Fading Images

A.Russell · Post by **A.Russell** » Sat Jan 28, 2006 3:44 pm

I want to fade an image.

I have tried changing the alpha value of the scolor variable with no luck. I tried this with both a 24 and 32 bit tga image with alpha channel (and also tried using a black and a white alpha). I cannot make the image transparent:

Code: Select all

		my_driver->draw2DImage(p_magic_book, core::position2d<s32>(screensize.Width/2-256, 25),
		core::rect<s32>(0,0, 512,700),0,video::SColor(255,255,255,changing_this_value_doesnt_do_anything), true);

Changing the values in the other channels is fine, just not the alpha. I have also set that last flag to both true and flase.

So, how to make an image transparent dynamically? (for fading in and out)

This might be a bug, because from the manual:

color,: Color with wich the image is colored. If the color equals Color(255,255,255,255), the color is ignored. Note that the alpha component is used: If alpha is other than 255, the image will be transparent.

I am using version 1.0

vitek · Post by **vitek** » Sat Jan 28, 2006 7:37 pm

Yes, it is a bug. I was able to fix it in the DX8 and 9 drivers by passing the correct value as the second parameter to setRenderStates2DMode. It looks like this was done so that compatibility could be maintained with the software renderers.

I believe the OpenGL driver is setting render states incorrectly in setRenderStates2DMode. If that was fixed, it could be made to work with the OpenGL driver also.

Travis

A.Russell · Post by **A.Russell** » Sun Jan 29, 2006 2:58 am

Thanks Travis,

I am using OpenGL as my prefered driver, so I will just have to wait for a bug fix.

Do the developers know about this?

Artenius · Post by **Artenius** » Mon Jan 30, 2006 10:46 pm

Maybe you could do as he did and use setRenderStates2DMode for DirectX. Maybe some 'for' looping decrementing the alpha value and you would have your fader.

Guest · Post by **Guest** » Tue Jan 31, 2006 9:10 am

i did a fading by drawing a 2D black rectangle which has alpha value.
i play over its alpha value, decrementing or incrementing it.
if you're interested, i can give you my class that i wrote

dhenton9000 · Post by **dhenton9000** » Tue Jan 31, 2006 11:01 am

Anonymous wrote:i did a fading by drawing a 2D black rectangle which has alpha value.
i play over its alpha value, decrementing or incrementing it.
if you're interested, i can give you my class that i wrote

I'd like to see that, can you post it somewhere? Thanks!!

Guest · Post by **Guest** » Mon Feb 06, 2006 1:41 pm

ok, sorry for the late, i've forget about it, i will post it there:
http://viper.sign.free.fr/transition.zip

but if you want to see this stuff, try
http://viper.sign.free.fr/rpgtest.zip

Guest · Post by **Guest** » Mon Feb 06, 2006 1:46 pm

i'll put the file on line when my little brother will turn on the computer, i'm at work now

Guest · Post by **Guest** » Mon Feb 06, 2006 1:55 pm

Sorry, having pb with my ftp so i put the files here:
http://viper.sign.free.Fr/Transition.cpp
and
http://viper.sign.free.Fr/Transition.h

for rpgtest:
left click = valid
right click = cancel
middle click can be used in the green land

to see the fading effect, go to the fire and left click, it should be ok

Guest · Post by **Guest** » Mon Feb 06, 2006 2:07 pm

i explain a little:

in an event, you use, the transitionObject->cover() or transitionObject->uncover() method.
in your display loop, you put transitionObject->render()

just analyze the code, there isn't be anything hard, i just draw a black panel and i play over its alpha value.

the difficultie is: when stop rendering, is the rendering finished and stuff like that.
for my game, i use this transition when i must go from a 'level' to another.