SegaRaycast/src/main.c

#include <genesis.h>

#define SPEED 2

Line l;

const u8 map[10][10] = {{1,1,1,1,1,1,1,1,1,1},
                	{1,0,0,0,0,0,0,0,0,1},
                	{1,1,1,1,0,0,1,1,1,1},
                	{1,0,0,1,0,0,1,0,0,1},
                	{1,0,0,0,0,0,1,0,0,1},
                	{1,0,0,1,0,0,1,1,0,1},
                	{1,1,1,1,0,0,1,0,0,1},
                	{1,0,0,0,0,0,0,0,0,1},
                	{1,0,0,0,0,0,1,0,0,1},
                	{1,1,1,1,1,1,1,1,1,1}};

void castRay(s16 angle){
  u8 r,mx,my,mp,dof;
  float rx,ry,ra,xo,yo;
  s16 ind = (int)((float)angle/360.0f*1024.0f);
  fix16 dx = sinFix16(ind);
  fix16 dy = cosFix16(ind);
  fix16 tan = fix16Div(dy, dx);
  fix16 aTan = fix16Div(-1, tan);
  s16 tanInt = fix16ToInt(fix16Mul(dx, 100));
  char str[10];
  sprintf(str, "%d", 10);
  BMP_drawText(str, 20, 0);
}

void mapscan(){

	u8 mapcolor = 12;
	mapcolor |= mapcolor << 4;
	int mapscale = 10;

	for(u8 x = 0; x < 10; x++){
		for(u8 y = 0; y < 10; y++){
			if(map[y][x] == 1){
				Vect2D_s16 mapverts[4] = {{x*mapscale,y*mapscale},{(x+1)*mapscale,y*mapscale},{(x+1)*mapscale,(y+1)*mapscale},{x*mapscale,(y+1)*mapscale}};
				BMP_drawPolygon(mapverts, 4, mapcolor);

			}		
		}

	}
}


void render(){
	//Clear the bitmap
	BMP_clear();

	//Draw the line defined above (in the background, hidden)
	BMP_drawLine(&l);

	mapscan();
  castRay(10);

	//Flip the data to the screen - i.e. actually draw the complete image on screen
	BMP_flip(1);

	//Increment the destination y coordinate
	l.pt2.y = l.pt2.y + 2;

	//Reset the destination y coordinate if it hits 160
	if (l.pt2.y == 160)
	{
	l.pt2.y = 0;
	}

  SYS_doVBlankProcess();

}

void update(){
  u16 joy = JOY_readJoypad(JOY_1);
  if(joy & BUTTON_LEFT) {
    l.pt1.x -= SPEED;
  }
  if(joy & BUTTON_RIGHT) {
    l.pt1.x += SPEED;
  }
  if(joy & BUTTON_UP) {
    l.pt1.y -= SPEED;
  }
  if(joy & BUTTON_DOWN) {
    l.pt1.y += SPEED;
  }
}

void initVDP(){
  SYS_disableInts();
  VDP_setPlaneSize(64,32,TRUE);
  SYS_enableInts();
}

int main()
{
  initVDP();

  //Initialise the bitmap engine
  BMP_init(FALSE, BG_A, PAL0, FALSE);

  //Set the colour of the line. We are using pallete 0 for the bitmap, so we have 0->15. 15 is used for white text, so we set an unused pallet colour, 14 to blue - RGB 0000FF.
  u16 colour_blue = RGB24_TO_VDPCOLOR(0x0000ff);
  u16 colour_red = RGB24_TO_VDPCOLOR(0x756a4a);
  PAL_setColor(14, colour_blue);
  PAL_setColor(13, colour_red);
  PAL_setColor(12, RGB24_TO_VDPCOLOR(0x00ff00));
  PAL_setColor(15, RGB24_TO_VDPCOLOR(0xff0000));
  VDP_setBackgroundColor(13);

  //A line needs a source coordinate x,y and a destination coordinate x,y along with a pallete colour.
  l.pt1.x = 15;
  l.pt1.y = 15;
  l.pt2.x = 255;
  l.pt2.y = 0;
  l.col = 14;
  l.col |= l.col << 4; // if we do not left shift the colour, we get gaps in the line

  while(TRUE)
  {
   	render();
    update();
  }
  return 0;
}