BD GLSL Batch (iterate uniforms)

Say you've built a GLSL skin-tint shader and you want to see it under five different lighting uniforms - or generate every variant of a texture atlas in one go. The dumb way is to re-run the workflow five times, recompiling the shader each time. The smart way is BD_GLSLBatch: it runs the same shader N times with different uniform values inside a single node call, compiles the shader once, and stacks the outputs along the batch dimension.

This is the batch-oriented cousin of the pack's single-shot GLSL shader node (the one behind the GLSL Skin Tinting template, with its ILM / SR+Parts / Unity / Unreal output quads). Where that node gives you one pass, this one gives you a batch - perfect for iterating skin tones, LUT variants, or any uniform sweep you'd otherwise hammer the queue with.

How it works

You supply the shader as a GLSL ES 3.0 fragment source (or point fragment_shader_file at an absolute path to a .glsl file, which is great for editing externally - the node picks up the latest version on each execution). It binds up to five images (u_image0..u_image4) as samplers, plus base uniform values via the floats and ints fields, one per line: u_float0=0.48, u_int0=255.

The per-iteration variation lives in vary_floats and vary_ints, using the same syntax but with comma-separated lists:

u_float0=0.5,0.4,0.3,0.2
u_int3=255,240,160,140

Iteration count is auto-detected from the longest vary list. Uniforms not listed in a vary spec keep their base value every iteration; single-value lines act as constants. iterations_override forces a count if you want control, and width/height set output resolution (0 = take u_image0's size).

Outputs

• fc0_batch / fc1_batch / fc2_batch / fc3_batch - the four fragment-color outputs, each stacked into an IMAGE batch of N_iterations. The fc naming matches the pack's GLSL convention (multiple render targets).
• iteration_names - one name per iteration (from the iteration_names field) for downstream filename use, newline-joined.
• iteration_count - how many iterations actually ran.

iteration_names is the detail that makes this usable: name your iterations light\nmedium\ndark\nzombie, then feed the names batch into a save node's suffix logic so every batch frame gets a sensible filename.

Install

Part of the BrainDead pack:

cd ComfyUI/custom_nodes
git clone https://github.com/BizaNator/ComfyUI-BrainDead
cd ComfyUI-BrainDead
pip install -r requirements.txt

Or search "BrainDead" in ComfyUI Manager and restart. This is one of the heavier corners of the pack to get running - it needs a working GPU shader runtime, so if the pack's GLSL nodes fail on your setup, the single-shot GLSL node is the first thing to test.

Troubleshooting

• Wrong iteration count - count your vary lists. The node takes the longest; a stray longer list silently changes N.
• Batch frames all look identical - a uniform you meant to vary isn't in a vary spec (or is a single-value line, which is constant by design).
• Shader file edits don't appear - fragment_shader_file only overrides when the path exists; double-check it's absolute and on disk.