Texture brightness for a 2D sprite

OpenGL Development
#21

No I was saying just draw the same one and alternate between trans and not trans.

#22

Wouldn’t that cause flickering o_O

1 frame is actually a pretty long time

#23

Why not just keep a white sprite texture separately and drawing it with glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA) and an alpha value at like, 0.5f? Would make any sprite brighter.
You could also do this with shaders, just do a texture lookup and discard the RGB components (only keeping alpha) and you just generated your white mask.
I think you’re really overcomplicating stuff. I would’ve just kept 2 different textures, one normal and one brighter one and then just switched between them, instead of trying to combine textures etc.

#24

The secondary colour extension can help you with this, Slick uses it for Image.drawFlash()


blic void drawFlash(float x,float y,float width,float height, Color col) {
                init();
                
                col.bind();
                texture.bind();

                if (GL.canSecondaryColor()) {
                        GL.glEnable(SGL.GL_COLOR_SUM_EXT);
                        GL.glSecondaryColor3ubEXT((byte)(col.r * 255), 
                                                                                                         (byte)(col.g * 255), 
                                                                                                         (byte)(col.b * 255));
                }
                
                GL.glTexEnvi(SGL.GL_TEXTURE_ENV, SGL.GL_TEXTURE_ENV_MODE, SGL.GL_MODULATE);

Kev

#25

Wow… if I knew it was this simple.

In our game, we are going to design “RenderEffects” that are somewhat similar to combat effects (poison, stun, etc.) but relate to visual modifications to the entity only. This seems like it’d be a great function to have in our render effect API, among other things. (grow, shrink, alpha mod, fade, show, spin, etc)

#26

Isn’t that the point? Go to 0:57 in this video, it was just the first classic brawler I thought of. Or this one, at 0.15, look for the guy on the right of the screen. Temporary flickering or fading is an incredibly common way of representing invincibility. That’s what I thought you were asking about.

But anyway, you’ve got your solution already. :slight_smile:

#27

Ah, my problem wasn’t related to alpha levels, it was related to how to increase the brightness or color intensity of the pixels so that they’re closer to white. (Brighter image). Thanks for the tip though :slight_smile: