Hello,
short story: I wanted to start to implement OSL maps into our shading pipeline to live a long, relaxed life, but I did some very simple tests. After I noticed massive slowdowns with even just an OSL color node, I started to test different corona maps too, to find out if this problem only connected to OSL or not.
It's seems Corona maps can heavily affect render times, even if they are basically do nothing at all.
How I did the tests:
- almost all of the maps was "turned off", no default parameters are changed, I expected that they should act as a pass-thru node or just output a single color. Connected to the diffuse slot.
- with bitmaps
- with disable shading(render only masks) and CShading Source(RAW)Color: diffuse, bitmap sampling turned off, with nearest-neighbor and others in the bitmap sampling(because of the OSL text. loader)
- with environment maps: single bacgkround color(no map), single coronaColor node, coronaBitmapHDRI in a very simple leftover of an interior scene
- in the diffuse, glossiness and reflection color slots of CoronaMtl
Recreate the problem:
Sample scenes are attached(2019), materials and nodes are in SME. Everything is super simple.
You can test to render the scene with only connect a CoronaColor to the diffuse and compare it with adding a CoronaColorCorrect after the color, don't change the defaults(does nothing in this state), render time is doubled.
I tested it with many possible combinations, with many nodes like CoronaColor+someNode, connected to diffuse or env.
- When I used a CoronaColor(white)+CoronaColorCorrect in the env. slot and in the diffuse, rendertime is tripled.
- If there is a Corona ColorCorrect only in the environment map,
no less slowdown.
- It affects the diffuse and reflection color but not the glossy or bump channel
Attached some test renders, I hope the filenames are understandable.
- coronaCC_speedDecrease.zip - a very simple leftover of an interior scene, model is shit
- corna_OSL_speed_v01_01.zip - disabled shading, CShading_SourceColor, you need to select the plane before render(blowup auto select region is on)
Basically almost every corona map affects render time more or less, I think much more than it could be considered acceptable. Did some simple tests in Arnold, no render time increases like these.
CoronaColorCorrect is the worst one of all the corona maps. It can slowdown rendering 2-3 times. General OSL nodes 2 times slowdown, TextureLoader is the slowest OSL.
Ohh, by the way, multiplied CoronaCC train is multiplying slowdown, however OSL nodes are not, it seems they are only triggering something sensitive stuff. Check the last picture, fun.
I was able to do 30 x longer render times with a few CoronaColorCorrect nodes doing nothing. :)
I pretty hope you will fix this in a hotfix together with the OSL slowdowns.
Please let me know if something is unclear or I wrote some bullshit in this f****g too long post.
Corona 4.1, Max 2019.3(2020 too), multiple dualXeon machines, win10
ps.: I found this old topic about OSL trace() call, I guess you know it's fixed in 2020(OSL APT for 3rd party renderer dev include OSL trace() function call).
https://forum.corona-renderer.com/index.php?topic=20128.msg125617#msg125617
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