png Alpha level

kuat · Post by **kuat** » Mon Mar 09, 2009 7:15 am

Hi there, it's my first post and i have a question.
Is there any way to improve graphics.h to make a funcion wich you can set the level of alpha transparency?

Let me explain:
I'm trying to port a little fade in and fade out Allegro funcion that uses "set_trans_blender" method, and the lib graphics.h does'nt any funcion like that...

Sorry About my very bad english... =x

ne0h · Post by **ne0h** » Wed Mar 11, 2009 6:49 am

Code: Select all

void XgeSetImageOpacity&#40;XgeImage* image, int opacity&#41;
&#123;
    int i;
    int size = image->TextureWidth * image->TextureHeight;
    XgeColor* data = image->data;
    for&#40;i = 0; i < size; i++, data++&#41;
        *data = *data + &#40;&#40;&#40;int&#41;&#40;&#40;float&#41;&#40;&#40;float&#41;0xFF / 100.00f&#41; * &#40;float&#41;opacity&#41; - A&#40;*data&#41;&#41; << 24&#41;;
&#125;

;)

Torch · Post by **Torch** » Wed Mar 11, 2009 5:15 pm

There is another formula that doesn't require so many float, should be faster.

kuat · Post by **kuat** » Thu Mar 12, 2009 9:47 pm

Thanx guys!

i'll try it later =D