tilemap rendering

examples/gsa_simple.c

@@ -8,9 +8,12 @@ void init() {
 	sprites[1].tile = 3;
 	sprites[1].x = 10;
 	sprites[1].y = 100;
+
+	maps[0].tiles[20][1] = 2;
 }
 
 void tick() {
 	sprites[0].x += 1;
 	sprites[1].x += 2;
+	maps[0].scrollx += 1;
 }

include/gsa.h

@@ -25,15 +25,24 @@
 #include "vec2i.h"
 #include "window.h"
 
+#define MAX_SPRITES 256
+#define TILEMAP_MAX_SIZE 1024
+#define MAX_TILEMAPS 4
+
 struct gsa_sprite {
 	u16 tile;
 	i32 x, y;
 };
 
-#define MAX_SPRITES 256
+struct gsa_map {
+	u16 tiles[TILEMAP_MAX_SIZE][TILEMAP_MAX_SIZE];
+	i32 w, h;
+	i32 scrollx, scrolly;
+};
 
 extern struct gsa_sprite sprites[MAX_SPRITES];
 extern struct sw_image8 *_gfx;
+extern struct gsa_map maps[MAX_TILEMAPS];
 
 int gsa_main(int argc, char *argv[]);
 

include/types.h

@@ -16,4 +16,7 @@ typedef i8 bool;
 #define true 1
 #define false 0
 
+i32 i32_max(i32 v1, i32 v2);
+i32 i32_min(i32 v1, i32 v2);
+
 #endif /* GUARD_649E63003BEAE79ECA2B813C4E131C9A */

meson.build

@@ -48,6 +48,7 @@ skunk_sources = [
 	'src/image8.c',
 	'src/shader.c',
 	'src/skunkworks.c',
+	'src/types.c',
 	'src/vec2i.c',
 	'src/window.c'
 ]

src/gsa.c

@@ -3,12 +3,14 @@
 #include "gl.h"
 #include "image8.h"
 #include "shader.h"
+#include "types.h"
 #include <gl/gl.h>
 #include <string.h>
 #define GSA_NOMAIN
 #include "gsa.h"
 
 struct gsa_sprite sprites[256];
+struct gsa_map maps[MAX_TILEMAPS];
 
 struct sw_image8 *_gfx;
 struct sw_window *_win;
@@ -159,12 +161,36 @@ static void update_palette_gl() {
 }
 
 void _gsa_tick() {
-	i32 i;
+	i32 i, x, y, startx, starty, endx, endy;
 
 	tick();
 
 	next_render_vert = 0;
-	/* glBegin(GL_TRIANGLES); */
+
+	for(i = 0; i < MAX_TILEMAPS; ++i) {
+		startx = maps[i].scrollx / 16;
+		starty = maps[i].scrolly / 16;
+		endx = i32_min(TILEMAP_MAX_SIZE, startx + 20);
+		endy = i32_min(TILEMAP_MAX_SIZE, starty + 12);
+		startx = i32_max(0, startx);
+		starty = i32_max(0, starty);
+
+		for(x = startx; x <= endx; ++x) {
+			for(y = starty; y <= endy; ++y) {
+				u16 tile = maps[i].tiles[x][y];
+				if(tile) {
+					rect(
+					    x * 16 - maps[i].scrollx,
+					    y * 16 - maps[i].scrolly,
+					    16,
+					    16,
+					    tile
+					);
+				}
+			}
+		}
+	}
+
 	for(i = 0; i < MAX_SPRITES; ++i) {
 		if(sprites[i].tile > 0) {
 			rect(sprites[i].x, sprites[i].y, 16, 16, sprites[i].tile);

src/types.c

@@ -0,0 +1,9 @@
+#include "types.h"
+
+i32 i32_max(i32 v1, i32 v2) {
+	return v1 > v2 ? v1 : v2;
+}
+
+i32 i32_min(i32 v1, i32 v2) {
+	return v1 < v2 ? v1 : v2;
+}