37177a418e
Retail-anchored design for the missing visual feedback on selection:
four corner triangles + radar-blip colour coding around the selected
entity, drawn via ImGui in screen space.
Retail evidence (named decomp):
* VividTargetIndicator::SetSelected at 0x004f5ce0
* gmRadarUI::GetBlipColor at 0x004d76f0 (Portal / Vendor / Creature /
Player / PK / PKLite / Default colours from pwd._bitfield bits +
IsCreature/IsPlayer/IsPK predicates we already parse)
* VividTargetIndicator::CopyImage at 0x004f5dd0 (tints a source
bitmap by RGBA)
MVP scope:
1. RadarBlipColors helper (Core, with unit tests)
2. TargetIndicatorPanel (App, ImGui draw via background draw list)
3. Wire to existing _selectedGuid from B.4b
4. ~200 LOC + tests
Deferred to follow-ups: off-screen edge arrow, DAT-loaded sprite (MVP
draws procedurally), mesh-tint highlight, player-option toggle, server
selection-relay.
Pairs with #59 (WorldPicker over-pick): the indicator makes the
mis-pick visible, so the user can clear + reselect even before the
underlying picker is tightened.
128 lines
8.1 KiB
Markdown
128 lines
8.1 KiB
Markdown
# Phase B.7 — Vivid Target Indicator — design
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**Date:** 2026-05-15.
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**Status:** DESIGN — implementation starting same session.
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**Closes (partially):** [issue #59](../../ISSUES.md) (`WorldPicker` over-pick — by making the wrong pick *visible* so the user can correct before clicking).
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**Predecessors:** B.4b (selection), B.5 (pickup), B.6 (auto-walk).
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**Retail anchors (decomp `docs/research/named-retail/acclient_2013_pseudo_c.txt`):**
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- `VividTargetIndicator::SetSelected` at `0x004f5ce0` — selection setter + filtering.
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- `gmRadarUI::GetBlipColor(weenie)` at `0x004d76f0` — per-type colour table.
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- `VividTargetIndicator::CopyImage` at `0x004f5dd0` — tints a source bitmap by RGBA, four blit methods supported.
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- `VividTargetIndicator::UpdateDisplayState` at `0x004f5fb0` — gated on `PlayerOption_VividTargetingIndicator`.
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- Two render surfaces: `m_pOnScreen` (corners around target) + `m_pOffScreen` (edge arrow when target is off-camera).
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---
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## Problem
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User sees `Tirenia` chat dialogue after intending to click an item. Cause: `WorldPicker.Pick`'s 5 m fixed radius over-picks bigger collision spheres (NPCs > items). Without on-screen feedback, the user can't tell their intended click missed — they only see the consequence (NPC walks toward, dialogue fires).
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Retail solved this with **selection feedback** drawn over the 3D scene: four small corner triangles framing the target's silhouette, colour-coded by entity type (yellow ≈ creature, white ≈ default, red ≈ PK, etc.). The mere existence of the indicator makes the picker bug self-correcting — you click empty space to deselect, then click again on the actual target.
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This is the *missing UX feedback* that's been silently breaking interaction since B.4b shipped.
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---
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## Scope decisions
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**Included in B.7 MVP:**
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1. Per-entity colour lookup, port of `gmRadarUI::GetBlipColor` using our existing `ItemType` and `ObjectDescriptionFlags` (already parsed from `CreateObject`).
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2. Screen-space corner-triangle renderer drawn via ImGui's `ImDrawList` (we already have ImGui — no new GL infrastructure).
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3. Hook to `_selectedGuid` — updates whenever B.4b's `PickAndStoreSelection` mutates the selection.
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4. Hidden when no selection, or when the selected entity is no longer in `_entitiesByServerGuid` (despawned).
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**Deferred to B.7 follow-ups:**
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- Off-screen edge arrow (`m_pOffScreen`). Useful for tracking a target you walked past; not MVP-critical.
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- Retail-faithful corner-triangle imagery loaded from the DAT. MVP draws procedurally-coloured equilateral triangles via ImGui — looks acceptable, doesn't need a DAT-asset hunt.
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- Mesh-tint highlight (`"texture lights up a bit"`). That's a shader-level change on the selected entity's mesh. Requires touching `WbDrawDispatcher` to flag a per-instance highlight uniform. Two-line stub already mentioned in the `mesh_modern.vert` `InstanceData` struct docstring (per CLAUDE.md WB integration cribs) — pick it up if the corner triangles aren't enough.
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- Player-option toggle (`PlayerOption_VividTargetingIndicator`). MVP is always-on; add toggle if users complain about screenshots.
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- Server selection-relay (`SmartBox::SetTargetObjectID` outbound, `RecvNotice_ServerSaysMoveItem` inbound). Not visible in current ACE behaviour and not blocking M1.
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---
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## Architecture
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Single new file: `src/AcDream.App/UI/TargetIndicatorPanel.cs` (or similar — fits the existing `AcDream.UI.Abstractions.Panels.*` pattern but lives in `AcDream.App` because it touches `GameWindow`'s camera projection state).
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**Responsibilities:**
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- Read `_selectedGuid` (passed in via constructor delegate, like the existing `DebugVM` wiring).
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- Look up the entity in `_entitiesByServerGuid` + `_liveEntityInfoByGuid`.
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- Compute world-space AABB centre + radius (use cached `EntitySpawn.ItemType` for type bits + a fixed visual radius — 1 m default, or per-itemType later).
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- Project the AABB to 4 screen-space corner positions using the active camera's `View × Projection × Viewport`.
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- Resolve colour via `RadarBlipColors.For(itemType, objectDescriptionFlags)` — new static helper class.
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- Draw 4 small filled triangles via `ImGui.GetBackgroundDrawList().AddTriangleFilled`.
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**Render order:** background-draw-list, AFTER the 3D scene, BEFORE other ImGui panels so other UI can occlude the triangles if needed.
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---
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## Colour table
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Per `gmRadarUI::GetBlipColor` decomp lines `219913+`, the dispatch order is:
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```
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if pwd._bitfield & 0x40000 → Portal (cyan-ish?)
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if pwd._bitfield[1] & 0x02 → Vendor (green?)
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if (pwd._bitfield & 0x10) && IsCreature && !IsPlayer → Creature (yellow)
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if IsPlayer:
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if IsPK → PlayerKiller (red)
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elif IsPKLite → PKLite (pink?)
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elif pwd._bitfield & 0x200000 → Creature-coloured (hostile player flag?)
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else → Default (white)
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… (more branches above the read window)
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```
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I'll port the dispatch verbatim. The actual `RGBAColor_Radar*` constants live in retail data (probably in `acclient.h` per CLAUDE.md's named-retail anchors). For MVP I'll use hand-picked colours that visually match retail screenshots; refine later if I find the constants.
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---
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## Triangle geometry
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Each corner triangle in retail is a small right-angle triangle pointing *into* the centre of the selection rectangle — i.e., the top-left corner has its hypotenuse along the screen-up-then-screen-right diagonals, pointing down-right toward the entity. Same pattern at the other three corners (rotated 90° / 180° / 270°).
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MVP: small filled triangles (~8 px legs) at each corner of the projected AABB, oriented inward. Fine-tune via screenshots vs retail later.
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---
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## File-level scope sketch
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- **New:** `src/AcDream.Core/Ui/RadarBlipColors.cs` (`AcDream.Core` so it's testable independently of `App`). Static class with `RGBA For(ItemType, ObjectDescriptionFlags)` returning a tagged colour. ~60 LOC.
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- **New:** `src/AcDream.App/UI/TargetIndicatorPanel.cs` (~100 LOC). Owns the per-frame projection + ImGui draw. Constructor takes:
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- `Func<uint?> selectedGuidProvider`
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- `Func<uint, EntitySpawn?> entityResolver` (closure over `_entitiesByServerGuid` / `_liveEntityInfoByGuid`)
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- `Func<(Matrix4x4 view, Matrix4x4 projection, Vector2 viewport)> cameraProvider`
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- **Modify:** `src/AcDream.App/Rendering/GameWindow.cs` (~15 LOC). Construct the panel after ImGui init, wire delegates, call `Render()` from the ImGui pass.
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- **Tests:** `tests/AcDream.Core.Tests/Ui/RadarBlipColorsTests.cs` (~40 LOC, 5-6 cases covering the type-flag → colour matrix).
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Total ~200 LOC + tests. Single phase, no slices needed.
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---
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## Acceptance criteria
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- [ ] Single-click an NPC at Holtburg → yellow-ish corner triangles appear around it.
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- [ ] Single-click a ground item → white-ish triangles.
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- [ ] Click empty ground / deselect → triangles disappear.
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- [ ] Selected entity moves → triangles track it (project per frame).
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- [ ] Selected entity despawns → triangles disappear.
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- [ ] No measurable FPS regression at Holtburg radius=4 (it's 4 triangles per frame — should be invisible to perf).
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- [ ] Unit tests cover the colour-lookup matrix: NPC, item, player, PK, lifestone, portal, vendor.
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---
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## Out of scope (deferred)
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- Off-screen edge arrow.
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- DAT-loaded triangle sprite (procedural for MVP).
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- Mesh-tint highlight on selected entity.
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- Player-option toggle.
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- Server selection-relay (`SmartBox::SetTargetObjectID`).
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- Tab-cycle selection (`SelectClosestCombatTarget` already exists for combat; non-combat cycle is a separate UX phase).
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---
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## Out-of-band: addressing the picker over-pick (#59)
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This phase deliberately does NOT fix the underlying picker. Once the indicator is shipped, the user can *see* the wrong selection and click empty space to clear it, then retry on the actual target. The picker fix (tighter per-itemType radius, ray-test against actual mesh bounds, or click priority by itemType) is a follow-up that can be informed by which combos most often produce mis-picks once we have the indicator showing them clearly.
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If the indicator + picker need to be revisited together later, both end up in the same UX phase.
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