7 ms·

now this may be a dimb question, but why would you start there? as far as i understand, 2d and 3d have literally zero to do with each other in how they are ren

now this may be a dimb question, but why would you start there? as far as i understand, 2d and 3d have literally zero to do with each other in how they are rendered. one is a bunch of triangles. the other is lines, curves, thickness, gradients, and fonts (which are essentially little programs)

blondin 6y ago
that's not a dumb question! it's my own fault. i only have knowledge of 2D graphics.
chrisseaton 6y ago
> the other is lines, curves, thickness, gradients, and fonts You can reduce all these to drawing triangles.
- deleted 6y ago
  [deleted]
- Jasper_ 6y ago
  Doing that reduction is surprisingly difficult, and usually a serial algorithm that runs on the CPU, and a naive approach is a resulting triangle set is not efficient to a GPU, but that's what toolkits like cairo, Direct2D, nanovg do. Raph is describing an architecture where path evaluation happens on the GPU, without being baked to triangles.
- raphlinus 6y ago
  > You can reduce all these to drawing triangles. You can, people have tried this, and it sucks. The main problem is that the conversion of Bézier paths to triangles is a hard problem with lots of conditional branching. Even when you do it, there is the other problem of rendering triangles with really good antialiasing, MSAA forces a compromise between performance and quality. By contrast, piet-gpu does an exact-area calculation for antialiasing. So it's not a question of whether you can do it, but whether it works well, and approaches like piet-gpu absolutely stomp triangles.
  - Const-me 6y ago
    > there is the other problem of rendering triangles with really good antialiasing Easier than you think. Here's couple lines of pixel shader that does that, with really good antialiasing and without MSAA: https://github.com/Const-me/Vrmac/blob/master/Vrmac/Draw/Shaders/drawPS.hlsl#L116-L143 https://github.com/Const-me/Vrmac/blob/master/Vrmac/Draw/Sha...
- dungdang 6y ago
  yes, you can draw 2d in 3d space. this thread however is about 3d being built on top of 2d. not 2d being built on top of 3d.

blondin 6y ago

that's not a dumb question! it's my own fault. i only have knowledge of 2D graphics.

chrisseaton 6y ago

> the other is lines, curves, thickness, gradients, and fonts You can reduce all these to drawing triangles.

deleted 6y ago
[deleted]
Jasper_ 6y ago
Doing that reduction is surprisingly difficult, and usually a serial algorithm that runs on the CPU, and a naive approach is a resulting triangle set is not efficient to a GPU, but that's what toolkits like cairo, Direct2D, nanovg do. Raph is describing an architecture where path evaluation happens on the GPU, without being baked to triangles.
raphlinus 6y ago
> You can reduce all these to drawing triangles. You can, people have tried this, and it sucks. The main problem is that the conversion of Bézier paths to triangles is a hard problem with lots of conditional branching. Even when you do it, there is the other problem of rendering triangles with really good antialiasing, MSAA forces a compromise between performance and quality. By contrast, piet-gpu does an exact-area calculation for antialiasing. So it's not a question of whether you can do it, but whether it works well, and approaches like piet-gpu absolutely stomp triangles.
- Const-me 6y ago
  > there is the other problem of rendering triangles with really good antialiasing Easier than you think. Here's couple lines of pixel shader that does that, with really good antialiasing and without MSAA: https://github.com/Const-me/Vrmac/blob/master/Vrmac/Draw/Shaders/drawPS.hlsl#L116-L143 https://github.com/Const-me/Vrmac/blob/master/Vrmac/Draw/Sha...
dungdang 6y ago
yes, you can draw 2d in 3d space. this thread however is about 3d being built on top of 2d. not 2d being built on top of 3d.