Question about speed of drawing

[John Douma]

I am testing my drawing operations in Screen.jack using the supplied files in ScreenTest. As the test is running I see the objects being drawn. However, if I remove my copy of Screen.jack and just compile Main.jack so that the built-ins are used, the objects get drawn instantaneously. Should my code be that fast?

[cadet1620]

John Douma wrote

I am testing my drawing operations in Screen.jack using the supplied files in ScreenTest. As the test is running I see the objects being drawn. However, if I remove my copy of Screen.jack and just compile Main.jack so that the built-ins are used, the objects get drawn instantaneously. Should my code be that fast?

Mine works the same way.  I imagine that the VM Emulator's built in system functions are Java and that no VM interpretation is done to run them.  As an experiment you could copy TECS/tools/OS/Screen.vm into your ScreenTest directory to see how the authors' compiled Screen.jack VM code performs compared to yours.

--Mark

[John Douma]

I will try that. By the way, thanks a lot for all your replies. I am almost done. I only have the Keyboard and the Sys modules left.

[John]

Just in case anyone is looking at old entries I will make a suggestion.  My drawing of rectangles and circles was very slow also since I was drawing lines one pixel at a time.  Remember, though, that the bits in the memory map for a horizontal line will be in contiguous words.  When I went through the effort of changing my code so that for horizontal lines I fill in whole words (16 pixels) at a time with a single mask my drawing speed increased to the same as the provided Screen.vm.  The left and right edges of the lines have to be treated a bit different since the line may start and end in the middle of a word.  It takes a bit of coding, but really isn't that hard, and the change in speed is dramatic.