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Nasu is chr spritesheet editor.

Nasu is a spritesheet editor created to help design and assemble assets for Famicom games. It can import and export into the .chr format.

The application was initially created to help us with the porting of Donsol to the Famicom, and was later made available for everyone to use. It has since evolved to include the features of the drawing software Noodle. It is currently used to create both Famicom projects such as spacetime, and the 1bit illustrations of the Neauismetica.

Nasu was the first in a series of image creation tools, exploring the concept of Small Sharp Tools for graphical tasks, and was designed to be compatible with Moogle.

nasu.c

To control the window size and default colors, edit the values defined at the top of the file itself. Press , E to export a .chr file, press R to render a .bmp file, and press h to toggle tile guides. To learn more, visit the repository.

sudo apt-get install libsdl2-dev

The following code is a single-file implementation written in 450 lines of ANSI C, the only dependecy is SDL2.

cc -std=c89 -Wall nasu.c -L/usr/local/lib -lSDL2 -o nasu
#include <SDL2/SDL.h>
#include <stdio.h>

#define HOR 32
#define VER 16
#define PAD 8
#define ZOOM 2
#define color1 0x000000
#define color2 0x72DEC2
#define color3 0xFFFFFF
#define color4 0x444444
#define color0 0x111111

#define SZ (HOR * VER * 16)

typedef struct Brush {
	int x, y;
	int px, py;
	int mode;
	int size;
	int color;
	int down;
	int edit;
	int erase;
} Brush;

char* modes[] = {
    "line",
    "tone",
    "bold",
    "full",
    "hori",
    "veri",
    "exes",
    "fixe"};

unsigned char chrbuf[SZ];
int colors[] = {color1, color2, color3, color4, color0};
int WIDTH = 8 * HOR + PAD * 2;
int HEIGHT = 8 * VER + PAD * 2;
int FPS = 30;
int GUIDES = 0;
SDL_Window* gWindow = NULL;
SDL_Renderer* gRenderer = NULL;
SDL_Texture* gTexture = NULL;
uint32_t* pixels;

/* helpers */

int
distance(int ax, int ay, int bx, int by)
{
	return (bx - ax) * (bx - ax) + (by - ay) * (by - ay);
}

int
spos(char* s, char* ss)
{
	int a = 0, b = 0;
	while(s[a] != '\0') {
		if(s[a] == ss[b]) {
			if(ss[b + 1] == '\0')
				return a - b;
			b++;
		} else
			b = 0;
		a++;
	}
	return -1;
}

int
getclr(int r, int g, int b)
{
	return r && g && b && r == g && g == b ? 1 : r > g && r > b ? 2 : g > r && g > b ? 3 : 0;
}

/* chr */

int
rowchr(int x, int y)
{
	return (y % 8) + ((x / 8 + y / 8 * HOR) * 16);
}

int
getchr(int x, int y)
{
	int ch1, ch2;
	int r = rowchr(x, y);
	int px = x % 8;
	if(r < 0 || r > SZ - 8)
		return 0;
	ch1 = (chrbuf[r] >> (7 - px)) & 1;
	ch2 = (chrbuf[r + 8] >> (7 - px)) & 1;
	return ch1 && !ch2 ? 1 : !ch1 && ch2 ? 2 : ch1 && ch2 ? 3 : 0;
}

void
putchr(int x, int y, int color)
{
	int r = rowchr(x, y);
	int px = x % 8;
	if(x < 0 || y < 0 || x > 8 * HOR || y > 8 * VER || r > SZ - 8)
		return;
	if(color == 0) {
		chrbuf[r] &= ~(1UL << (7 - px));
		chrbuf[r + 8] &= ~(1UL << (7 - px));
	} else if(color == 2) {
		chrbuf[r] |= 1UL << (7 - px);
		chrbuf[r + 8] &= ~(1UL << (7 - px));
	} else if(color == 1) {
		chrbuf[r] &= ~(1UL << (7 - px));
		chrbuf[r + 8] |= 1UL << (7 - px);
	} else if(color == 3) {
		chrbuf[r] |= 1UL << (7 - px);
		chrbuf[r + 8] |= 1UL << (7 - px);
	}
}

void
newchr(void)
{
	int i;
	for(i = 0; i < SZ; ++i)
		chrbuf[i] = 0x00;
}

int
jagg(int x, int y)
{
	int n = getchr(x, y + 1);
	int e = getchr(x + 1, y);
	int s = getchr(x, y - 1);
	int w = getchr(x - 1, y);
	int h = getchr(x, y);
	if(h == n && h == e && h != s && h != w)
		return 1;
	if(h == e && h == s && h != w && h != n)
		return 1;
	if(h == s && h == w && h != n && h != e)
		return 1;
	if(h == w && h == n && h != e && h != s)
		return 1;
	return 0;
}

int
patt(int x, int y, int mode, int size)
{
	if(mode == 1)
		return ((x + y) % 4) == 0 && ((y - x) % 4) == 0;
	if(mode == 2)
		return ((x + y) % 2) == 0 && ((y - x) % 2) == 0;
	if(mode == 3)
		return 1;
	if(mode == 4)
		return y % size == 0;
	if(mode == 5)
		return x % size == 0;
	if(mode == 6)
		return (x + y) % size == 0 || (x - y) % size == 0;
	return 0;
}

void
fill(int x, int y, int mode, int size, int color)
{
	int ox, oy;
	for(ox = x - (size / 2); ox < x + size; ++ox)
		for(oy = y - (size / 2); oy < y + size; ++oy)
			if(mode == 7 && jagg(ox, oy))
				putchr(ox, oy, 0);
			else if(patt(ox, oy, mode, size) && distance(x, y, ox, oy) < size)
				putchr(ox, oy, color);
}

void
line(int ax, int ay, int bx, int by, int color)
{
	int dx = abs(bx - ax), sx = ax < bx ? 1 : -1;
	int dy = -abs(by - ay), sy = ay < by ? 1 : -1;
	int err = dx + dy, e2;
	for(;;) {
		putchr(ax, ay, color);
		if(ax == bx && ay == by)
			break;
		e2 = 2 * err;
		if(e2 >= dy) {
			err += dy;
			ax += sx;
		}
		if(e2 <= dx) {
			err += dx;
			ay += sy;
		}
	}
}

/* draw */

void
draw(uint32_t* dst)
{
	int b, i, j, id = 0;
	for(b = 0; b < SZ; b += 16)
		for(i = 0; i < 8; i++)
			for(j = 7; j >= 0; j--) {
				int ch1 = chrbuf[b + i];
				int ch2 = chrbuf[b + i + 8];
				int color = ((ch1 >> j) & 0x1) + (((ch2 >> j) & 0x1) << 1);
				int ti = id / 64;
				int odd = (ti + (ti / HOR + 2)) % 2 == 0;
				int px = (ti / (HOR * VER)) * (8 * HOR) + (ti % HOR) * 8 + (id % 8);
				int py = ((ti / HOR) * 8) + ((id % 64) / 8);
				dst[(py + PAD) * WIDTH + (px + PAD)] = colors[GUIDES && odd && color == 0 ? 4 : color];
				id++;
			}
	SDL_UpdateTexture(gTexture, NULL, dst, WIDTH * sizeof(uint32_t));
	SDL_RenderClear(gRenderer);
	SDL_RenderCopy(gRenderer, gTexture, NULL, NULL);
	SDL_RenderPresent(gRenderer);
}

void
update(Brush* b)
{
	if(b->edit)
		SDL_SetWindowTitle(gWindow, "Nasu*");
	else
		SDL_SetWindowTitle(gWindow, "Nasu");
	printf("%s %d:%d [%d:%dx%d]\n",
	       modes[b->mode],
	       b->size,
	       b->color,
	       HOR,
	       VER,
	       ZOOM);
}

/* options */

int
error(char* msg, const char* err)
{
	printf("Error %s: %s\n", msg, err);
	return 0;
}

void
loadchr(char* path)
{
	FILE* f = fopen(path, "rb");
	if(f == NULL)
		error("Load", "Invalid input file");
	if(!fread(chrbuf, sizeof(chrbuf), 1, f))
		error("Load", "Invalid input size");
	fclose(f);
}

void
loadbmp(char* path)
{
	FILE* f = fopen(path, "rb");
	int i, width = HOR * 8, height = VER * 8, size = 3 * width * height;
	unsigned char header[54];
	unsigned char data[4096 * 256];
	if(!fread(header, sizeof(unsigned char), 54, f))
		error("Load", "Invalid bmp header");
	if(!fread(data, sizeof(unsigned char), size, f))
		error("Load", "Invalid bmp body");
	for(i = 0; i < size; i += 3)
		putchr((i / 3) % width, height - (i / 3) / width - 1,
		       getclr(data[i + 2], data[i + 1], data[i]));
	fclose(f);
}

void
tochr(Brush* b)
{
	FILE* f = fopen("nasu-export.chr", "wb");
	if(!fwrite(chrbuf, sizeof(chrbuf), 1, f))
		error("Save", "Invalid output file");
	fclose(f);
	b->edit = 0;
}

void
tobmp(void)
{
	SDL_Surface* surface = SDL_GetWindowSurface(gWindow);
	GUIDES = 0;
	draw(pixels);
	SDL_RenderReadPixels(gRenderer,
	                     NULL,
	                     SDL_PIXELFORMAT_ARGB8888,
	                     surface->pixels,
	                     surface->pitch);
	SDL_SaveBMP(surface, "nasu-render.bmp");
	SDL_FreeSurface(surface);
}

void
quit(void)
{
	free(pixels);
	SDL_DestroyTexture(gTexture);
	gTexture = NULL;
	SDL_DestroyRenderer(gRenderer);
	gRenderer = NULL;
	SDL_DestroyWindow(gWindow);
	gWindow = NULL;
	SDL_Quit();
	exit(0);
}

void
domouse(SDL_Event* event, Brush* b)
{
	switch(event->type) {
	case SDL_MOUSEBUTTONUP:
		if(event->button.button == SDL_BUTTON_LEFT) {
			b->down = 0;
			b->px = 0;
			b->py = 0;
		}
		if(event->button.button == SDL_BUTTON_RIGHT)
			b->erase = 0;
		b->edit = 1;
		update(b);
		break;
	case SDL_MOUSEBUTTONDOWN:
		if(event->button.button == SDL_BUTTON_LEFT)
			b->down = 1;
		if(event->button.button == SDL_BUTTON_RIGHT)
			b->erase = 1;
		if(event->button.button == SDL_BUTTON_MIDDLE) {
			b->erase = 0;
			if(b->px != 0 && b->py != 0) {
				b->x = (event->motion.x - (PAD * ZOOM)) / ZOOM;
				b->y = (event->motion.y - (PAD * ZOOM)) / ZOOM;
				line(b->px, b->py, b->x, b->y, b->erase ? 0 : b->color);
				draw(pixels);
			}
		}
		b->px = (event->motion.x - (PAD * ZOOM)) / ZOOM;
		b->py = (event->motion.y - (PAD * ZOOM)) / ZOOM;
		break;
	case SDL_MOUSEMOTION:
		if(b->down) {
			b->x = (event->motion.x - (PAD * ZOOM)) / ZOOM;
			b->y = (event->motion.y - (PAD * ZOOM)) / ZOOM;
			if(b->mode == 0)
				line(b->px, b->py, b->x, b->y, b->erase ? 0 : b->color);
			else
				fill(b->x, b->y, b->mode, b->size, b->erase ? 0 : b->color);
			draw(pixels);
			b->px = b->x;
			b->py = b->y;
		}
		break;
	}
}

void
dokey(SDL_Event* event, Brush* b)
{
	switch(event->key.keysym.sym) {
	case SDLK_ESCAPE:
		quit();
		break;
	case SDLK_e:
		tochr(b);
		break;
	case SDLK_r:
		tobmp();
		break;
	case SDLK_TAB:
		b->color = b->color > 2 ? 0 : b->color + 1;
		break;
	case SDLK_h:
		GUIDES = !GUIDES;
		draw(pixels);
		break;
	case SDLK_n:
		newchr();
		draw(pixels);
		break;
	case SDLK_BACKQUOTE:
		b->mode = 7;
		break;
	case SDLK_1:
		b->mode = 0;
		break;
	case SDLK_2:
		b->mode = 1;
		break;
	case SDLK_3:
		b->mode = 2;
		break;
	case SDLK_4:
		b->mode = 3;
		break;
	case SDLK_5:
		b->mode = 4;
		break;
	case SDLK_6:
		b->mode = 5;
		break;
	case SDLK_7:
		b->mode = 6;
		break;
	case SDLK_z:
		if(b->size > 1)
			b->size -= 1;
		break;
	case SDLK_x:
		if(b->size < 30)
			b->size += 1;
		break;
	}
	update(b);
}

int
init(void)
{
	int i, j;
	if(SDL_Init(SDL_INIT_VIDEO) < 0)
		return error("Init", SDL_GetError());
	gWindow = SDL_CreateWindow("Nasu",
	                           SDL_WINDOWPOS_UNDEFINED,
	                           SDL_WINDOWPOS_UNDEFINED,
	                           WIDTH * ZOOM,
	                           HEIGHT * ZOOM,
	                           SDL_WINDOW_SHOWN);
	if(gWindow == NULL)
		return error("Window", SDL_GetError());
	gRenderer = SDL_CreateRenderer(gWindow, -1, 0);
	if(gRenderer == NULL)
		return error("Renderer", SDL_GetError());
	gTexture = SDL_CreateTexture(gRenderer,
	                             SDL_PIXELFORMAT_ARGB8888,
	                             SDL_TEXTUREACCESS_STATIC,
	                             WIDTH,
	                             HEIGHT);
	if(gTexture == NULL)
		return error("Texture", SDL_GetError());
	pixels = (uint32_t*)malloc(WIDTH * HEIGHT * sizeof(uint32_t));
	if(pixels == NULL)
		return error("Pixels", "Failed to allocate memory");
	for(i = 0; i < HEIGHT; i++)
		for(j = 0; j < WIDTH; j++)
			pixels[i * WIDTH + j] = color1;
	return 1;
}

int
main(int argc, char** argv)
{
	int ticknext = 0;
	Brush brush;
	brush.down = 0;
	brush.color = 1;
	brush.edit = 0;
	brush.size = 10;
	brush.mode = 2;

	if(!init())
		return error("Init", "Failure");

	if(argc > 1 && spos(argv[1], ".bmp") > -1)
		loadbmp(argv[1]);
	else if(argc > 1 && spos(argv[1], ".chr") > -1)
		loadchr(argv[1]);
	else
		newchr();

	draw(pixels);
	update(&brush);

	while(1) {
		int tick = SDL_GetTicks();
		SDL_Event event;
		if(tick < ticknext)
			SDL_Delay(ticknext - tick);
		ticknext = tick + (1000 / FPS);
		while(SDL_PollEvent(&event) != 0) {
			if(event.type == SDL_QUIT)
				quit();
			else if(event.type == SDL_MOUSEBUTTONUP ||
			        event.type == SDL_MOUSEBUTTONDOWN ||
			        event.type == SDL_MOUSEMOTION) {
				domouse(&event, &brush);
			} else if(event.type == SDL_KEYDOWN)
				dokey(&event, &brush);
			else if(event.type == SDL_WINDOWEVENT)
				if(event.window.event == SDL_WINDOWEVENT_EXPOSED)
					draw(pixels);
		}
	}
	quit();
	return 0;
}
— Found a mistake? Submit an edit to nasu.c.txt(504 lines)

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Last update on 20T05, edited 25 times. +113/159fh-----+