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ssloy / tinyrenderer

A brief computer graphics / rendering course
https://github.com/ssloy/tinyrenderer/wiki
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Lesson 4 what is rz in matrix in "Time to work in full 3D" #90

Open lukesawicki opened 2 years ago

lukesawicki commented 2 years ago

I cannot understand in paragraph "Time to work in full 3D" what is rz in matrix. Is it somehow connected with "retro-projection" which i do not understand to. I started from lesson 4 because I started programmin software renderer almost year ago and now I can draw lines and triangles with colour, but this lesson is not exactly helpfull because this too things "rz" in matrix and "retro-projection".

Buzzefall commented 2 years ago

Hi, lukesawicki! Try this tutorial, it really explains a lot: https://www.ocf.berkeley.edu/~horie/persp.txt. There, 4D-Space or matrices are not mentioned whatsoever so it is simpler to understand, but matrices are just clever way to write down same ideas.

The short answer is that r = 1/D, where D is the distance between the camera position (your eye, for example) and the screen on which we project world objects.