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multiplatform engine

Started by wh1sp3rik Sep 6, 2010 at 8:59 AM 2 replies 850+ views

Original Post

Sep 6, 2010 at 8:59 AM

Hello,
I would like to see your opinions.

Let's say, I am doing an engine and i would like to support DirectX and OpenGL.
Every renderer is using different class, which are "incompatible". for example GL_MATRIX and D3DXMATRIX. there ale lots of similar classes like these.

I tried to make a framework, which encapsulate all renderers into "one" class but after few tests, i can see .. it's much slower. because I have custom MATRIX class . so i need to save data to my MATRIX class from GL_MATRIX or D3DXMATRIX and opposite way too.

I don't know, how professionals are doing it ?
1/ they are using this slow method
2/ they are using one framework, but lots of code for selecting right matrix for GL and DX, but what if i want to sell the engine, user has to use different matrix class for differet renderer. (or vector, color, whatever)
3/ they are using two frameworks and when they want to port it to another platform, they just use some preprocessor directives to use different renderer.
4/ any other idea

I would like to start and work on the right way of multi engine and make it fast as possible.

i will be happy to read your opinions, ideas, advices :) Thank you very much.

phresnel

124

phresnel

Sep 6, 2010 at 9:17 AM

Personally I wouldn't expose the matrix coefficients and just provide methods like e.g. "rollRight(x)". That way you can also keep book of a cheap inverse, if you need it often (PBRT uses this approach). You can then compile-time-decide which one to use. Classes come in handy here.

Hodgman

Mod

5,991

Hodgman

Sep 6, 2010 at 9:42 AM

#3 - your different grahpics frameworks are selected at compile time. You have two sets of classes, which provide the same functions (same interface) but are implemented differently - there's no virtual functions required.

Also, your graphical matrices often come from another system altogether - e.g. if your graphical object is controlled by a physics engine, you might get the matrix in the form of a btTransform, which you've got to convert into a D3DXMATRIX anyway.

Zakwayda

1,120

Zakwayda

Sep 6, 2010 at 11:01 AM

Quote:
Every renderer is using different class, which are "incompatible". for example GL_MATRIX and D3DXMATRIX. there ale lots of similar classes like these.

Short answer to this question: use the same math library with both APIs. (There's no need to use a different math library for each, unless you're trying to take advantage of particular features or optimizations offered by one library or another or something like that.)

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