Completely black renders

[shankarsivarajan]

I tried rendering the default startup scene (Blender 3.0.1, Windows 10), and the render is all black. It didn't raise any errors though, and increasing the intensity of the light didn't seem to do anything. Could you please share an example of a scene that works for you?

[bsavery]

https://github.com/bsavery/BlenderPythonRenderer/tree/main/examples

Can you open the blender system console and see if there's any errors there?

[shankarsivarajan]

No errors, but on the first render there is a warning:

[Taichi] version 0.9.0, llvm 10.0.0, commit 0c432a37, win, python 3.9.7
call setup
[Taichi] Starting on arch=cuda
Total export 3.584152936935425
[W 02/22/22 20:26:47.050 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$6896] Local store may lose precision (target = u8, value = u8), at
6896
[W 02/22/22 20:26:47.052 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$7127] Local store may lose precision (target = u8, value = u8), at
7127
[W 02/22/22 20:26:47.053 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$7687] Local store may lose precision (target = u8, value = u8), at
7687
[W 02/22/22 20:26:47.053 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$9019] Local store may lose precision (target = u8, value = u8), at
9019
[W 02/22/22 20:26:47.055 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@67] [$10257] Atomic add (i32 to u32) may lose precision, at

[W 02/22/22 20:26:47.062 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$6896] Local store may lose precision (target = u8, value = u8), at
6896
[W 02/22/22 20:26:47.063 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$7127] Local store may lose precision (target = u8, value = u8), at
7127
[W 02/22/22 20:26:47.065 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$7687] Local store may lose precision (target = u8, value = u8), at
7687
[W 02/22/22 20:26:47.069 5224] [D:/a/taichi/taichi/taichi/transforms/type_check.cpp:visit@142] [$9019] Local store may lose precision (target = u8, value = u8), at
9019
Total render 12.15920352935791

Subsequent renders don't have this.

call setup
Total export 1.9710016250610352
Total render 9.001036882400513

[shankarsivarajan]

What version of taichi are you using?

[bsavery]

I have 0.8.X (I think 0.8.6) I haven't tested with taichi 0.9.0 yet.

Also this line https://github.com/bsavery/BlenderPythonRenderer/blob/6d7ff4e5ee7cf69bded451399877d12e15ed9936/render/render.py#L31

Can be set to use ti.vulkan or ti.cuda I think depending on your GPU. Might make a difference.

[shankarsivarajan]

The example scenes both work as expected with Blender 3.5, Taichi 1.5, on Windows 10.

The problem was that I didn't have a light in the scene: the default point light is not recognized. I needed to add a mesh object, and add a Principled shader with emission before changing the render engine to BPR. I also needed to close and reopen the file before rendering.