8 ms·

Rendering my (billiard) balls in a fragment shader

244 points by sysrpl 4y ago

londons_explore 4y ago
What's the benefit of rendering using this technique over a regular sphere rendered with the usual pipeline?
- cowtools 4y ago
  It is faster for the case of a "top-down" 2D game. You render this and just draw a single quad per ball. You do not really have any vert shader.
- sysrpl 4y ago
  Well first of you get infinite smoothness and better lighting (and reflections if you add them) because there is no underlying geometry. It's just math. It's also much faster, as you're only giving the GPU four vertices defining the square. This can even be sped up further by using point sprites which consume only one vertex.
  - cowtools 4y ago
    I've been advised not to use point sprites. Apparently, most GPU inplementations merely convert it into a quad in the backend, and gl_PointSize seems to have a soft maximum that depends on implementation. I've found a mechanism that uses the "interleaved attribs" feature of transform feedbacks to spit out 4 verts at a time (as six to draw two GL_TRIANGLES) into a buffer that a quad-drawing shader program consumes. Using GL_POINTS/gl_PointCoord is probably better though just for teaching children fundamentals, I just wish that it actually worked properly in practice.
  - gsliepen 4y ago
    "It's just math." But math can be expensive, and in the fragment shader you are calculating everything per-pixel, whereas if you provide your geometry to the vertex shader, you only have to calculate something once per vertex, which is usually much less. Furthermore, depending on the GPU and the exact workload, it can be that vertex and fragment shading can run in parallel. In that case, it is better to spread the load over both, instead of letting the fragment shaders do everything. The same goes for texturing. Instead of calculating most of the ball's color pattern in the fragment shader, and only using texture lookups for the number itself, if you just have a texture covering the whole ball, you basically offload a lot of computation to the texture units. That said, for a pool game where the balls are one of the most important items on the screen, it's probably worth it to get the perfect smoothness and lighting, as you mentioned.
sysrpl 4y ago
Here is a summary I wrote on my attempt to render balls using only a fragment shader. I am pretty happy with the result, and I've included a breakdown of the creation process.
- prox 4y ago
  Cool, I recently started with GLSL, and it’s interesting there are many roads that lead to a similar solution (how I draw circles or make a center is tad different) Where or how did you learn GLSL?
  - sysrpl 4y ago
    I was around and writing OpenGL when we started getting the first programmable cards. Nvidia shot out first with their Cg language, but I held back and waited for the "Orange Book" to come up. I bought it right away and learned from it and by looking at other peoples shaders. https://duckduckgo.com/?q=opengl+orange+book https://duckduckgo.com/?q=opengl+orange+book Also the quick reference card helps https://duckduckgo.com/?q=glsl+quick+reference&t=h_&ia=web https://duckduckgo.com/?q=glsl+quick+reference&t=h_&ia=web
    - prox 4y ago
      So you are a veteran, compared to me, just started this year, really reminded why I should have been more observant in math class :) The resources are really good, hadn’t found something like that yet!
    - pjmlp 4y ago
      Small correction, NVidia Cg was only the first on PC. We had Renderman on NeXT, TI TMS34010, and a couple of other attempts outside the PC world.
- radarsat1 4y ago
  Great write up, that was a fun read. In understanding how the rotation was implemented, it took me longer than it probably should have to realize that the normal map (which I think of in terms of lighting) is actually a radial position on the sphere. I had to go back and forth with the final and original code a few times, and finally noted that "n" gets renamed to "point" when it becomes an argument to colorLookup. This dual usage of the normal for lighting brightness calculation and as a radial position on the sphere surface for looking up the color makes sense in retrospect but is also a somewhat subtle aspect that you might want to address more explicitly in your text instead of just silently renaming the variable in the code.
pixel_tracing 4y ago
Came for the title, stayed for the shaders. Well written and very educational
- eyelidlessness 4y ago
  > Came for the title Well played Edit: I’ll take the downvotes, the author edited the thing for silly innuendo, it’s silly, I’ll have fun too and take my lashes.
can16358p 4y ago
Could we change the title to the actual title of the article? I was, let's say, really scared when tapping the link with the current title.
- sysrpl 4y ago
  I fixed it. Thanks.
  - javawizard 4y ago
    What was it originally? Hard to get more amusing than the actual article title...
    - b4je7d7wb 4y ago
      The actual article was titled "Rendering Pool Balls". He fixed it by updating the article title rather than the HN submission(which I don't think you even can).
      - thunderbong 4y ago
        You can. Within a certain amount of time of having submitted.
    - thunderbong 4y ago
      "Rendering Pool Balls" https://news.ycombinator.com/item?id=32797146 https://news.ycombinator.com/item?id=32797146
  - NavinF 4y ago
    Well played
causality0 4y ago
From the HN guidelines: please use the original title, unless it is misleading or linkbait; don't editorialize. The correct title is Rendering Pool Balls, not "Rendering my balls in a fragment shader".
- sysrpl 4y ago
  Fixed.
  - TaylorAlexander 4y ago
    I love how you fixed it lmao.
  - ketzo 4y ago
    …well played
  - jahewson 4y ago
    Outrageous! Well done.
  - quickthrower2 4y ago
    Based!
  - echelon 4y ago
    Malicious compliance. Love it. I'll be referencing this in the future.
  - password4321 4y ago
    A new HN meme is born.
  - dang 4y ago
    Not to pee on your party, but I wouldn't want to the users who click on that title expecting...something else, to be disappointed. Therefore I have made the minimum viable edit. (For anyone wondering: the submitted title was "Rendering my balls in a fragment shader" and the article title was changed from "Rendering pool balls" to that.)
pfoof 4y ago
Cool to read about C-like GLSL on a Pascal website
- deleted 4y ago
  [deleted]
- pjmlp 4y ago
  In theory if Free Pascal had a SPIR-V backend, it could be used as well.
xanthine 4y ago
I happened to notice that PI is #define'd to 3.1415926538, which isn't the correctly rounded off value of 3.14159265358... Seems like they missed a '5'.
- sysrpl 4y ago
  Lol, wow what a find. You notice the details. I corrected it. Thank you.
  - xanthine 4y ago
    At school, I somehow talked myself into a dumb competition with my math geek about memorizing digits of pi. I won, with 35 digits memorized (he gave up early; that's also around where the first '0' occurs in pi). I don't miss any opportunities to test that I still remember them correctly, to this day. ;)
    - ncmncm 4y ago
      I had a hard time getting past the "399" out about 43. I wanted to round it to "4". But these days I would rather memorize tau: 6.28318530717958647692528676655900576839433879875021 It has that "00" at 27 digits in that must be got past.
- NKosmatos 4y ago
  That’s a little bit more accuracy than what is needed for this post, but good catch :-) https://www.jpl.nasa.gov/edu/news/2016/3/16/how-many-decimals-of-pi-do-we-really-need/ https://www.jpl.nasa.gov/edu/news/2016/3/16/how-many-decimal...
  - johnrackles 4y ago
    Thats an interestring post, thank you! Do you think that's why for example JavaScripts Math.PI also comes out to 3.141592653589793?
    - 4y ago
samlittlewood 4y ago
It might be interesting to explore with the students why this would not be quite right for a general 3D view, and how it could be fixed. Conic sections, etc.
spuz 4y ago
I'm just getting my feet wet with shaders myself. Could this fragment shader be used in a "real" 3D game? At the moment, the sphere is orthographicly projected onto the screen so the sphere will always appear as a circle rather than an ellipse. How easy would it be to use this shader in place of a spherical mesh as you might find in a typical geometry based 3D render? I.e. could you use the same technique and render multiple balls on the screen with positions in 3D space and rendered correctly taking into account any distortion caused by the camera?
- Sharlin 4y ago
  It could be used as a sprite that looks like real geometry with some tweaking.
- Zinu 4y ago
  I'm also new to shaders, so I might be wrong: Camera distortion (/perspective) is done in the vertex shader, this post here presents a fragment shader. So if you take a quad, in the vertex shader then rotate it so it'll face the camera (i.e. all vertices have same z/depth value in clip space), you can then probably use this fragment shader to render the ball. You have to rotate the quad to face the camera, since it has to cover the area where the ball may render (imagine the extreme case: if the quad is perpendicular to the camera, it looks like a line to the camera, you could only render the ball within that line, it wouldn't protrude to the left or right).
  - Doxin 4y ago
    > You have to rotate the quad to face the camera Or you only run the center point through the camera transform, and then render the quad in screen space. Should be cheaper in terms of compute.
- sysrpl 4y ago
  It can be incorporated into a 3D scene as long as you can make a square billboard . You may have problems with clipping that' you need to address manually, but it might be worth it as you can get better visuals, assuming you are trying to render spheres. As far as I know there shouldn't be any distortion issues. A sphere will always look like a circle from any perspective. Well that is unless it's really really big or your are really really tiny and you give the size difference you are relatively close to its surface. At that perspective it just look like a flat plane.
halaiis 4y ago
This reminds me of the same rendering technique described in Hustle Kings for the PS3. There was a write up done, however shader code was not included. https://web.archive.org/web/20130913033312/http://www.voofoostudios.com/?p=33 https://web.archive.org/web/20130913033312/http://www.voofoo...
- sysrpl 4y ago
  That's very interesting. Thank you for the link. From what I read and see in the images, I gather he's done the same thing I have, as you guessed as well. Obviously he's going much further. The author is using a subtle bump map (simulating balls scratches and imperfections), a reflection map with a gradient and indecent angle, what looks to be a faux sub surface scattering effect. Also he is placing his balls in a 3D environment with nice shadows that really help to sell the illusion. That's a good find and an interesting read. Thank you.
the__alchemist 4y ago
Good timing - I was procrastinating on HN instead of trying to fix my phucked-up phong; you've helped me do both.
- sysrpl 4y ago
  With a good phong it's all about the dot products and specular highlight (if you using highlights). Make sure you clamp the dot products and give yourself a minimum ambient light value of around 0.15 to 0.2.
- Jasper_ 4y ago
  The thing that got me, in a classic Phong, you have to test whether dot > 0.0, it really won't work outside of the front hemiphere. The clamp isn't enough.
benj111 4y ago
Fyi. "Rendering my balls" says something very different to "rendering balls". Although the hair would be impressive if you managed to do it. (Testicles btw)
- silverfox17 4y ago
  I believe they titled it that way on purpose.
- hermitcrab 4y ago
  (Testes btw)
  - benj111 4y ago
    I like how you can confidently correct me over the hyper precise term 'balls'. Even though the term 'balls' generally includes the sack (and hair) which neither of us accounted for.
noam_compsci 4y ago
Risky click of the day
gitgud 4y ago
Very nice! not sure if you've heard of [1] ShaderToy, but it's pretty good for sharing/viewing shaders online. [1] https://www.shadertoy.com/ https://www.shadertoy.com/
- gfody 4y ago
  https://www.shadertoy.com/view/XlfBRH https://www.shadertoy.com/view/XlfBRH https://www.shadertoy.com/view/MtlGD8 https://www.shadertoy.com/view/MtlGD8
rawoke083600 4y ago
The sexes(including all modern derivatives) may really be equal, but I for one truley enjoyed this title submitted most likely by a male :p
acqbu 4y ago
To me, those balls are perfect
MaxBorsch228 4y ago
I guessed correctly by the title that the article is about coding a 3d image, but was waiting for the classic "two balls and a cylinder" scene, which college students naturally come up with in path tracing assignment in computer graphics courses.
virtualritz 4y ago
In the 90's, texture maps were a luxury for anything. As a result shaders (for offline rendering, realtime shading languages didn't exist yet) were doing everything procedurally. Here is the only image I could find of the RenderMan Shading Language VIDI SPORTS SHADERS Makina Works sold at the time (you got no source, just bytecode understood by Pixar's implementation at the time, AFAIK): https://web.cs.wpi.edu/~matt/courses/cs563/talks/renderman/SportsBalls.jpg https://web.cs.wpi.edu/~matt/courses/cs563/talks/renderman/S... What is interesting here is that the shaders did everything on a sphere primitive. All RenderMan implementations at the time (there were more than just Pixar's) were micropolygon renderers. I.e. displacement was almost free in terms of compute overhead. Even the football operated on a sphere that the shader deformed into the resp. shape. All patterns, stripes etc. were procedurally generated. Each shader had texture slots to apply custom logos.
ricardobayes 4y ago
Even after 10 years I still have anxiety looking at OpenGL code. I still don't understand why we needed to write ray-tracing during a BSc course starting from a blinking cursor. The professor tried to defend that at the time, but I firmly believe that it is the wrong curriculum for a 20 year old CS student. Computer graphics were and are niche programming, and should not be taught main-stream. Out of 100 graduates maybe one will ever use this, why not use some common sense and teach something useful?
- skywal_l 4y ago
  Because graphics is fun. It's a good way to engage with students. Beside, what's important is not the outcome but the journey. You learn to read documentation, to design, to debug and more importantly you learn to learn. Which is what higher education is about.
- NavinF 4y ago
  inb4 you get 10 replies along the lines of "wow I wish my professors let me do something cool like ray-tracing. I spent 4 years implementing cache-inefficient data structures that nobody uses in an ancient version of some programming language that nobody uses in a crappy env doesn't even have a real debugger" Not that I can relate. I dropped out of uni well before I encountered anything that would discourage me from going into software :)
- npteljes 4y ago
  Education is about exercising the mind. I don't think many play with inflated balls in their adulthood, yet it's very important to teach children hand-eye coordination, team play, and other concepts so that they become better functioning humans. There are problems with the curriculum though, one of them that it plays catch-up with the state of the world. IT in particular moves very fast. Graphics programming is not one of these things however. For example, if you've done the courses, and experiences just how hard it is to crate anything in 3d, you can better appreciate the work that goes into modern 3d engines. Look at this beautiful breakdown of the inner workings of the GTA V engine: http://www.adriancourreges.com/blog/2015/11/02/gta-v-graphics-study/ http://www.adriancourreges.com/blog/2015/11/02/gta-v-graphic...
deleted 4y ago
[deleted]
drzel 4y ago
not sure about that red 10-ball tho.
pupppet 4y ago
Pretty interesting how he's wrapping the text before the curved image on the right.

244 points by sysrpl 4y ago

londons_explore 4y ago

What's the benefit of rendering using this technique over a regular sphere rendered with the usual pipeline?

cowtools 4y ago
It is faster for the case of a "top-down" 2D game. You render this and just draw a single quad per ball. You do not really have any vert shader.
sysrpl 4y ago
Well first of you get infinite smoothness and better lighting (and reflections if you add them) because there is no underlying geometry. It's just math. It's also much faster, as you're only giving the GPU four vertices defining the square. This can even be sped up further by using point sprites which consume only one vertex.
- cowtools 4y ago
  I've been advised not to use point sprites. Apparently, most GPU inplementations merely convert it into a quad in the backend, and gl_PointSize seems to have a soft maximum that depends on implementation. I've found a mechanism that uses the "interleaved attribs" feature of transform feedbacks to spit out 4 verts at a time (as six to draw two GL_TRIANGLES) into a buffer that a quad-drawing shader program consumes. Using GL_POINTS/gl_PointCoord is probably better though just for teaching children fundamentals, I just wish that it actually worked properly in practice.
- gsliepen 4y ago
  "It's just math." But math can be expensive, and in the fragment shader you are calculating everything per-pixel, whereas if you provide your geometry to the vertex shader, you only have to calculate something once per vertex, which is usually much less. Furthermore, depending on the GPU and the exact workload, it can be that vertex and fragment shading can run in parallel. In that case, it is better to spread the load over both, instead of letting the fragment shaders do everything. The same goes for texturing. Instead of calculating most of the ball's color pattern in the fragment shader, and only using texture lookups for the number itself, if you just have a texture covering the whole ball, you basically offload a lot of computation to the texture units. That said, for a pool game where the balls are one of the most important items on the screen, it's probably worth it to get the perfect smoothness and lighting, as you mentioned.

sysrpl 4y ago

Here is a summary I wrote on my attempt to render balls using only a fragment shader. I am pretty happy with the result, and I've included a breakdown of the creation process.

prox 4y ago
Cool, I recently started with GLSL, and it’s interesting there are many roads that lead to a similar solution (how I draw circles or make a center is tad different) Where or how did you learn GLSL?
- sysrpl 4y ago
  I was around and writing OpenGL when we started getting the first programmable cards. Nvidia shot out first with their Cg language, but I held back and waited for the "Orange Book" to come up. I bought it right away and learned from it and by looking at other peoples shaders. https://duckduckgo.com/?q=opengl+orange+book https://duckduckgo.com/?q=opengl+orange+book Also the quick reference card helps https://duckduckgo.com/?q=glsl+quick+reference&t=h_&ia=web https://duckduckgo.com/?q=glsl+quick+reference&t=h_&ia=web
  - prox 4y ago
    So you are a veteran, compared to me, just started this year, really reminded why I should have been more observant in math class :) The resources are really good, hadn’t found something like that yet!
  - pjmlp 4y ago
    Small correction, NVidia Cg was only the first on PC. We had Renderman on NeXT, TI TMS34010, and a couple of other attempts outside the PC world.
radarsat1 4y ago
Great write up, that was a fun read. In understanding how the rotation was implemented, it took me longer than it probably should have to realize that the normal map (which I think of in terms of lighting) is actually a radial position on the sphere. I had to go back and forth with the final and original code a few times, and finally noted that "n" gets renamed to "point" when it becomes an argument to colorLookup. This dual usage of the normal for lighting brightness calculation and as a radial position on the sphere surface for looking up the color makes sense in retrospect but is also a somewhat subtle aspect that you might want to address more explicitly in your text instead of just silently renaming the variable in the code.

pixel_tracing 4y ago

Came for the title, stayed for the shaders. Well written and very educational

eyelidlessness 4y ago
> Came for the title Well played Edit: I’ll take the downvotes, the author edited the thing for silly innuendo, it’s silly, I’ll have fun too and take my lashes.

can16358p 4y ago

Could we change the title to the actual title of the article? I was, let's say, really scared when tapping the link with the current title.

sysrpl 4y ago
I fixed it. Thanks.
- javawizard 4y ago
  What was it originally? Hard to get more amusing than the actual article title...
  - b4je7d7wb 4y ago
    The actual article was titled "Rendering Pool Balls". He fixed it by updating the article title rather than the HN submission(which I don't think you even can).
    - thunderbong 4y ago
      You can. Within a certain amount of time of having submitted.
  - thunderbong 4y ago
    "Rendering Pool Balls" https://news.ycombinator.com/item?id=32797146 https://news.ycombinator.com/item?id=32797146
- NavinF 4y ago
  Well played

causality0 4y ago

From the HN guidelines: please use the original title, unless it is misleading or linkbait; don't editorialize. The correct title is Rendering Pool Balls, not "Rendering my balls in a fragment shader".

sysrpl 4y ago
Fixed.
- TaylorAlexander 4y ago
  I love how you fixed it lmao.
- ketzo 4y ago
  …well played
- jahewson 4y ago
  Outrageous! Well done.
- quickthrower2 4y ago
  Based!
- echelon 4y ago
  Malicious compliance. Love it. I'll be referencing this in the future.
- password4321 4y ago
  A new HN meme is born.
- dang 4y ago
  Not to pee on your party, but I wouldn't want to the users who click on that title expecting...something else, to be disappointed. Therefore I have made the minimum viable edit. (For anyone wondering: the submitted title was "Rendering my balls in a fragment shader" and the article title was changed from "Rendering pool balls" to that.)

pfoof 4y ago

Cool to read about C-like GLSL on a Pascal website

deleted 4y ago
[deleted]
pjmlp 4y ago
In theory if Free Pascal had a SPIR-V backend, it could be used as well.

xanthine 4y ago

I happened to notice that PI is #define'd to 3.1415926538, which isn't the correctly rounded off value of 3.14159265358... Seems like they missed a '5'.

sysrpl 4y ago
Lol, wow what a find. You notice the details. I corrected it. Thank you.
- xanthine 4y ago
  At school, I somehow talked myself into a dumb competition with my math geek about memorizing digits of pi. I won, with 35 digits memorized (he gave up early; that's also around where the first '0' occurs in pi). I don't miss any opportunities to test that I still remember them correctly, to this day. ;)
  - ncmncm 4y ago
    I had a hard time getting past the "399" out about 43. I wanted to round it to "4". But these days I would rather memorize tau: 6.28318530717958647692528676655900576839433879875021 It has that "00" at 27 digits in that must be got past.
NKosmatos 4y ago
That’s a little bit more accuracy than what is needed for this post, but good catch :-) https://www.jpl.nasa.gov/edu/news/2016/3/16/how-many-decimals-of-pi-do-we-really-need/ https://www.jpl.nasa.gov/edu/news/2016/3/16/how-many-decimal...
- johnrackles 4y ago
  Thats an interestring post, thank you! Do you think that's why for example JavaScripts Math.PI also comes out to 3.141592653589793?
  - 4y ago

samlittlewood 4y ago

It might be interesting to explore with the students why this would not be quite right for a general 3D view, and how it could be fixed. Conic sections, etc.

spuz 4y ago

I'm just getting my feet wet with shaders myself. Could this fragment shader be used in a "real" 3D game? At the moment, the sphere is orthographicly projected onto the screen so the sphere will always appear as a circle rather than an ellipse. How easy would it be to use this shader in place of a spherical mesh as you might find in a typical geometry based 3D render? I.e. could you use the same technique and render multiple balls on the screen with positions in 3D space and rendered correctly taking into account any distortion caused by the camera?

Sharlin 4y ago
It could be used as a sprite that looks like real geometry with some tweaking.
Zinu 4y ago
I'm also new to shaders, so I might be wrong: Camera distortion (/perspective) is done in the vertex shader, this post here presents a fragment shader. So if you take a quad, in the vertex shader then rotate it so it'll face the camera (i.e. all vertices have same z/depth value in clip space), you can then probably use this fragment shader to render the ball. You have to rotate the quad to face the camera, since it has to cover the area where the ball may render (imagine the extreme case: if the quad is perpendicular to the camera, it looks like a line to the camera, you could only render the ball within that line, it wouldn't protrude to the left or right).
- Doxin 4y ago
  > You have to rotate the quad to face the camera Or you only run the center point through the camera transform, and then render the quad in screen space. Should be cheaper in terms of compute.
sysrpl 4y ago
It can be incorporated into a 3D scene as long as you can make a square billboard . You may have problems with clipping that' you need to address manually, but it might be worth it as you can get better visuals, assuming you are trying to render spheres. As far as I know there shouldn't be any distortion issues. A sphere will always look like a circle from any perspective. Well that is unless it's really really big or your are really really tiny and you give the size difference you are relatively close to its surface. At that perspective it just look like a flat plane.

halaiis 4y ago

This reminds me of the same rendering technique described in Hustle Kings for the PS3. There was a write up done, however shader code was not included. https://web.archive.org/web/20130913033312/http://www.voofoostudios.com/?p=33 https://web.archive.org/web/20130913033312/http://www.voofoo...

sysrpl 4y ago
That's very interesting. Thank you for the link. From what I read and see in the images, I gather he's done the same thing I have, as you guessed as well. Obviously he's going much further. The author is using a subtle bump map (simulating balls scratches and imperfections), a reflection map with a gradient and indecent angle, what looks to be a faux sub surface scattering effect. Also he is placing his balls in a 3D environment with nice shadows that really help to sell the illusion. That's a good find and an interesting read. Thank you.

the__alchemist 4y ago

Good timing - I was procrastinating on HN instead of trying to fix my phucked-up phong; you've helped me do both.

sysrpl 4y ago
With a good phong it's all about the dot products and specular highlight (if you using highlights). Make sure you clamp the dot products and give yourself a minimum ambient light value of around 0.15 to 0.2.
Jasper_ 4y ago
The thing that got me, in a classic Phong, you have to test whether dot > 0.0, it really won't work outside of the front hemiphere. The clamp isn't enough.

benj111 4y ago

Fyi. "Rendering my balls" says something very different to "rendering balls". Although the hair would be impressive if you managed to do it. (Testicles btw)

silverfox17 4y ago
I believe they titled it that way on purpose.
hermitcrab 4y ago
(Testes btw)
- benj111 4y ago
  I like how you can confidently correct me over the hyper precise term 'balls'. Even though the term 'balls' generally includes the sack (and hair) which neither of us accounted for.

noam_compsci 4y ago

Risky click of the day

gitgud 4y ago

Very nice! not sure if you've heard of [1] ShaderToy, but it's pretty good for sharing/viewing shaders online. [1] https://www.shadertoy.com/ https://www.shadertoy.com/

gfody 4y ago
https://www.shadertoy.com/view/XlfBRH https://www.shadertoy.com/view/XlfBRH https://www.shadertoy.com/view/MtlGD8 https://www.shadertoy.com/view/MtlGD8

rawoke083600 4y ago

The sexes(including all modern derivatives) may really be equal, but I for one truley enjoyed this title submitted most likely by a male :p

acqbu 4y ago

To me, those balls are perfect

MaxBorsch228 4y ago

I guessed correctly by the title that the article is about coding a 3d image, but was waiting for the classic "two balls and a cylinder" scene, which college students naturally come up with in path tracing assignment in computer graphics courses.

virtualritz 4y ago

In the 90's, texture maps were a luxury for anything. As a result shaders (for offline rendering, realtime shading languages didn't exist yet) were doing everything procedurally. Here is the only image I could find of the RenderMan Shading Language VIDI SPORTS SHADERS Makina Works sold at the time (you got no source, just bytecode understood by Pixar's implementation at the time, AFAIK): https://web.cs.wpi.edu/~matt/courses/cs563/talks/renderman/SportsBalls.jpg https://web.cs.wpi.edu/~matt/courses/cs563/talks/renderman/S... What is interesting here is that the shaders did everything on a sphere primitive. All RenderMan implementations at the time (there were more than just Pixar's) were micropolygon renderers. I.e. displacement was almost free in terms of compute overhead. Even the football operated on a sphere that the shader deformed into the resp. shape. All patterns, stripes etc. were procedurally generated. Each shader had texture slots to apply custom logos.

ricardobayes 4y ago

Even after 10 years I still have anxiety looking at OpenGL code. I still don't understand why we needed to write ray-tracing during a BSc course starting from a blinking cursor. The professor tried to defend that at the time, but I firmly believe that it is the wrong curriculum for a 20 year old CS student. Computer graphics were and are niche programming, and should not be taught main-stream. Out of 100 graduates maybe one will ever use this, why not use some common sense and teach something useful?

skywal_l 4y ago
Because graphics is fun. It's a good way to engage with students. Beside, what's important is not the outcome but the journey. You learn to read documentation, to design, to debug and more importantly you learn to learn. Which is what higher education is about.
NavinF 4y ago
inb4 you get 10 replies along the lines of "wow I wish my professors let me do something cool like ray-tracing. I spent 4 years implementing cache-inefficient data structures that nobody uses in an ancient version of some programming language that nobody uses in a crappy env doesn't even have a real debugger" Not that I can relate. I dropped out of uni well before I encountered anything that would discourage me from going into software :)
npteljes 4y ago
Education is about exercising the mind. I don't think many play with inflated balls in their adulthood, yet it's very important to teach children hand-eye coordination, team play, and other concepts so that they become better functioning humans. There are problems with the curriculum though, one of them that it plays catch-up with the state of the world. IT in particular moves very fast. Graphics programming is not one of these things however. For example, if you've done the courses, and experiences just how hard it is to crate anything in 3d, you can better appreciate the work that goes into modern 3d engines. Look at this beautiful breakdown of the inner workings of the GTA V engine: http://www.adriancourreges.com/blog/2015/11/02/gta-v-graphics-study/ http://www.adriancourreges.com/blog/2015/11/02/gta-v-graphic...

deleted 4y ago

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drzel 4y ago

not sure about that red 10-ball tho.

pupppet 4y ago

Pretty interesting how he's wrapping the text before the curved image on the right.