gervais's picture

Color format for UInteger

Hi
I am trying to use the function Color3 or Color4 with a UInteger but so far all I am getting is either a red color or a shade of red or black
It work find if I use the byte value directly but I can’t use the UInteger value properly

Dim lAlpha As Long = pbAlpha
miColor = Convert.ToUInt32((lAlpha * &H1000000) + (pbRed * &H10000) + (pbGreen * &H100) + pbBlue)

GL.Color4(miColor)


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the Fiddler's picture

Does VB.Net even support unsigned integers? If yes, you should be able to do something similar to this:

' Not tested, see below for a better solution
Dim color As UInteger = DirectCast(pbAlpha << 24, UInteger) Or DirectCast(pbRed << 16, UInteger) Or _
    DirectCast(pbGreen << 8, UInteger) Or DirectCast(pbBlue, UInteger)

However, I'd suggest taking advantage of the System.Drawing.Color class to improve clarity:

Dim color As Integer = Color.FromArgb(pbAlpha, pbRed, pbGreen, pbBlue).ToArgb()
GL.Color4(Color.FromArgb(pbAlpha, pbRed, pbGreen, pbBlue))

Edit: it seems that they added shift operators to VB.Net! The code a lot cleaner this way.

gervais's picture

I try all the combination you did suggest and the Direct Case do not like the conversion in VB and the color return a signed integer with a value of -1 if I try my old code the returned value is 4294967295 which is in hex "FFFFFFFF" which is the correct value but if a I use color4 with a unsigned integer with the correct value all it do is return me a shade of red like it only see the red value????

The ARGB values are all set to 255

it react only to the Alpha value if i turn the alpha value down the red color also go down

the Fiddler's picture

In two's complement arithmetic, (int32) '-1' has the same bit-pattern as (uint32) '4294967295': 'FFFF FFFF'.

Question: what are you trying to achieve?

In most cases, you should prefer the Color4 overloads that take 4 floats, 4 bytes or 1 System.Drawing.Color.

gervais's picture

I am testing what are the posibility and what is the format to use for creating texture manualy so that i can creat user inteface using image data and basicaly i was to see if i could use the old way of formating the color valu i was using for direct X

if i use 4 byte value with this function it work fine but with the unsigned intege it is no go

the Fiddler's picture

Ok, I think I've found the issue. You are using a method that takes a single UInteger, right? If this is true, then be warned that this method expects an *array* of 4 integers, i.e.:

Dim rgba as UInteger = New UInteger() { &Hffffffff, &Hffffffff, &Hffffffff, &Hffffffff }
GL.Color4(rgba(0));

Not intuitive, but this is how this method is defined.

In other words, always use the Color4 overloads that take 4 distinct parameters, i.e.:

GL.Color4(&Hffffffff, &Hffffffff, &Hffffffff, &Hffffffff)