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Hey all, just wondering if anyone knows the framework of a doom-style 3d engine, in pseudocode?

I'm hoping to be able to do this using sine and cosine with an input range of 0 to 255, and an output range of -255 to 255.
I'm mainly stuck on how to perform the rotation matrix with that restriction.
What kind of a question is that
Are you referring to a raycasting engine? I know Wolfenstein 3D used it, but Doom may have built off of it. I found a good tutorial here http://www.playfuljs.com/a-first-person-engine-in-265-lines/. patrickdavidson also made one for the CE here: https://www.cemetech.net/programs/index.php?mode=file&id=1588.

Hope this helps!
OldNewTimer wrote:
Are you referring to a raycasting engine? I know Wolfenstein 3D used it, but Doom may have built off of it. I found a good tutorial here http://www.playfuljs.com/a-first-person-engine-in-265-lines/. patrickdavidson also made one for the CE here: https://www.cemetech.net/programs/index.php?mode=file&id=1588.

Hope this helps!


Something like that, exept instead of using a grid, I would be using a list of coordinates, then using two indexes of that list to make walls.
MateoConLechuga wrote:
What kind of a question is that

What I need help with is how to make that -255 to 255 range useful, and I can't use decimals, unless I store them seperately.
OldNewTimer wrote:
Are you referring to a raycasting engine? I know Wolfenstein 3D used it, but Doom may have built off of it. I found a good tutorial here http://www.playfuljs.com/a-first-person-engine-in-265-lines/. patrickdavidson also made one for the CE here: https://www.cemetech.net/programs/index.php?mode=file&id=1588.

Hope this helps!


The original Doom 3D was not a raycaster (though Wolfenstein was) . It used something a bit more complicated called binary space partitioning. I can't do it justice; check out the article.

For your purposes, raycasting is a good option. I recommend doing it in C, because C lets you do decimals and is much better than ICE at this stuff. (More graphics than math? Use ICE. More math than graphics? Use C. Want to give yourself headaches for the rest of your life while failing to accomplish your goal for an entire year or more? Use Assembly.)
vertexs go spiny spiny around the camera as the camera rotates thanks to the spiny spiny formula:
x′=xcosθ−ysinθ
y′=ycosθ+xsinθ

then get projected from from 3d space into screen space. The formula for that, if you dont want to use matrices, would be something like this iirc:
x' = x/z*screen_width+(screen_width/2)
y' = y/z*screen_height+(screen_height/2)

once you know the on screen pixel potion of two points you can draw lines between them or whatever to make a wireframe model
c4ooo wrote:
vertexs go spiny spiny around the camera as the camera rotates thanks to the spiny spiny formula:
x′=xcosθ−ysinθ
y′=ycosθ+xsinθ

then get projected from from 3d space into screen space. The formula for that, if you dont want to use matrices, would be something like this iirc:
x' = x/z*screen_width+(screen_width/2)
y' = y/z*screen_height+(screen_height/2)

once you know the on screen pixel potion of two points you can draw lines between them or whatever to make a wireframe model


Yes, I've done that before; what I need is how to make a number between -255 to 255 useful when sine and cosine are normally decimals, and I can't use decimals.
beckadamtheinventor wrote:
c4ooo wrote:

Yes, I've done that before; what I need is how to make a number between -255 to 255 useful when sine and cosine are normally decimals, and I can't use decimals.

Its just a different range, use the normal formulas:
x′=xcosθ−ysinθ
y′=ycosθ+xsinθ
but divide by 256 at the end:
x′=(xcosθ−ysinθ)/256
y′=(ycosθ+xsinθ)/256
(Dividing by 256 is faster then by 255, and the visual difference is negligible)

see also: https://www.omnimaga.org/axe-language/how-to-calculate-(using-trig)-rotation-in-axe/msg399875/#msg399875
I agree on using a power of 8 to represent +/-1.

I've used the +/- 64 range for scaling trig in the past to keep things in 1-byte and also for math routine optimisation - but it's more of a horses for courses kind of thing.
c4ooo wrote:
beckadamtheinventor wrote:
c4ooo wrote:

Yes, I've done that before; what I need is how to make a number between -255 to 255 useful when sine and cosine are normally decimals, and I can't use decimals.

Its just a different range, use the normal formulas:
x′=xcosθ−ysinθ
y′=ycosθ+xsinθ
but divide by 256 at the end:
x′=(xcosθ−ysinθ)/256
y′=(ycosθ+xsinθ)/256
(Dividing by 256 is faster then by 255, and the visual difference is negligible)

see also: https://www.omnimaga.org/axe-language/how-to-calculate-(using-trig)-rotation-in-axe/msg399875/#msg399875


tr1p1ea wrote:
I agree on using a power of 8 to represent +/-1.

I've used the +/- 64 range for scaling trig in the past to keep things in 1-byte and also for math routine optimisation - but it's more of a horses for courses kind of thing.


Thank you!
  
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