Hello Graphics Programming and Theory, I figure you guys should be able to figure this out. For my project DOOM.Net I have multiple billboards throughout the level. Each THING(players, monsters, etc..) has an angle and a position(X and Y, DOOM levels are actually 2D), so I guess you could represent each thing as a 2D vector.
Now when the monster moves/rotates or the camera moves/rotates I need to figure out what frame(out of a sprite sheet) to draw. Here's some idea of how the sprite sheet looks and what values each angle has:
East is 0 degrees, north is 90, west is 180 and south is 270
This is the default shot. Both the camera and zombie guy there are facing north(90 degrees). In this shot I'm not actually trying to calculate the correct angle, I just render whatever frame the monsters angle equals( in this case 90 / 45 = 2 = North ).
I've tried a number of techniques. I tried taking the angle of the line between them, the difference between the zombie's angle and the player, both, but nothing seems it work right. Mabye my formulas are off or mabye I'm just going about it the wrong way.
Please help. The sooner this is fixed, the sooner I can add in the other cool monsters [smile].
