XNA - ReadPixels clears render buffer

Monkey Forums/Monkey Bug Reports/XNA - ReadPixels clears render buffer

pantson

(Posted 2015) [#1]

Hi

When ReadPixel is called, the render buffer is cleared, so nothing shows on screen that was drawn before the command is called.

I reported this in the following thread
http://www.monkey-x.com/Community/posts.php?topic=9462#98365
More findings can be found in that thread too

example
Hit left mouse button to switch between reading pixels and doing nothing. When reading pixels, the render buffer clears (no text on screen)

Strict 
Import mojo

Function Main:Int()
	New example()
	Return 0
End Function


Class example Extends App
	Field counter:Int
	Field grab:Int
	Field pixels:Int[10000]
	
	Method OnCreate:Int()
		counter=0
		grab = 0
		
		Return True
	End

	Method OnUpdate:Int()
		
		counter = counter + 1
		
		If MouseHit(MOUSE_LEFT)
			grab = 1 - grab
		End
		
		Return True
	End

	Method OnRender:Int()
		Cls 
		DrawText counter,20,20
		DrawText grab,20,40
		
		If grab=1
			' grab to tmp array
			ReadPixels(pixels,0,0,100,100)
		End
		Return True
	End
End

thanks for looking