multi-pass rendering?

Quote:

Original post by Endar Am a close or really way off?

Close :-)

I'm not really up to speed on vertex and pixel shaders (my primary interests are elsewhere), but as far as fixed-function goes you basically have multi-pass and multitexture. Different aspects of a surface (texture, lightmap, decals, etc.) can be rendered in multiple passes, or in some cases combined into single multitexture passes. This is how Quake 3-style graphics were implemented, so as you can see you can get a lot of mileage out of these techniques. I don't know if or how that's changed with the advent of pixel and vertex shaders, but I'm sure others can tell you all about that.

You may need multiple passes to render one effect depending on the target hardware. On my GeForce 2, I only have 2 texture units so I need 2 passes to do simple bump mapping. If I want an ambient map and a reflection map, it is one more pass. To add stencil shadows, as I don't have the two side stencil extension, I have to add one Z pass and 2 passes for front and back faces. Now, I added a glow effect that need one more pass in a smaller resolution... with a modern hardware, you can do all this in just a few passes...

Uh, okay.

Is the whole multi pass thing run from the dev's code? Or is it done automatically API side?

I mean, just say I have a function 'render' for my scene graph that calls 'render' for each object. If I want multi pass, am I going to have to call that more that once a frame, but say if I wanted to have reflections, would I call 'render' once with the stencil buffer disabled, and then once with the stencil buffer enabled to draw the reflections?