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Old 19 June 2017, 06:30   #1
sandruzzo
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Ray casting

is there a good ray casting tutorial for amiga?
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Old 19 June 2017, 12:41   #2
roondar
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I don't know of one, but isn't it effectively the same thing as on the PC, but adding C2P conversion?
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Old 19 June 2017, 13:06   #3
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isn't it effectively the same thing as on the PC
That's exactly what is is, there is no "Amiga raycasting" at all.
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Old 19 June 2017, 16:57   #4
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Well, on Amiga you usually do it into a chunky buffer in fastmem and then use C2P into chip mem, but that's the only real difference.

Bisquit on YouTube has some good tutorials on raycasting.
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Old 19 June 2017, 17:36   #5
Thorham
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What does ray casting have to do with chunky graphics?
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Old 19 June 2017, 17:45   #6
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What does ray casting have to do with chunky graphics?
Nothing per se - except that (assuming your rays are intersecting with vertical walls) you're processing the scene one column at a time, which is horribly inefficient if you're rendering to a planar framebuffer.
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Old 20 June 2017, 16:35   #7
sandruzzo
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Since Amiga is a word(16 bit) machine, was thinking about doing ray casting with this in mind, and maybe get rid of c2p
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Old 20 June 2017, 17:44   #8
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Nothing per se - except that (assuming your rays are intersecting with vertical walls) you're processing the scene one column at a time, which is horribly inefficient if you're rendering to a planar framebuffer.
Yes, but why not just use integer based vectors? Seems faster than bitmap based ray casting, unless I'm wrong (never done it).
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Old 20 June 2017, 18:05   #9
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Since Amiga is a word(16 bit) machine, was thinking about doing ray casting with this in mind, and maybe get rid of c2p
Sure, that's doable if you're rendering walls with flat shading - but as soon as you introduce texture mapping into the mix you have loads of shifting and masking to deal with before you can write a 16-bit word.
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Old 20 June 2017, 18:15   #10
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Sure, that's doable if you're rendering walls with flat shading - but as soon as you introduce texture mapping into the mix you have loads of shifting and masking to deal with before you can write a 16-bit word.
What's the actual use case for ray casting here? I'm thinking of ray casting as used in current 3D games...
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Old 20 June 2017, 18:15   #11
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Yes, but why not just use integer based vectors? Seems faster than bitmap based ray casting, unless I'm wrong (never done it).
I've written a raycaster but not done 3D graphics with vectors. The big draw of raycasting is simplicity - a simple step-by-step procedure for each column on the screen tells you which walls have to be drawn (just the first one you hit unless you're dealing with transparent textures), which texture column should be drawn, and at which scale. No need to depth-sort polygons, deal with backface culling, view cones, clipping and all the stuff that comes with polygon-based 3D graphics, even before you've added texture mapping into the mix.

(Just to be clear, I'm talking about raycasting as in Wolfenstein 3D here - Sandruzzo, is that what you meant?)
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Old 20 June 2017, 18:21   #12
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Just to be clear, I'm talking about raycasting as in Wolfenstein 3D here
Right, now it makes sense. Didn't realize the term was used in that context.
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Old 20 June 2017, 18:35   #13
sandruzzo
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based 3D graphics, even before you've added texture mapping into the mix.

(Just to be clear, I'm talking about raycasting as in Wolfenstein 3D here - Sandruzzo, is that what you meant?)
Yes. I meant that

Maybe we some good lookup table we should be able to do texture mapping word based.
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Old 20 June 2017, 21:32   #14
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Sure, that's doable if you're rendering walls with flat shading - but as soon as you introduce texture mapping into the mix you have loads of shifting and masking to deal with before you can write a 16-bit word.
What if we use just one bitplane texture?
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Old 21 June 2017, 01:06   #15
robinsonb5
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What if we use just one bitplane texture?
We still have the problem of assembling a 16-bit word from 16 independently selected texture pixels - so still lots of masking and shifting.
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