CODEWITHSUNDEEP
c
2013Asker
2013Asker

Reputation: 2058

How to convert screen coordinates to world coordinates for simple 2D game?

I started using this solution, but then I noticed it doesn't map correctly when the character is at a coordinate with remainder.

First I get the visible range from the camera. Then I get the mouse position and divide by the block size, here's the problem: I'm assuming there's a whole block at the start of the screen, but in reality there could be 1/4, 2/4 and 3/4 of a block, the same goes for the end of the screen.

How can I correctly perform this conversion in the most efficient manner?

typedef struct {
    float x, y;
} Point;

Point camera_screen_coord_to_game(Camera *camera, int x, int y)
{
    Range range = camera_get_visible(camera, game_clock_ticks());
    int block_size = settings_get_block_size();
    Point game_coord;

    game_coord.x = range.x0 + x / block_size;
    game_coord.y = range.y1 - 1 - y / block_size;

    return game_coord;
}

Upvotes: 1

Views: 496

Answers (1)

Bgie
Bgie

Reputation: 513

Could it be because x, y and block_size are all ints? cast them to float before dividing, and you get the fractional part.

Upvotes: 1

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