al_map_rgb()

al_map_rgb()

sai pavan boddu

Member #14,787

December 2012

Hello all,

I am going through the basic tutorials of allegro 5, so to change the display color there is function al_clear_to_display(), which takes the argument al_map_rgb(0,0,0).

In the Tutorial it is well explained that 0,0,0 are the values of RED, GREEN & BLUE . So in that case if we change r,g,b values we should have a change of colour in the display.

But that is not happening when I try with different values. The display remains Black irrespective of the values(r,g,b).

Any reason for this problem?

You can find the code at "http://wiki.allegro.cc/index.php?title=Allegro_5_Tutorial/Displays"

Thank you.

Thomas Fjellstrom

Member #476

June 2000

Have you flipped the display after clearing the screen?

--
Thomas Fjellstrom - [website] - [email] - [Allegro Wiki] - [Allegro TODO]
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Edgar Reynaldo

Major Reynaldo

May 2007

Quote:

al_clear_to_color(al_map_rgb(0,0,0));   al_flip_display();
al_rest(10.0);

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King Piccolo will make it so Then I could just flip it with some sweet, sweet matrix math. In either case, I’ll ride this wagon until the wheels fall off. Thanks to those that keep it running

Thomas Fjellstrom

Member #476

June 2000

Edgar: given he's changed it, there no guarantee that's still there.

pkrcel

Member #14,001

February 2012

With which values are you trying? those are int values ranging from 0 to 255.

just sayin'

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If one had the eternity of time, one would do things later. - Johan Halmén

sai pavan boddu

Member #14,787

December 2012

Edgar & Thomas : Yes I had flipped the dispaly

pkrcel : I gave inputs like (2,5,5)&(28,32,56)

Does that problem any thing to do with, static and dynamic linking?

LennyLen

Member #5,313

December 2004

Quote:

pkrcel : I gave inputs like (2,5,5)&(28,32,56)

The first set of values will give a colour that is most likely indistinguishable from black. The second set should definitely be noticeably different though.

sai pavan boddu said:

Does that problem any thing to do with, static and dynamic linking?

No.

Post the full final code that exhibits the problem.

sai pavan boddu

Member #14,787

December 2012

Oh! Brilliant , that worked for even higher values than what I mentioned .

Kris Asick

Member #1,424

July 2001

White = 255,255,255

Any values below 48 are going to be difficult to notice, especially if there's no comparison.

There's also floating-point versions of the map_rgb commands that take values from 0.0 to 1.0 instead of 0 to 255.

--- Kris Asick (Gemini)
--- http://www.pixelships.com

pkrcel

Member #14,001

February 2012

to me also the 2nd set of values gives a color VEEEERY close to black.

please try with something like magenta (255, 0, 255) and tell us what you get, please.

EDIT: missed that it was already sorted.....well CVD.

It is unlikely that Google shares your distaste for capitalism. - Derezo
If one had the eternity of time, one would do things later. - Johan Halmén

LennyLen

Member #5,313

December 2004

pkrcel said:

to me also the 2nd set of values gives a color VEEEERY close to black.

It could be your monitor settings. When I ran it, there was a console window behind that was black so the difference was pretty clear.

Arthur Kalliokoski

Second in Command

February 2005

{"name":"brightness_contrast_setting.png","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/a\/c\/ac68cc994b8fdb9bfabe20ad908132fc.png","w":720,"h":540,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/a\/c\/ac68cc994b8fdb9bfabe20ad908132fc"}

They all watch too much MSNBC... they get ideas.