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Bitmap engine with slightly jerky movement, please help

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I have a 2d tile based bitmap engine up and running, but the bitmaps seem to move with a very small but still noticable jerk. It is definitley more appearent on diagonal movement. The change per frame is small (3-5 pixels per frame). I have thought about adjusting the velocities to keep a ratio with the screen (4:3 800*600). But I have a feeling it is something more detailed than this. Is there some basic rule of bitmap graphics I am missing here? Please help. [edited by - TomKazansky on December 2, 2002 11:40:30 PM]

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Is the FPS steady?

- Rob Loach
OverTech Technologies
-----------
"Life moves pretty fast. If you don''t stop and look around once in awhile, you could miss it."
- Ferris Bueller

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Yup the frame rate is locked.

I am using quite large tiles (128 * 128) for the background and the enemy bitmaps I am using are also rather large. Will this make any jerkiness more noticable?

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This is just a guess, but if you have lots of large bitmaps that don''t all fit in VRAM then doesn''t directx swap them in and out of VRAM as they''re needed. That would certainly slow things down. How much RAM does your video card have? How much RAM are you bitmaps taking up?

Cheers.

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Guest Anonymous Poster
Thank you I will check this out.

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To what is your framerate locked?
Is it synchronized with the screen refresh?
Having a sprite move at non-integer speeds also provides jerkyness. Think of a sprite which moves at 1.5p/f. It''s concurrent rounded x-values will be:
0.0 - 0
1.5 - 2
3.0 - 3
4.5 - 5
As you see, it''s movement is not linear.

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quote:
Original post by Prototype
Think of a sprite which moves at 1.5p/f. It''s concurrent rounded x-values will be:
0.0 - 0
1.5 - 2
3.0 - 3
4.5 - 5
As you see, it''s movement is not linear.



Do you mean:
0.0 - 0
1.5 - 1
3.0 - 2
4.5 - 3
etc?


- Rob Loach
OverTech Technologies
-----------
"Life moves pretty fast. If you don''t stop and look around once in awhile, you could miss it."
- Ferris Bueller

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OO! Wait a sec, your rounding the integers........ never mind, my mistake. I was quite confused.

- Rob Loach
OverTech Technologies
-----------
"Life moves pretty fast. If you don''t stop and look around once in awhile, you could miss it."
- Ferris Bueller

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