Sprites and Displaybitmap

Havie · 09 December 2018, 23:33

I have a screen that is 640x400 and I am using Displaybitmap to scroll around using the mouse. My problem is that my main character is a sprite and it seems that sprite coordinates are independent of screen coordinates as when I change the x and y offset of the screen to scroll around, the sprite doesn't move!

Any suggestions?

P.S. Works ok if I blit a shape but would rather use a sprite!

Daedalus · 10 December 2018, 18:46

Yep, that's normal. Sprites are an entirely different layer of the display to the bitmap, so operate completely independently. The sprite coordinates are always relative to the actual display, regardless of what's being displayed. To have them match the scrolling, you'll need to offset them by the scroll position. So, if your bitmap view is (25,60), your sprite position will be (spritex-25, spritey-60). This means you will have to update the sprite positions at the same time as you update the bitmap position, otherwise you it won't look right.

Havie · 10 December 2018, 20:36

Yes - have thought about this over night and guess this would be the answer (a part of me was hoping there might be some 'magic' solution which would mean that I don't have to add the offsets to all the sprites

So, if I'm right and you use a dual playfield with sprites then technically there are 3 layers?

Daedalus · 10 December 2018, 22:53

Yep - and some games even use sprites to create a third layer of parallax. On AGA especially, you can cover the entire width and height of the screen with 5 sprites so it's a nice option.

Shatterhand · 12 December 2018, 14:46

[ Show youtube player ]

This was done on Blitz Basic, and I don't think I'll ever make anything out of it.

This is a way to make a nice parallax with "animated" backgrounds using sprites and dual playfield. The main character is also made of two 3 colors sprites...

The Amiga Hardware is interesting because there are many different ways you can approach coding your game. It's interesting but also a bit complicated as you usually have to plan well ahead before writing any line of code

09 December 2018, 23:33	#1
Havie Registered User Join Date: Mar 2012 Location: UK Posts: 1,894	Sprites and Displaybitmap I have a screen that is 640x400 and I am using Displaybitmap to scroll around using the mouse. My problem is that my main character is a sprite and it seems that sprite coordinates are independent of screen coordinates as when I change the x and y offset of the screen to scroll around, the sprite doesn't move! Any suggestions? P.S. Works ok if I blit a shape but would rather use a sprite!

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10 December 2018, 18:46	#2
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,341	Yep, that's normal. Sprites are an entirely different layer of the display to the bitmap, so operate completely independently. The sprite coordinates are always relative to the actual display, regardless of what's being displayed. To have them match the scrolling, you'll need to offset them by the scroll position. So, if your bitmap view is (25,60), your sprite position will be (spritex-25, spritey-60). This means you will have to update the sprite positions at the same time as you update the bitmap position, otherwise you it won't look right.

10 December 2018, 20:36	#3
Havie Registered User Join Date: Mar 2012 Location: UK Posts: 1,894	Yes - have thought about this over night and guess this would be the answer (a part of me was hoping there might be some 'magic' solution which would mean that I don't have to add the offsets to all the sprites So, if I'm right and you use a dual playfield with sprites then technically there are 3 layers?

10 December 2018, 22:53	#4
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,341	Yep - and some games even use sprites to create a third layer of parallax. On AGA especially, you can cover the entire width and height of the screen with 5 sprites so it's a nice option.

12 December 2018, 14:46	#5
Shatterhand Warhasneverbeensomuchfun Join Date: Jun 2001 Location: Rio de Janeiro / Brazil Age: 41 Posts: 3,450	[ Show youtube player ] This was done on Blitz Basic, and I don't think I'll ever make anything out of it. This is a way to make a nice parallax with "animated" backgrounds using sprites and dual playfield. The main character is also made of two 3 colors sprites... The Amiga Hardware is interesting because there are many different ways you can approach coding your game. It's interesting but also a bit complicated as you usually have to plan well ahead before writing any line of code

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