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opengllover
02-22-2003, 09:18 AM
I want to make "finite element analysis" using opengl in my own software but i donnot know how to do.i cannot find any books or information about it.Wise man,can u give me your knowledge ?i am a fresh ...

gib
02-22-2003, 07:09 PM
I know more about Finite Element Analysis (FEA) than I know about OpenGL (which may not be saying much). They are very different animals, although both involve a lot of 3D geometry. FEA is a technique for solving systems of partial differential equations, mathematical formulations for physical quantities like temperature, stress, fluid pressure and velocity, electric field intensity, etc. etc.

The starting point for an FE solution is creating a representation of the region, structure or object by finite elements, which are in the 2D case generally triangles or quadrilaterals, or in the 3D case generally tetrahedrons or quad bricks. This representation (called a mesh) can be thought of as chopping the region up into a large number of small pieces. The corners (and maybe other points, e.g. edge midsides) of the elements are called nodes, and the mathematical technique (which is fairly complex) solves for the values of the quantities of interest at these nodes. Serious calculus and algebra are used in this procedure.

The point of similarity between FEA and OpenGL is that for certain classes of problems the FEA mesh looks just like an OpenGL representation of an object or scene. Typically triangular faces are used in OpenGL to represent a curved surface, e.g. the surface of a car. The faces and verticies of the OpenGL description of the car are like FEA elements and nodes, in the case that the FE analysis uses only the external shape of the car (e.g. to analyse air flow over the body, maybe to determine drag). On the other hand a stress analysis of the body would have to include 3D elements (to represent the thicker structural members) which have no analogue in OpenGL.

If you really want to know about FEA, the first thing to realise is that your FEA model would be completely separate from OpenGL. You might use OpenGL to display the mesh, and to display results from the model, but that would be it.

Googling will quickly reveal the popular introductory texts. But be warned, the mathematics is not for the faint-hearted.

Gib