我使用两个位图,图像(子位图)和网格(主位图)
ALLEGRO_BITMAP* grid = NULL;
ALLEGRO_BITMAP* image = NULL;
ALLEGRO_DISPLAY* display = NULL;
//Initialization
display = al_create_display(SCREEN_W, SCREEN_H + INFO_H);
grid = al_create_bitmap(SCREEN_W, SCREEN_H + INFO_H);
al_set_target_bitmap(grid);
al_set_target_bitmap(al_get_backbuffer(display));
al_draw_bitmap(grid, 0, 0, 0);
//Creating a model
image = loadBitmapAtSize(...);
al_create_sub_bitmap(grid, 0, 0, columns, rows);
al_draw_bitmap(image, 0, 0, 0);
直到这里一切都进行得很好,但是如果我直接绘制到image(subbitmapt),那么我找不到如何将更改发送到显示的画面。
al_set_target_bitmap(image);
//rows and cols are the height and width of subbitmap
for (int y = 0; y < rows; ++y) {
for (int x = 0; x < columns; ++x) {
if(x == y || x-1 == y || x+1 == y || x == y-1 || x == y+1){
//I test the condition and the program is entering to the if
al_draw_pixel(x, y, al_map_rgb(255, 255, 255));
}
}
}
al_set_target_bitmap(grid);
al_flip_display();
任何想法在编辑子位图后如何更新主位图?
来自Allegro文档:
子位图是一种与先前存在的(父)位图共享绘图内存的位图,但是可能具有不同的大小和剪切设置。
https://www.allegro.cc/manual/5/al_create_sub_bitmap
[al_create_sub_bitmap
返回指向您需要分配给要使用的变量的ALLEGRO_BITMAP
的指针。
要创建和分配子位图,可以使用:
ALLEGRO_BITMAP* subbitmap = al_create_sub_bitmap(grid, 0, 0, columns, rows);
al_set_target_bitmap(subbitmap);
您必须将“网格”位图绘制到显示器上,然后翻转它。
al_set_target_backbuffer(display);
al_draw_bitmap(grid , 0 , 0 , 0);
al_flip_display();