Additive Blending - how?

jack_1313 · Post by **jack_1313** » Tue Jan 13, 2004 11:09 am

How does one use additive blending (as opposed to standard alpha blending)? I hear that DirectX calls can be made through the ‘driver’ – but while setting the render state appropriately would work perfectly when drawing additional primitives into the scene, the majority of objects (such as meshes, billboards etc) are rendered with a single call to drawAll(). Can I set a material to use additive blending?

jack_1313 · Post by **jack_1313** » Fri Jan 16, 2004 12:23 am

Several days and no replies to such a straightforward question?

niko · Post by **niko** » Fri Jan 16, 2004 7:52 am

Hm, maybe EMT_TRANSPARENT_ADD_COLOR is what you need? If not, simply add your own material to the driver.

tstuefe · Post by **tstuefe** » Sat Jan 17, 2004 7:13 am

You probably will have to code it via plain DirectX APIs.

For DirectX 9, set the following Render States (with IDirect3DDevice9::SetRenderState):

D3DRS_SRCBLEND=D3DBLEND_ONE
D3DRS_DESTBLEND=D3DBLEND_ONE
D3DRS_ALPHABLENDENABLE=TRUE

Should result in additive Blending.

DX8.1 should be similar. See the DirectX Documentation.

No clue how to do this with OpenGL, can anyone fill in?