From what I've read, the renderer design shouldn't make any assumption of which rendering techniques will be used so theoretically it should be possible to do forward/deferred rendering cascaded shadow mapping, whatever.
This is a separate issue -- your renderer should be constructed in a few tiers/layers. The lower layer deals with abstracting resources, states, commands, across platforms. On top of this layer, you should be able to implement any kind of rendering technique. The game developer should be able to make use of this layer if they need
to, but will by default use a higher level layer.
The game's specific 'high level' renderer is built upon the lower layer, and this is where specific rendering techniques and pipelines will be implemented.
Regardless of whether the higher-level is data-driven or not, it should still have a clear separation from the lower-level (i.e. this level might be hard-coded in C++, or might be described with XML, whatever
The problem is how will something like cascaded shadow mapping be defined in simple data? The view frustum has to be slipt, matrices updated and all (visible) scene objects drawn for each cascade...
This is rather complex to defined in xml or whatever format is used... Or is a scripting language used to program this? And the renderer is called data-driven because it uses scripts instead of native code?
IMHO, if you don't have to recompile the EXE/DLL/etc to make a change, then it's "data driven"... so this definition includes scripts.
N.B. Lua in particular is often used as a data description language, as well as a general scripting language -- many lua files just contain tables of information and no code, which makes it almost the same as JSON/XML/etc. This kind of Lua code is definitely "data".
As for describing complex rendering pipelines in data, here's the "concept art" from my engine's data-driven render pipeline viewer:
Dashed & rounded boxes are objects beloning to the game, which it has "exported" to the data-driven renderer by name.
The solid & rounded boxes are temporary data buffers generated during the pipeline -- e.g. the frustum culling function generates an array of indices of visible models.
The Dashed rectangle named "Render" is a named entry-point into the data-driven file, called by the game.
Solid rectangles are hard-coded functions that have been exported to the data-driven renderer.
The yellow plugs on top are the function arguments -- e.g. "Draw Models" takes a pool of model instances, an array of indices into that pool and a render-target to draw to (Camera should also be plugged into "Draw Models" as an input, but it's missing on this diagram...
The yellow plugs below are the function return values -- "Draw Models" returns the render-target that it drew to.
The dashed green plugs show the inferred flow of control when this graph is compiled into a linear sequence of commands.
The large grey box denotes a data-driven function, made up of a "sub-graph", which you can see inside of (a bloom post-process effect
The above diagram could be represented in XML, Lua, hard-coded C++, text, etc... as it's just a big bag of nodes and links.
Another cool feature of this is that you can actually inspect the pipeline data and determine your Render-Target pool requirements. e.g. the above pipe requires maximum of 1 "standard
" target and 2 "1/4th standard
" targets at any one time. As you add more complex post-process stages, the tools can automatically tell you what the minimum RT pool requirements are, and can try different ways of linearizing the graph to maximize resource sharing.
Edited by Hodgman, 21 August 2012 - 10:34 PM.