Subject: Re: [stella] JoustPong: maybe ditch "poorlords" wall From: Thomas Jentzsch <tjentzsch@xxxxxx> Date: Tue, 13 Jan 2004 19:30:10 +0100 |
On Tuesday, January 13, 2004 at 18:56, Glenn Saunders wrote: >>With factional speeds and some small sine/cosine tables that shouldn't >>be a problem anymore. > Could you explain how those tables would be used? The easy way: First you decide how many angles you want and what should be the ball speed. For each angle you need two values, one for the x- and one for the y-speed. Each values consists out of two bytes to store fractional speeds. E.g. the ball speed should be 3 pixel/frame, for an angle of 30° you get a speed of 1.5/2.6 (x/y) pixels/frame. Converted into fractional values you get 1/128 and 2/153. Then you need 4 RAM bytes for the ball, 2 bytes for x and y each (hi/low). In each frame you simply add the values from the table to the current values and use only the higher bytes for displaying the ball. The advanced way: Various optimizations are possible, e.g. the sine/cosine tables can overlap and you don't need the values for the whole circle. Have fun! Thomas _______________________________________________________ Thomas Jentzsch | *** Every bit is sacred ! *** tjentzsch at web dot de | ---------------------------------------------------------------------------------------------- Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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