xormod/xormod.c

#include "font.h"
#include "EGA8x8.h"
#include "platform.h"

#include <stdio.h>
#include <SDL.h>

#define SWAP(a, b) ({ \
    __typeof(a) tmp = (a); \
    (a) = (b); \
    (b) = tmp; \
})

typedef struct {
    int x1;
    int y1;
    int x2;
    int y2;
    int w;
    int h;
    int s;
    SDL_Surface *surface;
    SDL_Texture *texture;
    uint32_t *pixels;
    uint32_t color;
} Picture;

static void Picture_render(Picture *p, SDL_Renderer *rend);
static Picture *Picture_new(SDL_Renderer *rend,
    int x, int y, int w, int h, uint32_t color) {
    
    Picture *p = calloc(1, sizeof(Picture));

    p->x1 = x;
    p->x2 = x + w;
    p->y1 = y;
    p->y2 = y + h;
    p->w = w;
    p->h = h;
    p->color = color;
    p->s = (w + 7) / 8 * 8;

    p->pixels = malloc(p->s * h * sizeof(uint32_t));
    p->surface = SDL_CreateRGBSurfaceWithFormatFrom(
        p->pixels, w, h, 32, p->s * sizeof(uint32_t),
        SDL_PIXELFORMAT_RGBA32);

    Picture_render(p, rend);
    return p;
}

typedef uint32_t uint32_8 __attribute__ ((vector_size (8 * sizeof(uint32_t))));

static void Picture_render(Picture *p, SDL_Renderer *rend) {
    int w = p->w, h = p->h;
    uint32_8 c = p->color - (uint32_8){};
    uint32_8 y = p->y1 - (uint32_8){};
    for (int j = 0, r = 0; j < h; j++, y += 1) {
        uint32_8 x = p->x1 + (uint32_8){0, 1, 2, 3, 4, 5, 6, 7};
        for (int i = 0; i < w; i += 8,r += 8, x += 8) {
            uint32_8 z = (x ^ y) % 9;
            uint32_8 f = (z==0) & c;
            memcpy(&p->pixels[r], (uint32_t*)&f, sizeof(f));
        }
    }
    if (p->texture) SDL_DestroyTexture(p->texture);
    p->texture = SDL_CreateTextureFromSurface(rend, p->surface);
    SDL_SetTextureBlendMode(p->texture, SDL_BLENDMODE_NONE);
}

static void Picture_move(Picture *p, int x, int y) {
    p->x1 += x;
    p->x2 += x;
    p->y1 += y;
    p->y2 += y;
}

struct int2 { int x; int y; };

typedef struct {
    union {
        struct {
            Picture *tl;
            Picture *tr;
            Picture *bl;
            Picture *br;
        };
        Picture *pics[4];
    };
    struct int2 offset;
} Field;

void Field_init(Field *f, SDL_Renderer *rend, int w, int h) {
    f->tl = Picture_new(rend, 0, 0, w, h, 0xff7fffff);
    f->tr = Picture_new(rend, w, 0, w, h, 0xffff7fff);
    f->bl = Picture_new(rend, 0, h, w, h, 0xffffff7f);
    f->br = Picture_new(rend, w, h, w, h, 0xff7fff7f);
    f->offset = (struct int2){ 0,  0 };
}

void Field_scroll(Field *f, SDL_Renderer *rend) {
    int w = f->pics[0]->w;
    int h = f->pics[0]->h;
    if (f->offset.y < f->tl->y1) {
        SWAP(f->tl, f->bl);
        SWAP(f->tr, f->br);
        Picture_move(f->tl, 0, -2*h);
        Picture_move(f->tr, 0, -2*h);
        Picture_render(f->tl, rend);
        Picture_render(f->tr, rend);
    }
    if (f->offset.x < f->tl->x1) {
        SWAP(f->tl, f->tr);
        SWAP(f->bl, f->br);
        Picture_move(f->tl, -2*w, 0);
        Picture_move(f->bl, -2*w, 0);
        Picture_render(f->tl, rend);
        Picture_render(f->bl, rend);
    }
    if (f->offset.y > f->br->y1) {
        SWAP(f->tl, f->bl);
        SWAP(f->tr, f->br);
        Picture_move(f->bl, 0, 2*h);
        Picture_move(f->br, 0, 2*h);
        Picture_render(f->bl, rend);
        Picture_render(f->br, rend);
    }
    if (f->offset.x > f->br->x1) {
        SWAP(f->tl, f->tr);
        SWAP(f->bl, f->br);
        Picture_move(f->tr, 2*w, 0);
        Picture_move(f->br, 2*w, 0);
        Picture_render(f->tr, rend);
        Picture_render(f->br, rend);
    }
}

void Field_draw(Field *f, SDL_Renderer *rend) {
    for (int i = 0; i < 4; i++) {
        Picture *p = f->pics[i];
        SDL_Rect dst = {
            p->x1 - f->offset.x, p->y1 - f->offset.y, p->w, p->h,
        };
        SDL_RenderCopy(rend, p->texture, NULL, &dst);
    }
}

int main() {

    int w = 1280, h = 720;

    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        fprintf(stderr, "Can't init: %s\n", SDL_GetError());
        return -1;
    }

    SDL_Window *window = SDL_CreateWindow("xormod",
        SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, w, h,
        ACCEL_PLATFORM | SDL_WINDOW_FULLSCREEN);
    if (window == NULL) {
        fprintf(stderr, "Can't open window: %s\n", SDL_GetError());
        return -1;
    }

    SDL_GetWindowSize(window, &w, &h);

    SDL_Renderer *rend = SDL_CreateRenderer(window, -1,
        SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);

    SDL_Texture *font = load_font(rend);

    Field f;
    Field_init(&f, rend, w, h);

    struct int2 mouse_prev = { -1, -1 };
    int running = 1;
    while (running) {
        const uint8_t *keys = SDL_GetKeyboardState(NULL);
        if (keys[SDL_SCANCODE_ESCAPE] || keys[SDL_SCANCODE_Q]) {
            break;
        }
        if (keys[SDL_SCANCODE_LEFT]) {
            f.offset.x -= 16;
        }
        if (keys[SDL_SCANCODE_RIGHT]) {
            f.offset.x += 16;
        }
        if (keys[SDL_SCANCODE_UP]) {
            f.offset.y -= 16;
        }
        if (keys[SDL_SCANCODE_DOWN]) {
            f.offset.y += 16;
        }
        
        struct int2 mouse;
        if (SDL_GetMouseState(&mouse.x, &mouse.y) & SDL_BUTTON(SDL_BUTTON_LEFT)) {
            if (mouse_prev.x != -1 ) {
                f.offset.x -= mouse.x - mouse_prev.x;
                f.offset.y -= mouse.y - mouse_prev.y;
            }
            mouse_prev = mouse;
        } else if (mouse_prev.x != -1) {
            mouse_prev = (struct int2) { -1, -1 };
        }

        Field_scroll(&f, rend);
        Field_draw(&f, rend);

        char buf[72];
        SDL_SetRenderDrawColor(rend, 0, 0, 0, 255);
        SDL_RenderFillRect(rend, &(SDL_Rect) {
            0, 0, sizeof(buf)*font_w, 8*font_h
        });

        draw_text(rend, font, ACCEL_PLATFORM_STR, sizeof(ACCEL_PLATFORM_STR), RC(1,1), 255, 255, 255);

        size_t len = snprintf(buf, sizeof(buf),
            "off.x: %d, off.y: %d", f.offset.x, f.offset.y);
        draw_text(rend, font, buf, len, RC(2, 1), 255, 255, 255);

        char *q[] = {"TL", "TR", "BL", "BR"};
        for (int i = 0; i < 4; i++) {
            Picture *p = f.pics[i];
            len = snprintf(buf, sizeof(buf), "%s| x1: %05d, x2: %05d, y1: %05d, y2: %05d, p: %p",
                q[i], p->x1, p->x2, p->y1, p->y2, p);
            draw_text(rend, font, buf, len, RC(3+i, 1), 255, 255, 255);
        }

        SDL_RenderPresent(rend);

        SDL_Event e;
        while (SDL_PollEvent(&e)) {
            if (e.type == SDL_QUIT) {
                running = 0;
            }
        }
    }

    SDL_DestroyRenderer(rend);
    SDL_DestroyWindow(window);
    SDL_Quit();

    return 0;
}