public Renderer(int screenWidth, int screenHeight)
{
ScreenWidth = screenWidth;
ScreenHeight = screenHeight;
WallSlices = new WallSlice[screenWidth];
WallSlicesY = new WallSlice[screenWidth];
}
private void DrawDirectionalSprite(SpriteBatch spriteBatch, Camera camera, Map map, GameObject sprite)
{
//translate sprite position to relative to camera
double spriteX = sprite.Position.X - camera.Position.X;
double spriteY = sprite.Position.Y - camera.Position.Y;
int spriteMapX = (int)sprite.Position.X;
int spriteMapY = (int)sprite.Position.Y;
Texture2D tex = sprite.Texture;
int texWidth = tex.Width;
int texHeight = tex.Height;
double objectOffset = 0;
if (sprite.Orientation == Orientation.None)
{
string errorMessage = "";
errorMessage = String.Format("The orientation of the Sprite in the location [{0}],[{1}] has not been defined!", sprite.Position.X.ToString(), sprite.Position.Y.ToString());
throw new Exception(errorMessage);
}
Orientation spriteOrientation = sprite.Orientation;
//Find the sprite offset, that is how deep is the sprite inside the block depending on the orientation X or Y
if (spriteOrientation == Orientation.Horizontal)
{
if (camera.Plane.X > 0)
{
objectOffset = (sprite.Position.Y - (int)sprite.Position.Y);
}
else
{
objectOffset = 1 - (sprite.Position.Y - (int)sprite.Position.Y);
}
}
else
{
if (camera.Plane.Y < 0)
{
objectOffset = (sprite.Position.X - (int)sprite.Position.X);
}
else
{
objectOffset = 1 - (sprite.Position.X - (int)sprite.Position.X);
}
}
double transformY = 0;
double transformStartY = 0;
double transformEndY = 0;
int drawStartX = 0;
int drawEndX = 0;
int drawCenterX = ComputeScreenX(camera, spriteX, spriteY, out transformY);
// add or substract 0.5 because the position of the sprite is the middle
if (spriteOrientation == Orientation.Horizontal)
{
drawStartX = ComputeScreenX(camera, spriteX - 0.5, spriteY, out transformStartY);
drawEndX = ComputeScreenX(camera, spriteX + 0.5, spriteY, out transformEndY);
}
else
{
drawStartX = ComputeScreenX(camera, spriteX, spriteY - 0.5, out transformStartY);
drawEndX = ComputeScreenX(camera, spriteX, spriteY + 0.5, out transformEndY);
}
//validate sprite's start and end
if (drawStartX < 0)
{
drawStartX = 0;
}
if (drawStartX > ScreenWidth)
{
drawStartX = ScreenWidth;
}
if (drawEndX < 0)
{
drawEndX = 0;
}
if (drawEndX > ScreenWidth)
{
drawEndX = ScreenWidth;
}
//switch variables depending on the orientation of the camera
if (drawStartX > drawEndX)
{
int tempX = drawStartX;
drawStartX = drawEndX;
drawEndX = tempX;
}
//temporal slices for the sprite
WallSlice[] spriteSlices = new WallSlice[drawEndX - drawStartX];
//loop through every vertical stripe of the sprite on screen
for (int x = drawStartX; x < drawEndX; x++)
{
//x-coordinate in camera space
double cameraX = 2 * x / (double)ScreenWidth - 1;
double rayPosX = camera.Position.X;
double rayPosY = camera.Position.Y;
double rayDirX = camera.Direction.X + camera.Plane.X * cameraX;
double rayDirY = camera.Direction.Y + camera.Plane.Y * cameraX;
//which box of the map we're in
int mapX = (int)rayPosX;
int mapY = (int)rayPosY;
//length of ray from current position to next x or y-side
double sideDistX = 0;
double sideDistY = 0;
//length of ray from one x or y-side to next x or y-side
double deltaDistX = Math.Sqrt(1 + (rayDirY * rayDirY) / (rayDirX * rayDirX));
double deltaDistY = Math.Sqrt(1 + (rayDirX * rayDirX) / (rayDirY * rayDirY));
double perpWallDist = 0;
//what direction to step in x or y-direction (either +1 or -1)
int stepX = 0;
int stepY = 0;
int side = 0; //was a NS or a EW wall hit?
if (spriteOrientation == Orientation.Horizontal)
{
side = 1;
}
else
{
side = 0;
}
//calculate step and initial sideDist
if (rayDirX < 0)
{
stepX = -1;
sideDistX = (rayPosX - mapX) * deltaDistX;
}
else
{
stepX = 1;
sideDistX = (mapX + 1.0 - rayPosX) * deltaDistX;
}
if (rayDirY < 0)
{
stepY = -1;
sideDistY = (rayPosY - mapY) * deltaDistY;
}
else
{
stepY = 1;
sideDistY = (mapY + 1.0 - rayPosY) * deltaDistY;
}
mapX = spriteMapX;
mapY = spriteMapY;
//Calculate distance projected on camera direction (oblique distance will give fisheye effect!)
if (side == 0)
{
perpWallDist = Math.Abs((mapX - rayPosX + (1 - stepX) / 2.0) / rayDirX) + Math.Abs(objectOffset / rayDirX);
}
else
{
perpWallDist = Math.Abs((mapY - rayPosY + (1 - stepY) / 2.0) / rayDirY) + Math.Abs(objectOffset / rayDirY);
}
//Calculate height of line to draw on screen
int lineHeight = (int)Math.Abs(ScreenHeight / perpWallDist);
//calculate lowest and highest pixel to fill in current stripe
int drawStart = -lineHeight / 2 + ScreenHeight / 2;
int drawEnd = lineHeight / 2 + ScreenHeight / 2;
//calculate value of wallX
//where exactly the wall was hit
double wallX;
if (side == 0)
{
//vertical
wallX = rayPosY + ((mapX - rayPosX + (1 - stepX) / 2.0) / rayDirX + Math.Abs(objectOffset / rayDirX)) * rayDirY;
}
else
{
//horizontal
wallX = rayPosX + (((mapY - rayPosY + (1 - stepY) / 2.0) / rayDirY) + Math.Abs(objectOffset / rayDirY)) * rayDirX;
}
wallX -= Math.Floor(wallX);
double spriteCenter = 0;
//Find the sprite center relative to the block containg it
if (spriteOrientation == Orientation.Horizontal)
{
spriteCenter = (sprite.Position.X - (int)sprite.Position.X);
}
else
{
spriteCenter = (sprite.Position.Y - (int)sprite.Position.Y);
}
//Map correctly the texture depending on center of the sprite.
//By default the center is an offset of 0.5 in X or Y axis
if (spriteCenter > 0.5)
{
wallX = wallX - (spriteCenter - 0.5);
}
else if (spriteCenter < 0.5)
{
wallX = wallX - (spriteCenter + 0.5);
}
if (wallX < 0)
{
wallX = 1 + wallX;
}
//x coordinate on the texture
int texX = (int)(wallX * (double)texWidth);
spriteSlices[x - drawStartX].Depth = perpWallDist;
spriteSlices[x - drawStartX].Height = lineHeight;
spriteSlices[x - drawStartX].TextureX = texX;
spriteSlices[x - drawStartX].Texture = tex;
}
//Draw the stripes
for (int stripe = drawStartX; stripe < drawEndX; stripe++)
{
int drawStart = -spriteSlices[stripe - drawStartX].Height / 2 + ScreenHeight / 2;
int drawEnd = spriteSlices[stripe - drawStartX].Height / 2 + ScreenHeight / 2;
double spriteDepth = spriteSlices[stripe - drawStartX].Depth;
//the conditions in the if are:
//1) it's in front of camera plane so you don't see things behind you
//2) it's on the screen (left)
//3) it's on the screen (right)
//4) ZBuffer, with perpendicular distance
if (spriteDepth > objectOffset && stripe > 0 && stripe < ScreenWidth && spriteDepth < WallSlices[stripe].Depth && transformY > objectOffset)
{
spriteBatch.Draw(
tex,
new Rectangle(stripe, drawStart, 1, drawEnd - drawStart),
new Rectangle(spriteSlices[stripe - drawStartX].TextureX, 0, 1, spriteSlices[stripe - drawStartX].Texture.Height),
Color.White);
}
}
}
