Basic render 3D perspective projection onto 2D screen with camera (without opengl)

Question

Let\'s say I have a data structure like the following:

Camera {
   double x, y, z

   /** ideally the camera angle is positioned to aim at the 0,0,0 point */         


        

Answer 1

Run it thru a ray tracer:

Ray Tracer in C# - Some of the objects he has will look familiar to you ;-)

And just for kicks a LINQ version.

I'm not sure what the greater purpose of your app is (you should tell us, it might spark better ideas), but while it is clear that projection and ray tracing are different problem sets, they have a ton of overlap.

If your app is just trying to draw the entire scene, this would be great.

Solving problem #1: Obscured points won't be projected.
Solution: Though I didn't see anything about opacity or transparency on the blog page, you could probably add these properties and code to process one ray that bounced off (as normal) and one that continued on (for the 'transparency').

Solving problem #2: Projecting a single pixel will require a costly full-image tracing of all pixels.
Obviously if you just want to draw the objects, use the ray tracer for what it's for! But if you want to look up thousands of pixels in the image, from random parts of random objects (why?), doing a full ray-trace for each request would be a huge performance dog.

Fortunately, with more tweaking of his code, you might be able to do one ray-tracing up front (with transparancy), and cache the results until the objects change.

If you're not familiar to ray tracing, read the blog entry - I think it explains how things really work backwards from each 2D pixel, to the objects, then the lights, which determines the pixel value.

You can add code so as intersections with objects are made, you are building lists indexed by intersected points of the objects, with the item being the current 2d pixel being traced.

Then when you want to project a point, go to that object's list, find the nearest point to the one you want to project, and look up the 2d pixel you care about. The math would be far more minimal than the equations in your articles. Unfortunately, using for example a dictionary of your object+point structure mapping to 2d pixels, I am not sure how to find the closest point on an object without running through the entire list of mapped points. Although that wouldn't be the slowest thing in the world and you could probably figure it out, I just don't have the time to think about it. Anyone?

good luck!

"Also, I don't understand in the wiki entry what is the viewer's position vers the camera position" ... I'm 99% sure this is the same thing.