acdream/src/AcDream.App/Rendering/ChargenPreviewCamera.cs

using System;
using System.Numerics;
using AcDream.Core.CharGen;

namespace AcDream.App.Rendering;

/// <summary>
/// Heritage-parameterized camera for the chargen 3D preview
/// (<c>gmCG3DView</c>, Appearance page viewport <c>0x100003bb</c> / Summary
/// <c>0x10000406</c>). Retail-exact eye positions, ported from
/// <c>gmCGAppearancePage::Update @ 0x0047E8F0</c> (pseudo-C ~139037-139114,
/// which sets <c>m_vectTargPosition</c>/<c>m_vectCurPosition</c> per
/// heritage and snaps them together with no tween — CC6a's static preview
/// renders that snapped default, the "zoomed-in" framing) and cross-checked
/// against the IDENTICAL literals in <c>gmCGAppearancePage::ZoomIn @
/// 0x0047CF00</c> (pseudo-C ~137618-137638). Direction is always
/// <c>(0,0,0)</c> ⇒ <c>CreatureMode::SetCameraDirection</c> resets the view
/// frame to IDENTITY — the SAME zero-yaw/zero-pitch convention
/// <see cref="DollCamera"/> already established for the paperdoll (look
/// straight down +Y, +Z up); every camera position below is used AS the
/// world-space eye directly, matching that camera's approach.
///
/// <para>
/// <b>Rotation is NOT a camera property.</b> Retail's continuous-rotation
/// button (<c>gmCGAppearancePage::DoRotation @ 0x0047CA80</c>) advances a
/// HEADING applied to the preview CHARACTER (<c>CPhysicsObj::set_heading</c>
/// inside <c>gmCG3DView::Update</c>, pseudo-C ~242088) — the camera's own
/// position/direction never change during a rotation. The heading itself
/// lives on <see cref="ChargenPreviewRotationController"/> (CC6b: the
/// <c>DoRotation</c>/<c>Rotate</c> port) and is applied to the entity via
/// <c>ChargenPreviewEntityBuilder.TryBuild</c>/<c>TryBuildAnimated</c>'s
/// <c>heading</c> parameter, not here; this class stays a fixed-per-heritage
/// eye, exactly like retail's own camera. <see cref="ChargenPreviewZoomController"/>
/// (CC6b: the <c>ZoomIn</c>/<c>ZoomOut</c>/<c>DoZoomAnimation</c> port) DOES
/// mutate this class's <see cref="Eye"/> — zoom is a camera concern, unlike
/// rotation.
/// </para>
/// </summary>
public sealed class ChargenPreviewCamera : ICamera
{
    private static readonly Vector3 Up = Vector3.UnitZ; // AC up-axis = +Z, same as DollCamera/ChaseCamera.

    private Vector3 _eye;

    public ChargenPreviewCamera(uint heritageId = 0u)
    {
        _eye = ResolveDefaultEye(heritageId);
    }

    /// <summary>
    /// The camera's current world-space eye. Settable so CC6b can react to a
    /// heritage change without reconstructing the camera.
    /// </summary>
    public Vector3 Eye
    {
        get => _eye;
        set => _eye = value;
    }

    /// <summary>Re-derives <see cref="Eye"/> for the given heritage id (retail's <c>mHeritageGroup</c>).</summary>
    public void SetHeritage(uint heritageId) => _eye = ResolveDefaultEye(heritageId);

    /// <summary>
    /// Retail default (zoomed-in) camera eye per heritage. All four profiles
    /// share <c>X=0</c>; only <c>(Y, Z)</c> — the AC world-space forward
    /// offset and height — vary. FOUR distinct profiles across the 13
    /// heritages, not five: standard heritages (Aluvian, Gharu'ndim, Sho,
    /// Viamontian, Shadowbound, Gearknight, Lugian, Empyrean, Penumbraen,
    /// Undead — everything except Tumerok/Olthoi/OlthoiAcid) share the SAME
    /// numeric offset as Gearknight's own dedicated branch in the decomp.
    /// </summary>
    public static Vector3 ResolveDefaultEye(uint heritageId) => heritageId switch
    {
        (uint)ChargenHeritageGroup.Olthoi => new Vector3(0f, -1.85000002f, 1.85000002f),
        (uint)ChargenHeritageGroup.OlthoiAcid => new Vector3(0f, -3.04999995f, 2.75f),
        (uint)ChargenHeritageGroup.Tumerok => new Vector3(0f, -0.850000024f, 1.64999998f),
        _ => new Vector3(0f, -0.550000012f, 1.64999998f),
    };

    /// <summary>
    /// Retail zoomed-OUT camera eye per heritage
    /// (<c>gmCGAppearancePage::ZoomOut @ 0x0047D050</c>, pseudo-C
    /// ~137671-137687). CC6a does not implement the zoom button (CC6b) —
    /// recorded here as the verified target CC6b's tween will animate
    /// toward. Olthoi/OlthoiAcid each keep their own dedicated profile;
    /// every other heritage — INCLUDING Tumerok, whose zoomed-IN profile is
    /// special-cased but whose zoomed-OUT is not — shares one value.
    /// </summary>
    public static Vector3 ResolveZoomedOutEye(uint heritageId) => heritageId switch
    {
        (uint)ChargenHeritageGroup.Olthoi => new Vector3(0f, -3.79999995f, 1.14999998f),
        (uint)ChargenHeritageGroup.OlthoiAcid => new Vector3(0f, -5.69999981f, 1.64999998f),
        _ => new Vector3(0f, -2.5f, 0.95f),
    };

    /// <summary>
    /// Seconds per 360° revolution for the continuous-rotation button
    /// (<c>gmCGAppearancePage::m_dRotationPerSec</c>, ctor pseudo-C
    /// ~137523-137524 / ~226652-226653: raw double bits low32=0x00000000,
    /// high32=0x40080000 → exactly 3.0 — the decompiler shows this cleanly,
    /// no reconstruction needed). Retail's own per-tick formula
    /// (<c>gmCGAppearancePage::DoRotation @ 0x0047CA80</c>, pseudo-C
    /// ~0x0047CAC7): <c>deltaDegrees = ((now - lastRotateTime) /
    /// RotationSecondsPerRevolution) * 360</c> — CC6b's rotation controller
    /// consumes this constant in exactly that shape, not as a
    /// degrees-per-second rate. NOT applied here; see this class's own doc
    /// comment on why rotation is not a camera concern.
    /// </summary>
    public const float RotationSecondsPerRevolution = 3.0f;

    /// <summary>
    /// Zoom tween duration in seconds
    /// (<c>gmCGAppearancePage::DoZoomAnimation @ 0x0047C960</c>'s
    /// reset-if-invalid default, cross-confirmed by <c>ZoomIn</c>/<c>ZoomOut</c>'s
    /// own <c>-0.1</c> sentinel write, which deliberately invalidates
    /// <c>m_dAnimDuration</c> so the very next <c>DoZoomAnimation</c> tick
    /// resets it to this same value). The campaign plan flagged this
    /// constant as decompiler-garbled (both sites split the raw double
    /// across two 32-bit stores, and the decompiler mis-renders the LOW
    /// dword's store as a bogus float literal instead of raw bits) — it is
    /// NOT unrecoverable: reinterpreting each garbled float literal as its
    /// own raw 32-bit pattern and pairing it with the store's (clean) high
    /// dword reconstructs an exact IEEE-754 double both times.
    /// <c>DoZoomAnimation</c>'s own reset path: low32 from
    /// <c>4.17232506e-08f</c> reinterpreted = <c>0x33333333</c>, high32 =
    /// <c>0x3fe33333</c> (clean) → exactly <b>0.6</b>. Cross-check via
    /// <c>ZoomIn</c>/<c>ZoomOut</c>'s sentinel: low32 from
    /// <c>-1.58818684e-23f</c> reinterpreted = <c>0x9999999A</c>, high32 =
    /// <c>0xbfb99999</c> (clean) → exactly <b>-0.1</b>, the well-known
    /// IEEE-754 bit pattern for -0.1 (<c>0xBFB999999999999A</c>) — confirming
    /// the reconstruction technique itself, not just this one value.
    /// </summary>
    public const float ZoomTweenDurationSeconds = 0.6f;

    public float FovRadians { get; set; } = MathF.PI / 4f; // retail CreatureMode default, same as DollCamera.
    public float Near { get; set; } = 0.1f;
    public float Far { get; set; } = 50f;
    public float Aspect { get; set; } = 1f;

    public Matrix4x4 View =>
        Matrix4x4.CreateLookAt(_eye, _eye + Vector3.UnitY, Up);

    public Matrix4x4 Projection =>
        Matrix4x4.CreatePerspectiveFieldOfView(FovRadians, Aspect <= 0f ? 1f : Aspect, Near, Far);
}

/// <summary>
/// Internal private-viewport adapter, mirroring <c>DollViewportCamera</c>'s
/// role for <see cref="ChargenPreviewCamera"/>.
/// </summary>
internal sealed class ChargenPreviewViewportCamera : IPrivateEntityViewportCamera
{
    private readonly ChargenPreviewCamera _camera;

    public ChargenPreviewViewportCamera(uint heritageId = 0u)
    {
        _camera = new ChargenPreviewCamera(heritageId);
    }

    public void SetHeritage(uint heritageId) => _camera.SetHeritage(heritageId);

    public Vector3 Eye => _camera.Eye;
    public float FovRadians
    {
        get => _camera.FovRadians;
        set => _camera.FovRadians = value;
    }
    public float Near
    {
        get => _camera.Near;
        set => _camera.Near = value;
    }
    public float Far
    {
        get => _camera.Far;
        set => _camera.Far = value;
    }
    public float Aspect
    {
        get => _camera.Aspect;
        set => _camera.Aspect = value;
    }
    public Matrix4x4 View => _camera.View;
    public Matrix4x4 Projection => _camera.Projection;
}