From b292920b36adfbf79c56c2d4862017e006b99b52 Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Sat, 7 Mar 2026 09:02:32 +0100
Subject: [PATCH] rendering: wip viewport culling for map rendering.

- Added camera zoom rendering for tiles.
---
 src/r_assets.c     | 36 ++++++++++++++++--------------------
 src/r_render.c     | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 src/r_render.h     | 12 +++++++++++-
 src/t_camera.c     |  2 ++
 src/t_map.c        | 12 +++---------
 src/u_debug_font.h |  8 ++++----
 6 files changed, 81 insertions(+), 35 deletions(-)

diff --git a/src/r_assets.c b/src/r_assets.c
index 6c2f6aa..0943a47 100644
--- a/src/r_assets.c
+++ b/src/r_assets.c
@@ -52,29 +52,22 @@ void r_draw_solid_isometric_tile(i32 x, i32 y, r_color color) {
 	u32 j = 0;
 	r_color final_color;
 	u32 hover_color_shift = 0;
-	struct u_vec2 t = u_tile_to_screen(x, y);
-	struct u_vec2 tt = u_tile_to_screen(x+1, y+1);
-	struct u_vec2 tl = u_tile_to_screen(x+2, y);
-	struct u_vec2 tb = u_tile_to_screen(x+2, y-2);
+	struct t_camera *c = &t_main_camera;
+	i32 zoom_factor = t_camera_zoom_factor(c);
+	u32 tile_w = t_camera_zoom(c, R_TILE_W);
+	u32 tile_h = t_camera_zoom(c, R_TILE_H);
+	i32 zfx, zfy;
+
+	struct u_vec2 t = t_camera_zoom_vec2(c, u_tile_to_screen(x, y));
 
 	/* get mouse cursor and move by camera */
 	struct u_vec2 cursor_pos = u_world_to_camera(&t_main_camera, i_cursor_pos());
 	if (u_point_in_rect(cursor_pos.x, cursor_pos.y, 
 				t.x, t.y, 
-				R_TILE_W, R_TILE_H)) {
+				tile_w, tile_h)) {
 		hover_color_shift = 1;
 	}
-	
-	/* do not draw if tile is not visible at all
-	 * also include a few points outside the camera to avoid tiles
-	 * popping in
-	 */
-	if (!t_camera_is_visible_screen(&t_main_camera, t.x, t.y)
-			&& !t_camera_is_visible_screen(&t_main_camera, tt.x, tt.y)
-			&& !t_camera_is_visible_screen(&t_main_camera, tb.x, tb.y)
-			&& !t_camera_is_visible_screen(&t_main_camera, tl.x, tl.y)) {
-		return;
-	}
+
 	t = u_screen_to_camera(&t_main_camera, t);
 
 	/* converted origin point in isometric space */
@@ -82,9 +75,13 @@ void r_draw_solid_isometric_tile(i32 x, i32 y, r_color color) {
 	/* draw a tile texture from origin */
 	for (i = 0; i < R_TILE_W; i++) {
 		for (j = 0; j < R_TILE_H; j++) {
-			final_color = r_asset_fallback_tile[i + j * R_TILE_W] & color;
-			final_color <<= hover_color_shift;
-			r_draw_pixel(&r_framebuffer, t.x + i, t.y + j, final_color);
+			for (zfx = 0; zfx < zoom_factor; zfx++) {
+				for (zfy = 0; zfy < zoom_factor; zfy++) {
+					final_color = r_asset_fallback_tile[i + j * R_TILE_W] & color;
+					final_color <<= hover_color_shift;
+					r_draw_pixel(&r_framebuffer, t.x + zfx + i * zoom_factor, t.y + zfy + j * zoom_factor, final_color);
+				}
+			}
 
 		}
 	}
@@ -95,7 +92,6 @@ void r_draw_solid_isometric_tile(i32 x, i32 y, r_color color) {
 }
 
 void r_draw_tile(struct t_tile *t, i32 x, i32 y) {
-
 	switch (t->type) {
 		case T_TILE_TYPE_NONE:
 			break;
diff --git a/src/r_render.c b/src/r_render.c
index fcacfe8..bbf5e87 100644
--- a/src/r_render.c
+++ b/src/r_render.c
@@ -6,6 +6,7 @@
 #include "u_debug.h"
 
 struct r_framebuffer r_framebuffer;
+struct r_render_state  r_render_state;
 
 void r_draw_pixel(struct r_framebuffer *fb, i32 x, i32 y, r_color color) {
 	r_target_color *pixel = LRTS_NULL;
@@ -29,7 +30,7 @@ void r_draw_pixel(struct r_framebuffer *fb, i32 x, i32 y, r_color color) {
 void r_render_debug(void) {
 	struct lrts_state *state = lrts_state();
 
-	u_debug_draw_text(0, 0, "FPS: %02d, Tick: %d", state->fps, state->tick_count); 
+	u_debug_draw_text(0, 0, "FPS: %02d, Tick: %d, Frame: %d", state->fps, state->tick_count, state->frame_count); 
 }
 
 void r_render_frame(void) {
@@ -52,3 +53,46 @@ void r_render_frame(void) {
 	state->frame_count++;
 	state->fps = u_cap_fps();
 }
+
+void r_render_update_visible_tiles(void) {
+	i32 x, y;
+	struct u_vec2 t, tt, tl, tb;
+	struct t_camera *c = &t_main_camera;
+
+	r_render_state.start_tile.x = t_map.width;
+	r_render_state.start_tile.y = t_map.height;
+
+	for (x = 0; x < t_map.width; x++) {
+		for (y = 0; y < t_map.height; y++) {
+			t = t_camera_zoom_vec2(c, u_tile_to_screen(x, y));
+			tt = t_camera_zoom_vec2(c, u_tile_to_screen(x+1, y+1));
+			tl = t_camera_zoom_vec2(c, u_tile_to_screen(x+2, y));
+			tb = t_camera_zoom_vec2(c, u_tile_to_screen(x+2, y-2));
+
+			/* do not draw if tile is not visible at all
+			 * also include a few points outside the camera to avoid tiles
+			 * popping in
+			 */
+			if (t_camera_is_visible_screen(&t_main_camera, t.x, t.y)
+					|| t_camera_is_visible_screen(&t_main_camera, tt.x, tt.y)
+					|| t_camera_is_visible_screen(&t_main_camera, tb.x, tb.y)
+					|| t_camera_is_visible_screen(&t_main_camera, tl.x, tl.y)) {
+					
+					if (r_render_state.end_tile.x < x) {
+						r_render_state.end_tile.x = x;
+					}
+					if (r_render_state.end_tile.y < y) {
+						r_render_state.end_tile.y = y;
+					}
+
+					if (r_render_state.start_tile.x > x) {
+						r_render_state.start_tile.x = x;
+					}
+
+					if (r_render_state.start_tile.y > y) {
+						r_render_state.start_tile.y = y;
+					}
+			}
+		}
+	}
+}
diff --git a/src/r_render.h b/src/r_render.h
index c36390a..28fc9b0 100644
--- a/src/r_render.h
+++ b/src/r_render.h
@@ -13,15 +13,25 @@ struct r_framebuffer {
 	r_target_color *pixels;
 };
 
+struct r_render_state {
+	struct u_vec2 start_tile;
+	struct u_vec2 end_tile;
+};
+
 /* The global frame buffer. 
  * This needs to be initialized by the 
  * rendering platform
  */
 extern struct r_framebuffer r_framebuffer;
 
+extern struct r_render_state r_render_state;
+
 /* draws a singel pixel directly to a frame buffer */
 void r_draw_pixel(struct r_framebuffer *fb, i32 x, i32 y, r_color color);
 
-void r_render_frame();
+void r_render_frame(void);
+
+/* updats visible tiles based on the current camera position */
+void r_render_update_visible_tiles(void);
 
 #endif
diff --git a/src/t_camera.c b/src/t_camera.c
index 94dac55..57f5fd5 100644
--- a/src/t_camera.c
+++ b/src/t_camera.c
@@ -11,6 +11,7 @@ struct t_camera t_camera_init(i32 viewport_x, i32 viewport_y) {
 	c.viewport_y = viewport_y;
 
 	c.zoom = 1;
+	r_render_update_visible_tiles();
 
 	return c;
 }
@@ -21,6 +22,7 @@ void t_camera_scroll(struct t_camera *c, i32 by_x, i32 by_y) {
 	/* TODO: calculate min/max viewport based on map in a better way */
 	c->x += by_x;
 	c->y += by_y;
+	r_render_update_visible_tiles();
 }
 
 lrts_bool t_camera_is_visible_screen(struct t_camera *c, i32 x, i32 y) {
diff --git a/src/t_map.c b/src/t_map.c
index 55608a1..018ac29 100644
--- a/src/t_map.c
+++ b/src/t_map.c
@@ -17,20 +17,14 @@ struct t_map t_map_init(void) {
 			m.tiles[j * m.width + i].type = T_TILE_TYPE_GRASS;
 		}
 	}
-
+	r_render_update_visible_tiles();
 	return m;
 }
 
 void t_map_draw(struct t_map *m) {
 	i32 i, j;
-	struct u_vec2 start;
-	struct u_vec2 end;
-	
-	start.x = 0;
-	start.y = 0;
-
-	end.x = t_map.width;
-	end.y = t_map.height;
+	struct u_vec2 start = r_render_state.start_tile;
+	struct u_vec2 end = r_render_state.end_tile;
 
 	for (i = start.x; i < end.x; i++) {
 		for (j = start.y; j < end.y; j++) {
diff --git a/src/u_debug_font.h b/src/u_debug_font.h
index 4fd8fb7..04d8e08 100644
--- a/src/u_debug_font.h
+++ b/src/u_debug_font.h
@@ -25,13 +25,13 @@ const u8 u_debug_font[] = {
 	/* char 0x2a */
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
 	/* char 0x2b */
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+	0x00, 0x10, 0x10, 0x7c, 0x10, 0x10, 0x00, 0x00, 
 	/* char 0x2c */
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+	0x00, 0x00, 0x00, 0x00, 0x10, 0x30, 0x20, 0x00, 
 	/* char 0x2d */
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+	0x00, 0x00, 0x00, 0x7c, 0x00, 0x00, 0x00, 0x00, 
 	/* char 0x2e */
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x18, 0x18, 0x00, 
 	/* char 0x2f */
 	0x00, 0x08, 0x10, 0x10, 0x20, 0x20, 0x40, 0x40, 
 	/* char 0x30 */
-- 
2.30.2