From 6ca053f12638caeb805bf30032d43bcb1d8f2577 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sat, 28 Dec 2024 12:34:09 +0000
Subject: [PATCH] Use game coordinates for view and player positions

---
 app/main.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/app/main.c b/app/main.c
index 05973cb..977bec1 100644
--- a/app/main.c
+++ b/app/main.c
@@ -15,8 +15,8 @@
 #define SCALE 4
 
 #define TILESIZE 32
-#define VIEWWIDTH 8
-#define VIEWHEIGHT 6
+#define VIEWWIDTH (8 * TILESIZE)
+#define VIEWHEIGHT (6 * TILESIZE)
 
 #define MAX_PATH_LEN 128
 
@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
 	assert(0 == err);
 	window = SDL_CreateWindow(
 	    "2D Game", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
-	    SCALE * TILESIZE * VIEWWIDTH, SCALE * TILESIZE * VIEWHEIGHT, 0);
+	    SCALE * VIEWWIDTH, SCALE * VIEWHEIGHT, 0);
 	assert(NULL != window);
 	renderer = SDL_CreateRenderer(window, -1, 0);
 	assert(NULL != renderer);
@@ -161,10 +161,11 @@ int main(int argc, char *argv[])
 	pitex = IMG_LoadTexture(renderer, path);
 	assert(NULL != pitex);
 
-	int offx = 16, offy = 0;
+	// Initialize view and player
+	dvec_t vpos = { 512, 0 };
 	SDL_Rect psrc = { .y = 0, .w = PIWIDTH, .h = PIHEIGHT };
 	SDL_Rect pdest = { .w = SCALE * PIWIDTH, .h = SCALE * PIHEIGHT };
-	dvec_t pvel = { 0, 0 }, ppos = { 80, 80 };
+	dvec_t pvel = { 0, 0 }, ppos = { 640, 96 };
 
 	SDL_Event event;
 	uint64_t prevt = SDL_GetTicks64();
@@ -236,10 +237,15 @@ int main(int argc, char *argv[])
 		SDL_RenderClear(renderer);
 
 		// Draw map
-		for (int y = 0; y < VIEWHEIGHT; ++y) {
-			for (int x = 0; x < VIEWWIDTH; ++x) {
-				const unsigned tileid
-				    = map[x + offx + MAPSHIFTX][y + offy + MAPSHIFTY];
+		const int startx = TILESIZE * floor(vpos.x / TILESIZE);
+		const int starty = TILESIZE * floor(vpos.y / TILESIZE);
+		for (int y = starty; y < vpos.y + VIEWHEIGHT; y += TILESIZE) {
+			for (int x = startx; x < vpos.x + VIEWWIDTH; x += TILESIZE) {
+				const unsigned row = x / TILESIZE + MAPSHIFTX;
+				const unsigned col = y / TILESIZE + MAPSHIFTY;
+				if (row >= MAPWIDTH || col >= MAPHEIGHT)
+					continue;
+				const unsigned tileid = map[row][col];
 				if (0 == tileid)
 					continue;
 				const SDL_Rect src = {
@@ -249,8 +255,8 @@ int main(int argc, char *argv[])
 					.h = TILESIZE,
 				};
 				const SDL_Rect dest = {
-					.x = SCALE * TILESIZE * x,
-					.y = SCALE * TILESIZE * y,
+					.x = SCALE * (x - vpos.x),
+					.y = SCALE * (y - vpos.y),
 					.w = SCALE * TILESIZE,
 					.h = SCALE * TILESIZE,
 				};
@@ -261,8 +267,8 @@ int main(int argc, char *argv[])
 		// Draw player
 		const unsigned piframe = (t / BASEANIMPERIOD) % PIANIMLEN;
 		psrc.x = PIWIDTH * piframe;
-		pdest.x = SCALE * (int)ppos.x;
-		pdest.y = SCALE * (int)ppos.y;
+		pdest.x = SCALE * (int)(ppos.x - vpos.x);
+		pdest.y = SCALE * (int)(ppos.y - vpos.y);
 		SDL_RenderCopy(renderer, pitex, &psrc, &pdest);
 
 		SDL_RenderPresent(renderer);