ReadPixel64

ReadPixel64 〔BlitzLLVM〕

Command Index · BlitzBasic · Buffers and Pixels

ReadPixel64:Int64 x:Int32, y:Int32, buffer:Int32=0, Out red:Float16=0, Out green:Float16=0, Out blue:Float16=0, Out alpha:Float16=0

Parameter	Mode	Type	Default	Description
x	In	Int32	required	Horizontal position of the pixel.
y	In	Int32	required	Vertical position of the pixel.
buffer	In	Int32	0	The buffer to read from. Defaults to the current buffer.
red	Out	Float16	0	Variable of type Float16 that gets the red of the pixel, from 0 to 1. Can be left out.
green	Out	Float16	0	Variable of type Float16 that gets the green of the pixel, from 0 to 1. Can be left out.
blue	Out	Float16	0	Variable of type Float16 that gets the blue of the pixel, from 0 to 1. Can be left out.
alpha	Out	Float16	0	Variable of type Float16 that gets the alpha of the pixel, from 0 to 1. Can be left out.

Returns: The pixel as the buffer stores it, 8 bytes with the first byte in the lowest bits (for the depth 64 that is the red, green, blue and alpha half floats), or 0 if the position is outside of the buffer.

Description

〔BlitzLLVM〕 This command does not exist in the original Blitz products. BlitzLLVM adds it.

Returns the color of a pixel of a buffer as a Long. The color has 16 bits for each of alpha, red, green and blue from the top ($AAAARRRRGGGGBBBB), whatever the buffer is made of, so nothing is lost in a buffer that Graphics3D made with the depth 64, see Color depth. A buffer with 8 bits per channel gives each of them times 257 ($FF is $FFFF), and one with 10 bits fills the lower bits from the upper ones. This is a BlitzLLVM extension: the originals have no buffers with more than 8 bits per channel. Reads the color of a pixel as half precision floats (Float16) into the variables that are given, and returns the pixel as the buffer stores it. A buffer made with the depth 64 stores half floats, so the channels are exactly what is stored, even above 1; for the other depths they are the value from 0 to 1 that the stored bits mean. This is a BlitzLLVM extension.

Differences

• The color is not turned into an integer: the channels are Float16, and the returned number is the memory of the pixel (8 bytes for the depth 64, the 4 bytes of the stored word for the others). See Color depth.

Examples

Graphics3D 320, 240, 64, 2
SetBuffer BackBuffer()
Cls
WritePixel64 10, 10, 0, 0.5, 0.25, 2.0, 1.0
Local r:Float16, g:Float16, b:Float16, a:Float16
Local c:Long = ReadPixel64(10, 10, 0, r, g, b, a)
Print "red " + r + ", green " + g + ", blue " + b + ", alpha " + a
WaitKey

Related Commands

ReadPixel, ReadPixelFast, ReadPixelFast64 〔BlitzLLVM〕, WritePixel64 〔BlitzLLVM〕

Command Index · BlitzBasic · Buffers and Pixels