SSAO

[ffreyer]

Based on the learnopengl tutorial Simon posted in MakieOrg/Makie.jl#487

I believe SSAO is fully working at this point, but it's a very hacky implementation. I thought this would be a good point to get some feedback though, specifically on how connect this to GLMakie correctly.

Rough TODO

• Pass projection in a less hacky way
• Make things controllable using Makie attributes. (How would I go about this? They aren't directly available when creating the Framebuffer...) This includes:
  • number of SSAO samples (requires shader recompilation - how?)
  • bias (minimum depth difference for pixel to be occluded)
  • radius (distance checked for occlusion)
  • blur (related to number of pixels used in blur)
  • maybe some controls for randomness of noise and samples
• on/off switch for SSAO
• implement deferred shading (i.e. move light calculations to postprocessing) (not doing this results in a weird glowing effect) (nvm, the glow is a result of blurring)
• fix background getting darkened (when there is no geometry)
• allow SSAO to run w/o FXAA
• fix lighting
• fix glow
• replace render_colorbuffer

---

Here are some pics:
cat w/o SSAO:

cat w/ SSAO

cat w/ only SSAO

[SimonDanisch]

Yeah we shouldn't calculate this in the shader ;)

[ffreyer]

I added some code to generate a normalmatrix in cached_robj!()

[SimonDanisch]

Awesome :) On first sight, this looks pretty similar to how I'd have done it ;)

[ffreyer]

I think I got SSAO working correctly for multiple scenes now. Took me quite a while to figure out why it wasn't working. I wrote a longer comment in the shader that explains what I'm doing and why I'm doing it.

Current cat(s):

[ffreyer]

I made this clear color a jarring pink so I can see if it ever appears. Should be removed or set to white before merging. There's another one of these further down (using green)

[ffreyer]

Pink becomes visible if bias < 0.

[ffreyer]

Do these require a v /= v.w?

[ffreyer]

Alternatively, we could also do

o_normal = normal_model_matrix * normal;
o_view_normal = normal_view_matrix * normal; // pass this to SSAO
o_lightdir = normalize(lightposition - position_world.xyz);
o_camdir = normalize(eyeposition - position_world.xyz);
o_view_pos = view * position_world; // pass this to SSAO
gl_Position = projection * o_view_pos;

where the normal matrices are transpose(inv(view) and tranpose(inv(model)). Not sure which is better...

[ffreyer]

using Colors, Makie
s1, radius = textslider(0.0f0:0.1f0:2f0, "Radius", start = 0.5f0)
s2, bias = textslider(0f0:0.005f0:0.1f0, "Bias", start = 0.025f0)
s3, blur = textslider(Int32(0):Int32(1):Int32(5), "Blur", start = Int32(2))
ssao_attrib = Attributes(radius=radius, bias=bias, blur=blur)

ps = rand(Point3f0, 100)
colors = rand(RGB, 100)
scene1 = meshscatter(ps, color=colors, ssao=true, SSAO=ssao_attrib)
scene2 = meshscatter(ps, color=colors, ssao=false) # default
hbox(vbox(s1, s2, s3), vbox(scene1, scene2))

Here's a little example for playing around with attributes. The left side uses SSAO, the right side doesn't. Depending on the colors the shine/glow issue is quite noticeable here, and by modifying blur (which sets the pixel-range for blurring) you can see that it is connected to that.