51–60 of 74 posts
Technically this is not related to voxels ("volumetric pixels", so to say), which split the 3D space equally along all three axes. This is just a height map, a set of prisms, not entirely unlike a Doom map. Every prism has a regular fixed-size square base. For 1992, this was mind-boggling though.
Playing it on a decent PC in 2992 was mind blowing.
Earlier quoted context omitted.
It's kind of weird to call them "columns of voxels" when the columns can't have gaps and the "voxels" below the topmost are ignored completely. Which is to say, they're just columns...which is (definitionally) just a height map. In fact, an octree for this approach would be _meaningfully worse_ because finding "the topmost voxel" in each column is O(logn)—or maybe worse?—versus O(1) for a height map. With no benefits…
> It's kind of weird to call them "columns of voxels" when the columns can't have gaps No, it's not weird. The columns don't have gaps because they are columns represented by a height map, which can't display arbitrary voxel geometry (unlike octrees), but that doesn't mean they can't display voxel geometry at all. > Which is to say, they're just columns...which is (definitionally) just a height map. Yes. A height map…
A height map can represent voxel data if the columns are integer heights, in the same way an integer can "represent" an infinite number of countable things. It's like saying the number 7 is "related" to a group of 7 ducks. The relationship is kind of meaningless.
But more importantly height maps can use also floating point heights in which case there's no reasonable mapping between the two. So your statement isn't generally true.
I used this approach in one of my demos: https://www.youtube.com/watch?v=xjbDxvboOjo . Plot twist: the highmap is dynamically-generated.
This sure brings back memories. I remember figuring all this out as a self-taught teenager (pre-internet) with some books, a whole lot of time, and only a high-school level understanding of trigonometry. I built different versions - first in Pascal, then C, then Assembly. Figuring out the algorithm was hard, but one of the optimizations I was most proud of was inventing (or so I thought) lookup tables to get around t…
If you render columns instead of rows you can render near-to-far without a Y-buffer and with zero overdraw. :)
If you render columns instead of rows you can render near-to-far without a Y-buffer and with zero overdraw. :)
This is true. I vaguely remember there was something about the VGA architecture of the day that made this approach much slower, but I might be misremembering. My recollection of it is fuzzy. I'm hoping someone will chime in to remind me what I might be thinking of. It might also just have been that this approach didn't work well with my lookup table optimization (see my other post).
Earlier quoted context omitted.
This is true. I vaguely remember there was something about the VGA architecture of the day that made this approach much slower, but I might be misremembering. My recollection of it is fuzzy. I'm hoping someone will chime in to remind me what I might be thinking of. It might also just have been that this approach didn't work well with my lookup table optimization (see my other post).
You might be thinking of unchained VGA modes but in unchained modes you want to draw columns because that means you only have to switch which memory plane is active four times instead of every four pixels, ie select plane 0, draw column 0, 4, 8, etc then select plane 1 and draw columns 1, 5, 9, etc etc
Earlier quoted context omitted.
This is true. I vaguely remember there was something about the VGA architecture of the day that made this approach much slower, but I might be misremembering. My recollection of it is fuzzy. I'm hoping someone will chime in to remind me what I might be thinking of. It might also just have been that this approach didn't work well with my lookup table optimization (see my other post).
I imagine that far map squares are more than one pixel wide so that read is amortized. Not so if going vertically.
Had to keep the memory use down and multiplication was really computationally expensive.
Technically this is not related to voxels ("volumetric pixels", so to say), which split the 3D space equally along all three axes. This is just a height map, a set of prisms, not entirely unlike a Doom map. Every prism has a regular fixed-size square base. For 1992, this was mind-boggling though.