2 replies to this topic

[Markolainen]

Update:
Since I didn't get the desired results with the fix ChaosMaker gave me in my game engine I thought I might try making square tiles which are 15x15 in size (so checks are always made from the exact center).
This didn't work either and some tiles are visible while the same tile but at the opposite x or y direction from the player is not.
Am I missing something or is the collision_line in GM a bit broken in this way?

Here is the example as well as code:

Spoiler

//Draw the LoS surface
draw_set_color(c_white);
draw_surface_ext(los_surface, 0, 0, cell_width, cell_height, 0, c_white, 1);

draw_sprite(spr_player, 0, x, y);

// Draws a line between the player and the cell where the mouse is pointing
if (!collision_line(x, y, floor(mouse_x/cell_width) * cell_width + 7, floor(mouse_y/cell_height) * cell_height + 7, obj_block, 1 , 1))
    draw_set_color(c_green);
else
    draw_set_color(c_red);
    
draw_line(x, y, floor(mouse_x/cell_width) * cell_width + 7, floor(mouse_y/cell_height) * cell_height + 7);

Example

Is there a good replacement for collision_line or does anybody have any other suggestions?

Old post:

Spoiler

I'm making a Rogue-like game and I'm using collision_line for FoW. But the problem is that it marks certain lines as collison free but the same line in the opposite y-direction as collisons even if I shift the y position on both the y1 and y2. The code seems to work along the x-axis better since the tiles are broader.

Here is the code and a file with the example:

// In the draw event of obj_player
draw_sprite(sprite_index, image_index, x,y);

if (y < mouse_y)
    yplus = -1;
else
    yplus = 0;

if (!collision_line(x, y + yplus, floor(mouse_x/16) * 16 + 8, floor(mouse_y/12) * 12 + 6 + yplus, obj_block, 0 , 1))
    draw_set_color(c_green);
else
    draw_set_color(c_red);
    
draw_line(x, y + yplus, floor(mouse_x/16) * 16 + 8, floor(mouse_y/12) * 12 + 6 + yplus);
draw_set_color(c_black);

The example

Does anybody have a solution for this problem or maybe an idea on a different approach?
I was thinking of adding all the blocks to a ds_grid and then through it make the collison checking with square tiles where the cells are an odd number wide & high (ex 31x31) but that seems like a lot of work and propably isn't the best idea.

Edited by Markolainen, 29 April 2012 - 01:34 PM.

[ChaosMaker]

solved

collision_line.gmk

[Markolainen]

solved

collision_line.gmk

Thanks!

I think it just felt natural changing both the y1 and the y2 but apparently I was wrong.
I still have issues with the horizontal & vertical tiles not being symmetrical but that's harder getting around without making invisible square blocks and check collision lines with them.