HLSL Renderer

Aquarium's visible world is currently a D3D12 HLSL renderer with a small, explicit frame graph.

Current Path

D3D12Grid.hlsl renders a 128x128 scalar Grid height target.
D3D12Scene.hlsl traces the Self emitter, planets, cursor locator, and Grid event lane into scene-linear HDR targets.
D3D12Post.hlsl builds bloom, resolves diagnostics/history, applies exposure and ACES, then presents.
DirectWriteOverlay draws crisp final-pixel debug UI after scene rendering.

C# feeds explicit frame constants: resolution, time, Grid radius, camera position, presentation controls, previous frame state, cursor anchors, and debug mode. CultMath is the CPU-side math grammar. Vortice math stays at the graphics API membrane.

Grid

The Grid height target is centered on the camera target; body anchors remain in world space. The target stores height in .r only. A future useful expansion is packed gradients in .g/.b if normal cost becomes worth the extra bandwidth.

Grid linework is derivative-aware in the final scene pass. Cartesian lines use screen-space fwidth against their world-domain coordinate so minor and major lines stay the same pixel width across zoom distances. Terrain isolines derive from the Grid height field, while field lines quantize terrain gradient angle and fade out on flat surfaces.

The Grid is not an opaque surface. The scene shader traces it before the nearest solid and emits premultiplied event radiance plus event metadata. The opaque surface packet belongs to Self, planets, cursor, or empty space.

Solids

Self and planets are analytic sphere hits. The cursor is a revolved MathWorld teardrop SDF with SDF ripples and brass GGX material. It carries current and previous cursor world anchors so temporal reprojection can account for object motion.

Lighting is currently direct and diegetic: Self is the emitter. No ambient fill is allowed to quietly solve a bad light story.

Temporal Diagnostics

The temporal resolver is documented in docs/tsr-inspired-taa-spec.md. The live frame currently keeps history and control targets for inspection and future work, but projection jitter is disabled and final presentation favors current truth over stale history.

Debug modes:

0 final
1 raw current scene
2 reprojected history sample
3 history age
4 history weight
5 current temporal control
6 current field identity
7 bloom contribution
8 exposed luminance

F1 cycles modes. Number keys select the first modes directly. Startup mode can be set with --render-debug or AQUARIUM_RENDER_DEBUG_MODE.

HDR

Presentation applies explicit exposure before display transformation and adds a low-gain pre-tonemap bloom/veil pyramid. The bloom pass renders exposed scene-linear HDR color into half-, quarter-, and eighth-resolution targets, uses firefly-safe downsampling, blurs each level with separable horizontal/vertical passes, then contributes gently before the ACES fit. This is not threshold glow.

Overlay Text

Readable overlay text is handled by DirectWriteOverlay, using DirectWrite for font layout/rasterization and Direct2D for final draw. D3D12 reaches that path through D3D11On12 only after the scene frame is rendered. The bridge is overlay-only.

The debug controls live in Render/Ui/DebugUi.cs. The grammar is a native version of CultLib's generator API: panels, sections, sliders, toggles, options, and buttons are declared in code and bound to engine state with explicit read and write delegates. The visual language is compact, flat, and allowed to have taste. Frighteningly controversial, apparently.

The overlay owns a private DirectWrite font collection built from bundled Google Fonts files in Assets/Fonts: Montserrat for thin small-cap display text and Ubuntu Sans for body/debug copy. Runtime must not depend on system-installed fonts.

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