From 8574f9d0f0f6ed9ce66bb590873dc7bc2253fb1f Mon Sep 17 00:00:00 2001
From: Samuel Walker <swalker@piwalker.net>
Date: Fri, 30 Aug 2024 12:12:20 -0600
Subject: [PATCH] raytracing almost working

---
 src/main.c | 117 ++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 97 insertions(+), 20 deletions(-)

diff --git a/src/main.c b/src/main.c
index e7df3db..38e6e0e 100644
--- a/src/main.c
+++ b/src/main.c
@@ -16,36 +16,109 @@ const u8 map[10][10] = {{1,1,1,1,1,1,1,1,1,1},
                 	{1,0,0,0,0,0,1,0,0,1},
                 	{1,1,1,1,1,1,1,1,1,1}};
 
+int dist(int ax, int ay, int bx, int by){
+  return (ax-bx)*(ax-bx) + (ay-by)*(ay-by);
+}
+
 void castRay(s16 angle){
-  u8 r,mx,my,mp,dof;
+
+  u16 r,mx,my,mp,dof;
   fix16 rx,ry,ra,xo,yo;
   s16 ind = (int)((float)angle/360.0f*1024.0f);
+
   fix16 dy = sinFix16(ind);
   fix16 dx = cosFix16(ind);
-  fix16 tan = fix16Div(dy, dx);
-  fix16 aTan = fix16Div(FIX16(-1), tan);
+  fix16 tan = FIX16(1);
+  if(dx != 0) tan = fix16Div(dy, dx);
+  fix16 aTan = FIX16(0);
+  if(tan != 0) aTan = fix16Div(FIX16(-1), tan);
   s16 tanInt = fix16ToInt(fix16Mul(aTan, FIX16(100)));
   dof = 0;
-  if(angle > 180) {
-    ry = FIX16(l.pt1.y / 10);
-    rx = fix16Add(fix16Mul(fix16Sub(FIX16(l.pt1.y), ry),aTan),FIX16(l.pt1.x));
-    yo = FIX16(-10);
-    xo = fix16Mul(fix16Neg(yo),aTan);
-  }
-  if(angle < 180) {
-    ry = FIX16((l.pt1.y / 10)+10);
-    rx = fix16Add(fix16Mul(fix16Sub(FIX16(l.pt1.y), ry),aTan),FIX16(l.pt1.x));
-    yo = FIX16(10);
-    xo = fix16Mul(fix16Neg(yo),aTan);
-  }
+  fix16 distH = FIX16(500);
+  fix16 hx = FIX16(l.pt1.x);
+  fix16 hy = FIX16(l.pt1.y);
   if(angle == 0 || angle == 180){
     rx = FIX16(l.pt1.x);
     ry = FIX16(l.pt1.y);
     dof = 8;
+  }else {
+    if(angle > 180) {
+      ry = FIX16(l.pt1.y / 10 * 10)-FIX16(1);
+      rx = fix16Mul(FIX16(l.pt1.y) - ry,aTan) + FIX16(l.pt1.x);
+      yo = FIX16(-10);
+      xo = fix16Mul(0-yo,aTan);
+    }
+    if(angle < 180) {
+      ry = FIX16((l.pt1.y / 10 * 10)+10);
+      rx = fix16Mul(FIX16(l.pt1.y) - ry,aTan) + FIX16(l.pt1.x);
+      yo = FIX16(10);
+      xo = fix16Mul(0-yo,aTan);
+    }
+  }
+  while(dof<8){
+    mx = fix16ToInt(rx) / 10;
+    my = fix16ToInt(ry) / 10;
+    if(mx >=0 && my >= 0 && mx < 10 && my < 10 && map[my][mx] == 1){
+      dof = 8;
+      hx = rx;
+      hy = ry;
+      distH = dist(l.pt1.x, l.pt1.y, fix16ToInt(rx), fix16ToInt(ry));
+    }else{
+      rx = rx + xo;
+      ry = ry + yo;
+      dof += 1;
+    }
+  }
+
+  dof = 0;
+  fix16 distV = FIX16(500);
+  fix16 vx = FIX16(l.pt1.x);
+  fix16 vy = FIX16(l.pt1.y);
+  float nTan = 0-tan;
+  if(angle > 90 && r < 270) {
+    rx = FIX16(l.pt1.x / 10 * 10)-FIX16(1);
+    ry = fix16Mul(FIX16(l.pt1.x) - rx,nTan) + FIX16(l.pt1.y);
+    xo = FIX16(-10);
+    yo = fix16Mul(0-xo,nTan);
+  }
+  if(angle < 90 || angle > 270) {
+    rx = FIX16((l.pt1.x / 10 * 10)+10);
+    ry = fix16Mul(FIX16(l.pt1.x) - rx,nTan) + FIX16(l.pt1.y);
+    xo = FIX16(10);
+    yo = fix16Mul(0-xo,nTan);
+  }
+  if(angle == 90 || angle == 270){
+    rx = FIX16(l.pt1.x);
+    ry = FIX16(l.pt1.y);
+    dof = 8;
   }
   while(dof<8){
-    
+    mx = fix16ToInt(rx) / 10;
+    my = fix16ToInt(ry) / 10;
+    if(mx >=0 && my >= 0 && mx < 10 && my < 10 && map[my][mx] == 1){
+      dof = 8;
+      vx = rx;
+      vy = ry;
+      distV = dist(l.pt1.x, l.pt1.y, fix16ToInt(rx), fix16ToInt(ry));
+    }else{
+      rx = rx + xo;
+      ry = ry + yo;
+      dof += 1;
+    }
   }
+  if(distV < distH){
+    l.pt2.x = fix16ToInt(vx);
+    l.pt2.y = fix16ToInt(vy);
+  }else {
+    l.pt2.x = fix16ToInt(hx);
+    l.pt2.y = fix16ToInt(hy);
+  }
+  char* str[5];
+  sprintf(str, "%d", distV);
+  BMP_drawText(str, 20, 0);
+  char* str2[5];
+  sprintf(str2, "%d", distH);
+  BMP_drawText(str2, 20, 1);
 }
 
 void mapscan(){
@@ -72,10 +145,12 @@ void render(){
 	BMP_clear();
 
 	//Draw the line defined above (in the background, hidden)
-	BMP_drawLine(&l);
 
 	mapscan();
-  castRay(286);
+  if(angle > 360) angle = 0;
+  if(angle < 0) angle = 359;
+  castRay(angle);
+  BMP_drawLine(&l);
 
 	//Flip the data to the screen - i.e. actually draw the complete image on screen
 	BMP_flip(1);
@@ -96,10 +171,12 @@ void render(){
 void update(){
   u16 joy = JOY_readJoypad(JOY_1);
   if(joy & BUTTON_LEFT) {
-    l.pt1.x -= SPEED;
+    //l.pt1.x -= SPEED;
+    angle--;
   }
   if(joy & BUTTON_RIGHT) {
-    l.pt1.x += SPEED;
+    //l.pt1.x += SPEED;
+    angle++;
   }
   if(joy & BUTTON_UP) {
     l.pt1.y -= SPEED;