ImagesCollide2 and DrawSubImageRect Images?

BlitzMax Forums/BlitzMax Programming/ImagesCollide2 and DrawSubImageRect Images?

therevills

(Posted 2016) [#1]

Hi All,

I'm using image atlases by using DrawSubImageRect, but I've just tried to use ImagesCollide2 on them and of course it doesnt work on how I want it to work :)

Any ideas on a solution to use ImageCollide2 and image atlases?

Cheers,
Steve

Derron

(Posted 2016) [#2]

either write your own check... pixel based should be similary fast/alow... or hold a timage of each sprite in the memory.

of course the first option geta trickier if you allow rotation and scaling.

Bye
Ron

Kryzon

(Posted 2016) [#3]

To expand on the 'your own check' idea, if you look at the source of Max2D.bmx the pixel-collision code uses a quad that represents an image.
I think it's possible to make another function that creates that same quad object out of a subsection of the image, then proceed to use that quad normally to check collisions with the built-in code.
So you would be testing collision with the same sub-rectangle that you are drawing with your atlases.

You should be able to do that by modifying copies of the functions ImagesCollide2, CollideImage and CreateQuads. The latter is the one where you would create a TQuad to represent a subsection of the image, but it might be more complicated than that.
The other functions of the collision system that were not mentioned above shouldn't need changes.

https://github.com/blitz-research/blitzmax/blob/master/mod/brl.mod/max2d.mod/max2d.bmx#L1160

therevills

(Posted 2016) [#4]

Thanks guys, I'll have a look at altering max2d :)

skidracer

(Posted 2016) [#5]

Hmm, I am not sure you will even need to alter max2d.

If you make your own copy of code in max2d.bmx[1483]

Function CreateQuad:TQuad(image:TImage,frame,x#,y#,w#,h#,id:Object)

and add a pixmap argument, which if not null you could use instead of the images pixmap to set the quads mask member

Then you could keep a pixmapwindow object with your sub rectangle shapes that represents the cell on the atlas and pass that in (it would be better not to create one each time).

Derron

(Posted 2016) [#6]

Of course, even simpler would be to switch to using plain DrawImage of cells created with LoadImage(pixmapwindow) for your atlas stuff, it is simpler and just as optimal as DrawImageRect.

Hmppf... that is indeed a smart approach ...

... and I am still using the rect-variant based on the idea to save texture switches to improve performance.

While pixmapwindow-variant is "virtual", LoadImage() is not using the reference but creating a kind of pixmap-copy / texture. (when manipulating the original image, the "window"-referencing-image is not updated)

If LoadImage would work with references, the following example should show similar "image portions" after hitting "space".

SuperStrict

Graphics 800,600

Local image:TImage = CreateImage(256,256, PF_RGBA8888)
local px:TPixmap = LockImage(image)
For local x:int = 0 until px.width
	For local y:int = 0 until px.height
		px.WritePixel(x,y, Int(255 * $1000000) + Int(x * $10000) + Int(y * $100) + Int(255))
	Next
Next


local myPix:TPixmap = PixmapWindow(LockImage(image), 0,0, 64,64)
local myImage:TImage= LoadImage( myPix )


While True
	If KeyHit(KEY_SPACE)
		local px:TPixmap = LockImage(image)
		For local x:int = 0 until 64
			For local y:int = 0 until 64
				px.WritePixel(x,y, Int(255 * $1000000) + Int(x*4 * $10000) + Int(y * $100) + Int(x*4))
			Next
		Next
	endif
				


	Cls
	Select PollEvent()
		Case EVENT_WINDOWCLOSE, EVENT_APPTERMINATE
			EndGraphics()
			End
	EndSelect

	if KeyHit(KEY_ESCAPE) then End

	'tile test
	'TileImage(myImage,0,0)


	DrawImage(Image, 0, 0)

	DrawImage(myImage, MouseX(), MouseY())
	DrawPixmap(myPix, MouseX(), MouseY() + 74)

	DrawText("image", MouseX(), MouseY())
	DrawText("pixmap", MouseX(), MouseY() + 74)

	Flip
Wend


EndGraphics
End

bye
Ron

skidracer

(Posted 2016) [#7]

Oops, my bad.

I know better now thanks Ron.

Derron

(Posted 2016) [#8]

I would lke to get your approach working as it would allow things like tileimage for referenced image portions ...for now you can only use loops and draw it x/y times.
Would save me some code in my sprite-type.

PS: my post above wasn't meant offending.

Bye
Ron