some of the tutorials that try to explain using timers to lock game unit speeds propose this: player.x += player.x_units_per_second * frame_time. x is the new pixel location after a frame update, frame_time is the time transpired between start of frame and end of frame, and will be extremely tiny for simple scenes and on fast cpus. This leads to my question: how the heck do I render a 0.00245 pixel increase along the x-y axis? Do I prevent my player-render function from executing until a certain amount of time has passed, say 0.2 seconds...? I''m stumped. Hope I explained things clear enough.. thanks, muffin

You don''t. You internally calculate your sub-pixel coordinates,
and when you are ready to blt it to the screen, you cast them to integers.

You could also do it like this:

Instead of drawing a theoretically infinite amount of frames per second (like quake games) just have a definite maximum of 30 frames per second. Then you know what speed the unit will move at "normal" speed.

(anything over 30 frames can''t be detected by the human eye I thought i heard somewhere)

To get a frames per second value just check how much time was
"left over" at each draw and add it all together to see how many frames *could have* been drawn.


For me anyway, in my 2D world, this is much easier. (i know that it is probably totally wrong though)


wise_guy

see, here is the perfect example of a need for fixed point integers, (as mentioned by anonymous...)

here is one way to do this....

    // setup a global define to store the accuracy of our numbers...#define MAP_POINT_ACCURACY     1000LONG GetScrnPoint(LONG virtual_pnt){     return (virtual_pnt / MAP_POINT_ACCURACY);}LONG GetMapPoint(LONG scrn_pnt){     return (scrn_pnt * MAP_POINT_ACCURACY);}    

so you store the map coords as a point * MAP_POINT_ACCURACY, this way you can adjust coords less than 1 scrn pixel.
when you want to do a screen draw, simply use the GetScrnPoint() function to get the "real pixel" location of the sprite/object.

hope this helps...

http://www.ill-lusion.com

thanks a bunch all! Now I just have to retool all my ints to floats...



cheers,
muffin

float x;float y;void draw_loop(){  x += dicimalAmount;  y += decimalAmount;  drawToScreen((int)x, (int) y);} 

"Now go away or I shall taunt you a second time"
- Monty Python and the Holy Grail