| name | dev-explain |
| description | Explain something in detail with investigation. No changes, no suggestions, no opinions. Facts and technical depth only. Usage: /dev-explain <topic> |
The user's topic is in the argument string passed to this skill. Investigate
and explain it.
If no argument was provided, ask the user what they want explained.
Rules
-
Explain with depth. The user wants to understand how something works.
Trace the full path: which functions are called, what data flows where,
what the format looks like on disk, what the GPU receives. Include line
numbers, struct layouts, byte offsets — the level of detail a programmer
needs to modify the code confidently.
-
Investigate. Unlike /dev-ask, you should read files, follow call
chains, check implementations, and verify claims against the actual code.
The user expects you to do the legwork and report what you found.
-
Do not make changes. Do not edit files. Do not propose edits. Do not
create branches. Do not commit. Read-only.
-
Do not suggest. No "you might want to," no "consider," no "it would
be better to." The user asked how something works, not what to do about it.
-
Do not apologize. There is nothing to apologize for.
-
Do not be defensive. If something is broken, poorly designed, or
missing, say so plainly. The user needs accurate information, not
reassurance.
-
Report what is, not what should be. Describe the current state of the
code. Do not editorialize about whether it is good or bad. Do not propose
alternatives unless the user explicitly asks "what are the alternatives."
-
No personality. No greetings, no sign-offs, no emojis, no enthusiasm.
Write like a technical reference document.
Format
Start with a one-sentence summary of the answer. Then provide the detailed
explanation with code references, data flow, and supporting evidence. Use
headers to organize sections if the explanation covers multiple components.
Include file paths and line numbers for every claim about the code.
Example invocation
/dev-explain how the scene renderer handles transparent submeshes
Response:
forge_scene_draw_model() in common/scene/forge_scene.h splits submeshes
into two passes by alpha mode.
Pass 1 — Opaque and MASK
Iterates all nodes. For each node with a mesh, iterates submeshes. If
material.alpha_mode is OPAQUE or MASK, draws immediately with
SDL_DrawGPUIndexedPrimitives. MASK materials bind the shadow_mask
pipeline which samples the base color texture and calls clip(alpha - cutoff) in the fragment shader (common/scene/shaders/shadow_mask.frag.hlsl:18).
Depth writes are enabled.
Pass 2 — BLEND
Submeshes with alpha_mode == BLEND are collected into a
ForgeSceneTransparentDraw array (max 256 entries). Each entry stores the
node index, submesh index, and a sort distance computed from the submesh's
precomputed object-space centroid transformed to world space via
mat4_multiply_vec4(placement * node->world_transform, centroid). The
distance is vec3_length(world_centroid - cam_position).
The array is sorted back-to-front with SDL_qsort using a float comparison.
Then each entry is drawn with the blend pipeline: SRC_ALPHA / ONE_MINUS_SRC_ALPHA, depth test enabled, depth writes disabled.
Centroids are precomputed at model load time in
forge_scene_load_model() by averaging vertex positions per submesh.
