += xcomp;
mapy += stepY;
if (map[(int)(mapx)][(int)(mapy)] > 0) hit = true;
}
}
mapx = Math.abs(mapx - camx);
mapy = Math.abs(mapy - camy);
obliqueDist = Math.sqrt((mapx*mapx) + (mapy*mapy));
//change to be not fixed angle based
//if (angle > Math.toRadians(45) && angle < Math.toRadians(135)) {
// obliqueDist -= Math.sqrt(xcomp*xcomp + stepY*stepY);
//}
return obliqueDist;
} }