Alpha Channel help

[ShadowOfintent]

So i've just started using the irrlicht engine i have managed to get get alpha channels working BUT i have run into a problem.

its not on the plane that i want it to be instead it creates a whole new sprite at the camera node start point



i am using the alpha code:
// Alpha Channels

node = smgr->addBillboardSceneNode(node, core::dimension2d<f32>(50, 50));
node->setMaterialFlag(video::EMF_LIGHTING, true);
node->setMaterialType(video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF);
node->setMaterialTexture(0, driver->getTexture("textures/factory/crane_pipe.tga"));

[JP]

I haven't the first clue at what you're even trying to achieve

Tell us what the picture should look like...

[ShadowOfintent]

haha fair enough WELL

the grate you see right. it should be alpha but instead its created a spirte in the background that is alpha of the same texture and i got no idea why.

[rogerborg]

Reeeeally not following you here. Any chance you could post some code, and explain (ideally with inline comments) what you expect it to do?

[JP]

I think maybe you're not understanding how the engine works or something... The code you showed i would expect to create something similar to the alpha'd grate in the distance...

How is the non-alpha's grate created? is it part of the map geometry? Or is it a seperate model you've loaded? It's clearly not a billboard so it seems you've misunderstood something!

[bitplane]

Code: Select all

        node = smgr->addBillboardSceneNode(node, core::dimension2d<f32>(50, 50));

That's why it adds another sprite, because you're adding a billboard sprite to the scene.

You need to find the mesh buffer with this texture and set its material type.

Code: Select all

ITexture *tex = driver->getTexture("textures/factory/crane_pipe.tga");

// loop through materials in this node
for (u32 i=0; i < levelNode->getMaterialCount(); ++i)
{
    // get the material
    SMaterial &mat = levelNode->getMaterial(i);

    // if the diffuse texture is the grate then make it transparent
    if (mat.TextureLayer[0].Texture == tex)
       mat.MaterialType = EMT_TRANSPARENT_ALPHA_CHANNEL_REF;
}

Not guaranteed to work because I didn't compile it, but in future you should read and understand each line of code instead of just copying and pasting it and guessing at what it does. Go through the examples, they're not that hard!

[ShadowOfintent]

i made the model with GTKRadiant

and want the grate to be transparent i have tried the code posted by bitplane
and it still dosnt work =\

[ShadowOfintent]

K. So i got it but now the box is to small i dont need the plane in GTK anymore but this is what i get