blitz-research
84 lines
2.5 KiB
HTML
84 lines
2.5 KiB
HTML
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<title>Blitz3D Docs</title>
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<link rel=stylesheet href=../css/commands.css type=text/css>
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<body>
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<h1>ReadPixel (x,y,[buffer])</h1>
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<h1>Parameters</h1>
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<table>
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<td>
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x - x coordinate of pixel
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y - y coordinate of pixel
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buffer (optional) - name of buffer to read colour value from, e.g. BackBuffer() (defaults to current graphics buffer)
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</td>
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</tr>
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<h1>Description</h1>
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Reads a color value from either the current buffer or the specified buffer.
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The returned colour value is in the form of an integer that contains the alpha, red, green and blue values of the pixel.
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You can use this command on a locked buffer for a slight speed-up. See LockBuffer.
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Warning: this is a low level command with no error checking for out of range parameters, use with care.
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See also: <a class=small href=GetColor.htm>GetColor</a>, <a class=small href=ReadPixelFast.htm>ReadPixelFast</a>.
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<h1><a href=../2d_examples/ReadPixel.bb>Example</a></h1>
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; ReadPixel/WritePixel Example
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; ----------------------------
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Graphics 640,480,16
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Print "Press a key to read color values (this may take a few seconds)"
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WaitKey()
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; Load and draw an image on to the screen - can be anything
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pic=LoadImage("media/blitz_pic.bmp")
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DrawImage pic,0,0
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; Initialise an array big enough to fit all the color information of the screen
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Dim pix(GraphicsWidth(),GraphicsHeight())
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; Use ReadPixel to get all the color information of the screen
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For y=0 To GraphicsHeight()
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For x=0 To GraphicsWidth()
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pix(x,y)=ReadPixel(x,y)
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Next
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Next
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Cls
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Locate 0,0
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Print "Press a key to write pixels (this may takes a few seconds)"
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Print "Once this has finished, you can then press a key to end the program"
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WaitKey()
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; Use WritePixel to redraw the screen using the color information we got earlier
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For y=0 To GraphicsHeight()
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For x=0 To GraphicsWidth()
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WritePixel x,y,pix(x,GraphicsHeight()-y) ; get y array value in backwards order, to flip screen
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Next
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Next
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WaitKey()
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</td>
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</tr>
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</table>
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<br>
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<a target=_top href=../index.htm>Index</a><br>
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<br>
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Click <a href=http://www.blitzbasic.co.nz/b3ddocs/command.php?name=ReadPixel&ref=comments target=_blank>here</a> to view the latest version of this page online</body>
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</html>
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