Pixel Collisions

/* Creator (and original version at): https://pastebin.com/u/ShaunJS */

//decimal fractions of hsp are stored in hsp_f
//every frame this fraction is added back in and the new fraction removed again
//this moves us in whole integers each frame that are still representative of decimal movement
//for example, at a hsp of 0.1 you would move 1 pixel every 10 frames.
//this resolves any issues of not detecting a collision at a fractional target (ie: no collision at 3.8, when there is at 4.0)
//which sometimes caused the player after rounding, to be drawn overlapping walls by 1 pixel.

hsp_final = hsp + hsp_f;
hsp_f = hsp_final - floor(abs(hsp_final))*sign(hsp_final);
hsp_final -= hsp_f;

vsp_final = vsp + vsp_f;
vsp_f = vsp_final - floor(abs(vsp_final))*sign(vsp_final);
vsp_final -= vsp_f;

//same old place_meeting collision code.
if (place_meeting(x+hsp_final,y,par_collide))
{
    var inc = sign(hsp_final);
    while (!place_meeting(x+inc,y,par_collide)) x+= inc;
    hsp_final = 0;
    hsp = 0;
}
x+=hsp_final;

if (place_meeting(x,y+vsp_final,par_collide))
{
    var inc = sign(vsp_final);
    while (!place_meeting(x,y+inc,par_collide)) y+= inc;
    vsp_final = 0;
    vsp = 0;
}
y+=vsp_final;