acdream/src/AcDream.App/Rendering/TerrainModernRenderer.cs
Erik f1ba147ac5 perf(vfx): port retail particle visibility degradation
Resolve DAT-authored particle ranges from the hardware GfxObj, apply retail distance and completed-cell visibility gates, and preserve the exact finite/infinite off-view update semantics. This removes dense-world simulation work without shortening terrain, entity, fog, or streaming distance.

Publish doorway-clipped outdoor cells through a focused frame controller, retain effect cell identity for outdoor statics, reject hidden emitters before particle-slot scans, and offer an explicit opt-in Extended particle range.

Release build succeeds and all 5,857 tests pass with five intentional skips. Retail-conformance, architecture, and adversarial review cycles are clean; connected Aerlinthe visual/performance gate pending.

Co-authored-by: OpenAI Codex <codex@openai.com>
2026-07-17 15:27:36 +02:00

639 lines
27 KiB
C#
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

using System.Numerics;
using AcDream.App.Rendering.Wb;
using AcDream.Core.Terrain;
using Silk.NET.OpenGL;
namespace AcDream.App.Rendering;
/// <summary>
/// Phase N.5b modern terrain dispatcher. Single global VBO/EBO with a slot
/// allocator (one slot per landblock, 384 verts × 40 bytes = 15,360 bytes
/// per slot). Per-frame: build a DrawElementsIndirectCommand array from
/// visible slots, upload, dispatch via glMultiDrawElementsIndirect. Atlas
/// textures bound via bindless handles set per-frame as sampler uniforms.
///
/// Total ~6-8 GL calls per frame for terrain regardless of visible
/// landblock count.
/// </summary>
public sealed unsafe class TerrainModernRenderer : IDisposable
{
// VertsPerLandblock MUST stay divisible by 6 — terrain_modern.vert uses
// `gl_VertexID % 6` to pick the cell-corner index (BL/BR/TR/TL), and
// because we bake `slot * VertsPerLandblock` into indices CPU-side and
// pass BaseVertex=0 to MultiDrawElementsIndirect, gl_VertexID becomes
// `slot * VertsPerLandblock + local_index`. The shader's modulo-6 only
// reduces to `local_index % 6` because 384 is a multiple of 6. Changing
// either constant without auditing the shader will silently mis-render.
private const int VertsPerLandblock = LandblockMesh.VerticesPerLandblock; // 384 (= 64 cells * 6 verts)
private const int IndicesPerLandblock = VertsPerLandblock;
private const int VertexSize = 40; // sizeof(TerrainVertex)
private const int IndexSize = sizeof(uint);
private const float LandblockSize = LandblockMesh.LandblockSize; // 192
private readonly GL _gl;
private readonly BindlessSupport _bindless;
private readonly Shader _shader;
private readonly TerrainAtlas _atlas;
/// <summary>A.5 T22.5: exposes the terrain atlas so callers can update
/// anisotropic level mid-session via <see cref="TerrainAtlas.SetAnisotropic"/>.</summary>
public TerrainAtlas Atlas => _atlas;
private readonly TerrainSlotAllocator _alloc;
// Per-slot live data (index by slot integer; null entries are unused slots).
private SlotData?[] _slots;
// Reverse map: landblockId -> slot, for RemoveLandblock and replacement.
private readonly Dictionary<uint, int> _idToSlot = new();
// GPU buffers.
private uint _globalVao;
private uint _globalVbo;
private uint _globalEbo;
private uint _indirectBuffer;
private int _indirectCapacity;
// Phase U.3: terrain clip UBO (binding=2, terrain_modern.vert TerrainClip).
// The shared one is created + uploaded by the GameWindow-level ClipFrame and
// handed in via SetClipUbo. When 0, we bind a lazily-created no-clip fallback
// (count 0 = ungated) so the shader never reads an unbound UBO at binding=2.
private uint _sharedClipUbo;
private uint _fallbackClipUbo;
// Cached uvec2-handle uniform locations (matrix uniforms are set by name via Shader.SetMatrix4).
private int _uTerrainHandleLoc;
private int _uAlphaHandleLoc;
private int _uTexTilingLoc;
private bool _textureTilingUploaded;
// Reusable per-frame buffers.
private readonly List<int> _visibleSlots = new();
private readonly HashSet<uint> _visibleCellIds = new();
private DrawElementsIndirectCommand[] _deicScratch = Array.Empty<DrawElementsIndirectCommand>();
// Diag.
public int LoadedSlots => _alloc.LoadedCount;
public int VisibleSlots => _visibleSlots.Count;
public int CapacitySlots => _alloc.Capacity;
/// <summary>
/// Outdoor landcells admitted by the current landscape view. The set is
/// accumulated across doorway landscape slices and consumed after the
/// completed render frame by particle visibility.
/// </summary>
internal HashSet<uint> VisibleCellIds => _visibleCellIds;
public void BeginVisibilityFrame() => _visibleCellIds.Clear();
public TerrainModernRenderer(
GL gl,
BindlessSupport bindless,
Shader shader,
TerrainAtlas atlas,
int initialSlotCapacity = 64)
{
_gl = gl;
_bindless = bindless;
_shader = shader;
_atlas = atlas;
_alloc = new TerrainSlotAllocator(initialSlotCapacity);
_slots = new SlotData?[initialSlotCapacity];
_uTerrainHandleLoc = _gl.GetUniformLocation(_shader.Program, "uTerrainHandle");
_uAlphaHandleLoc = _gl.GetUniformLocation(_shader.Program, "uAlphaHandle");
_uTexTilingLoc = _gl.GetUniformLocation(_shader.Program, "uTexTiling[0]");
if (_uTexTilingLoc < 0)
throw new InvalidOperationException("terrain_modern.frag is missing the required uTexTiling uniform.");
_globalVao = _gl.GenVertexArray();
_globalVbo = _gl.GenBuffer();
_globalEbo = _gl.GenBuffer();
AllocateGpuBuffers(initialSlotCapacity);
ConfigureVao();
_indirectBuffer = _gl.GenBuffer();
}
/// <summary>
/// Phase U.3: hand the renderer the SHARED terrain-clip UBO (binding=2)
/// created by <see cref="ClipFrame.UploadShared"/>. The renderer binds it to
/// binding=2 before its draw. Pass 0 to fall back to the internal no-clip UBO
/// (count 0 = ungated terrain).
/// </summary>
public void SetClipUbo(uint sharedClipUbo) => _sharedClipUbo = sharedClipUbo;
/// <summary>
/// Two-tier streaming entry point. Accepts a prebuilt mesh from
/// <see cref="LandblockStreamResult.Loaded.MeshData"/> built on the worker
/// thread, together with the world-space origin computed by the caller
/// (render-thread GameWindow derives it from landblockId + liveCenterX/Y).
///
/// Delegates to <see cref="AddLandblock(uint,LandblockMeshData,Vector3)"/>
/// so both paths share one upload path. Per Phase A.5 spec T15.
/// </summary>
public void AddLandblockWithMesh(uint landblockId, LandblockMeshData meshData, Vector3 worldOrigin)
=> AddLandblock(landblockId, meshData, worldOrigin);
public void AddLandblock(uint landblockId, LandblockMeshData meshData, Vector3 worldOrigin)
{
ArgumentNullException.ThrowIfNull(meshData);
if (meshData.Vertices.Length != VertsPerLandblock)
throw new ArgumentException(
$"Expected {VertsPerLandblock} vertices, got {meshData.Vertices.Length}",
nameof(meshData));
if (meshData.Indices.Length != IndicesPerLandblock)
throw new ArgumentException(
$"Expected {IndicesPerLandblock} indices, got {meshData.Indices.Length}",
nameof(meshData));
if (_idToSlot.ContainsKey(landblockId))
RemoveLandblock(landblockId);
int slot = _alloc.Allocate(out var needsGrow);
if (needsGrow)
{
int newCap = Math.Max(_alloc.Capacity * 2, slot + 1);
EnsureCapacity(newCap);
}
// Bake worldOrigin into vertex positions; capture min/max Z for AABB.
var bakedVerts = new TerrainVertex[VertsPerLandblock];
float zMin = float.MaxValue, zMax = float.MinValue;
for (int i = 0; i < VertsPerLandblock; i++)
{
var v = meshData.Vertices[i];
var worldPos = v.Position + worldOrigin;
bakedVerts[i] = new TerrainVertex(worldPos, v.Normal, v.Data0, v.Data1, v.Data2, v.Data3);
if (worldPos.Z < zMin) zMin = worldPos.Z;
if (worldPos.Z > zMax) zMax = worldPos.Z;
}
if (zMin == float.MaxValue) { zMin = 0f; zMax = 0f; }
// Bake baseVertex into indices on the CPU side (driver-portable pattern).
uint baseVertex = (uint)(slot * VertsPerLandblock);
var bakedIndices = new uint[IndicesPerLandblock];
for (int i = 0; i < IndicesPerLandblock; i++)
bakedIndices[i] = meshData.Indices[i] + baseVertex;
// glBufferSubData into the slot's VBO + EBO regions.
nint vboByteOffset = (nint)(slot * VertsPerLandblock * VertexSize);
nint eboByteOffset = (nint)(slot * IndicesPerLandblock * IndexSize);
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, _globalVbo);
fixed (TerrainVertex* p = bakedVerts)
{
_gl.BufferSubData(BufferTargetARB.ArrayBuffer, vboByteOffset,
(nuint)(VertsPerLandblock * VertexSize), p);
}
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, 0);
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, _globalEbo);
fixed (uint* p = bakedIndices)
{
_gl.BufferSubData(BufferTargetARB.ElementArrayBuffer, eboByteOffset,
(nuint)(IndicesPerLandblock * IndexSize), p);
}
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, 0);
_slots[slot] = new SlotData
{
LandblockId = landblockId,
WorldOrigin = worldOrigin,
FirstIndex = (uint)(slot * IndicesPerLandblock),
IndexCount = IndicesPerLandblock,
AabbMin = new Vector3(worldOrigin.X, worldOrigin.Y, zMin),
AabbMax = new Vector3(worldOrigin.X + LandblockSize, worldOrigin.Y + LandblockSize, zMax),
};
_idToSlot[landblockId] = slot;
}
public void RemoveLandblock(uint landblockId)
{
if (!_idToSlot.TryGetValue(landblockId, out var slot))
return;
_idToSlot.Remove(landblockId);
_slots[slot] = null;
_alloc.Free(slot);
// No GPU clear: the per-frame DEIC array won't reference this slot.
}
public void Draw(
ICamera camera,
FrustumPlanes? frustum = null,
uint? neverCullLandblockId = null,
ReadOnlySpan<Vector4> clipPlanes = default,
Vector4? ndcClipAabb = null)
{
if (_alloc.LoadedCount == 0) return;
Matrix4x4 viewProjection = camera.View * camera.Projection;
// Build visible slot list with per-slot frustum cull.
_visibleSlots.Clear();
for (int slot = 0; slot < _slots.Length; slot++)
{
var data = _slots[slot];
if (data is null) continue;
if (frustum is not null && data.LandblockId != neverCullLandblockId)
{
if (!FrustumCuller.IsAabbVisible(frustum.Value, data.AabbMin, data.AabbMax))
continue;
}
_visibleSlots.Add(slot);
CollectVisibleCells(
_visibleCellIds,
data.LandblockId,
data.WorldOrigin,
data.AabbMin.Z,
data.AabbMax.Z,
frustum,
viewProjection,
clipPlanes,
ndcClipAabb);
}
if (_visibleSlots.Count == 0) return;
// Build DEIC array.
if (_deicScratch.Length < _visibleSlots.Count)
_deicScratch = new DrawElementsIndirectCommand[Math.Max(_visibleSlots.Count, 64)];
for (int i = 0; i < _visibleSlots.Count; i++)
{
var data = _slots[_visibleSlots[i]]!;
_deicScratch[i] = new DrawElementsIndirectCommand
{
Count = (uint)data.IndexCount,
InstanceCount = 1u,
FirstIndex = data.FirstIndex,
BaseVertex = 0, // baked into indices on upload
BaseInstance = 0,
};
}
// Grow indirect buffer if needed.
if (_visibleSlots.Count > _indirectCapacity)
{
_indirectCapacity = Math.Max(64, _visibleSlots.Count * 2);
_gl.BindBuffer(GLEnum.DrawIndirectBuffer, _indirectBuffer);
_gl.BufferData(GLEnum.DrawIndirectBuffer,
(nuint)(_indirectCapacity * sizeof(DrawElementsIndirectCommand)),
null, GLEnum.DynamicDraw);
}
else
{
_gl.BindBuffer(GLEnum.DrawIndirectBuffer, _indirectBuffer);
}
// Upload DEIC array.
fixed (DrawElementsIndirectCommand* p = _deicScratch)
{
_gl.BufferSubData(GLEnum.DrawIndirectBuffer, 0,
(nuint)(_visibleSlots.Count * sizeof(DrawElementsIndirectCommand)), p);
}
// Bind shader + uniforms + atlas handles.
// Verified Phase W Stage 4 (T4.2): terrain projects from the camera view-proj;
// no separate landscape viewpoint to sync. Both uView and uProjection derive
// from the ICamera passed into this method — the same camera used for all other
// renderers in the unified pipeline. Retail's LScape::update_viewpoint
// pre-positions terrain to the outdoor landcell, but acdream uses the
// unified camera matrix everywhere, so no separate viewpoint divergence can occur.
_shader.Use();
UploadTextureTilingOnce();
_shader.SetMatrix4("uView", camera.View);
_shader.SetMatrix4("uProjection", camera.Projection);
var (terrainHandle, alphaHandle) = _atlas.GetBindlessHandles();
// Pass each 64-bit handle as a uvec2 (low 32 bits, high 32 bits).
// GLSL constructs sampler2DArray(uTerrainHandle) at the use site —
// see terrain_modern.frag for why this is the safe pattern.
_gl.ProgramUniform2(_shader.Program, _uTerrainHandleLoc,
(uint)(terrainHandle & 0xFFFFFFFFu), (uint)(terrainHandle >> 32));
_gl.ProgramUniform2(_shader.Program, _uAlphaHandleLoc,
(uint)(alphaHandle & 0xFFFFFFFFu), (uint)(alphaHandle >> 32));
// Phase U.3: bind the terrain clip UBO (binding=2). Shared ClipFrame UBO
// when wired, else the no-clip fallback (count 0 = ungated terrain).
BindClipUboBinding2();
// #108-residual: retail terrain is SINGLE-SIDED — ACRender::landPolysDraw
// (0x006b7040) draws each land triangle ONLY when the camera is on the
// POSITIVE (upper) side of its plane (Plane::which_side2 vs
// Render::FrameCurrent, zFightTerrainAdjust bias). GL backface culling
// evaluates the same per-triangle eye-side predicate at rasterization.
// LandblockMesh emits every triangle CCW in world XY seen from above
// (LandblockMeshTests winding pin), which the unified camera chain
// (CreateLookAt up=+Z + Numerics perspective) maps to CCW window
// winding from above / CW from below (TerrainCullOrientationTests) —
// so FrontFace(Ccw)+Cull(Back) keeps the top side and culls the
// underside. WB drew the whole world with culling DISABLED
// frame-globally (WB GameScene.cs:841 — an editor camera goes
// underground); inheriting that drew terrain DOUBLE-SIDED, and a
// below-grade eye (cellar ascent) saw the UNDERSIDE of the grade
// sheet through the exit-door aperture — the #108 grass window.
// Self-contained state per feedback_render_self_contained_gl_state;
// the frame-global CW + cull-off baseline is restored after the draw.
_gl.Enable(EnableCap.CullFace);
_gl.CullFace(TriangleFace.Back);
_gl.FrontFace(FrontFaceDirection.Ccw);
_gl.BindVertexArray(_globalVao);
_gl.MemoryBarrier(MemoryBarrierMask.CommandBarrierBit);
_gl.MultiDrawElementsIndirect(
PrimitiveType.Triangles, DrawElementsType.UnsignedInt,
(void*)0,
(uint)_visibleSlots.Count,
(uint)sizeof(DrawElementsIndirectCommand));
_gl.BindVertexArray(0);
_gl.BindBuffer(GLEnum.DrawIndirectBuffer, 0);
_gl.FrontFace(FrontFaceDirection.CW);
_gl.Disable(EnableCap.CullFace);
}
public void Dispose()
{
_gl.DeleteVertexArray(_globalVao);
_gl.DeleteBuffer(_globalVbo);
_gl.DeleteBuffer(_globalEbo);
_gl.DeleteBuffer(_indirectBuffer);
if (_fallbackClipUbo != 0) { _gl.DeleteBuffer(_fallbackClipUbo); _fallbackClipUbo = 0; } // Phase U.3
}
// ----------------------------------------------------------------
// Private helpers
// ----------------------------------------------------------------
/// <summary>
/// Upload the texture-array adapter for retail's per-surface repeat count.
/// Retail passes <c>TerrainTex::tex_tiling</c> directly to
/// <c>ImgTex::TileCSI</c> / <c>ImgTex::MergeTexture</c>
/// (`TexMerge::CopyAndTile` 0x00503580, `TexMerge::Merge` 0x005038C0).
/// Uniform values persist for the lifetime of this linked shader program,
/// so the immutable atlas table is uploaded on its first bound draw.
/// </summary>
private void UploadTextureTilingOnce()
{
if (_textureTilingUploaded)
return;
if (_atlas.TilingByLayer.Count != TerrainTextureTilingTable.LayerCapacity)
{
throw new InvalidOperationException(
$"Terrain tiling table has {_atlas.TilingByLayer.Count} entries; " +
$"expected {TerrainTextureTilingTable.LayerCapacity}.");
}
Span<float> values = stackalloc float[TerrainTextureTilingTable.LayerCapacity];
for (int i = 0; i < values.Length; i++)
values[i] = _atlas.TilingByLayer[i];
_gl.Uniform1(_uTexTilingLoc, values);
_textureTilingUploaded = true;
}
/// <summary>
/// Phase U.3: bind the terrain clip UBO to binding=2. Prefers the shared
/// <see cref="ClipFrame"/> UBO (<see cref="SetClipUbo"/>); otherwise lazily
/// creates + binds a no-clip fallback (count 0 = ungated) so the shader never
/// reads an unbound UBO. The fallback is std140-sized to
/// <see cref="ClipFrame.TerrainUboBytes"/> and zero-filled (count 0).
/// </summary>
private void BindClipUboBinding2()
{
if (_sharedClipUbo != 0)
{
_gl.BindBufferBase(BufferTargetARB.UniformBuffer,
ClipFrame.TerrainClipUboBinding, _sharedClipUbo);
return;
}
if (_fallbackClipUbo == 0)
{
_fallbackClipUbo = _gl.GenBuffer();
var zero = stackalloc byte[ClipFrame.TerrainUboBytes];
for (int i = 0; i < ClipFrame.TerrainUboBytes; i++) zero[i] = 0;
_gl.BindBuffer(BufferTargetARB.UniformBuffer, _fallbackClipUbo);
_gl.BufferData(BufferTargetARB.UniformBuffer,
(nuint)ClipFrame.TerrainUboBytes, zero, BufferUsageARB.DynamicDraw);
}
_gl.BindBufferBase(BufferTargetARB.UniformBuffer,
ClipFrame.TerrainClipUboBinding, _fallbackClipUbo);
}
private void AllocateGpuBuffers(int capacitySlots)
{
nuint vboBytes = (nuint)(capacitySlots * VertsPerLandblock * VertexSize);
nuint eboBytes = (nuint)(capacitySlots * IndicesPerLandblock * IndexSize);
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, _globalVbo);
_gl.BufferData(BufferTargetARB.ArrayBuffer, vboBytes, null, BufferUsageARB.DynamicDraw);
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, 0);
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, _globalEbo);
_gl.BufferData(BufferTargetARB.ElementArrayBuffer, eboBytes, null, BufferUsageARB.DynamicDraw);
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, 0);
}
private void ConfigureVao()
{
_gl.BindVertexArray(_globalVao);
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, _globalVbo);
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, _globalEbo);
uint stride = (uint)VertexSize;
// location 0: Position
_gl.EnableVertexAttribArray(0);
_gl.VertexAttribPointer(0, 3, VertexAttribPointerType.Float, false, stride, (void*)0);
// location 1: Normal
_gl.EnableVertexAttribArray(1);
_gl.VertexAttribPointer(1, 3, VertexAttribPointerType.Float, false, stride, (void*)(3 * sizeof(float)));
// locations 2-5: Data0..Data3 (uvec4 byte attributes)
nint dataOffset = 6 * sizeof(float);
_gl.EnableVertexAttribArray(2);
_gl.VertexAttribIPointer(2, 4, VertexAttribIType.UnsignedByte, stride, (void*)dataOffset);
_gl.EnableVertexAttribArray(3);
_gl.VertexAttribIPointer(3, 4, VertexAttribIType.UnsignedByte, stride, (void*)(dataOffset + 4));
_gl.EnableVertexAttribArray(4);
_gl.VertexAttribIPointer(4, 4, VertexAttribIType.UnsignedByte, stride, (void*)(dataOffset + 8));
_gl.EnableVertexAttribArray(5);
_gl.VertexAttribIPointer(5, 4, VertexAttribIType.UnsignedByte, stride, (void*)(dataOffset + 12));
_gl.BindVertexArray(0);
}
internal static void CollectVisibleCells(
HashSet<uint> destination,
uint landblockId,
Vector3 worldOrigin,
float zMin,
float zMax,
FrustumPlanes? frustum,
Matrix4x4 viewProjection,
ReadOnlySpan<Vector4> clipPlanes,
Vector4? ndcClipAabb = null)
{
ArgumentNullException.ThrowIfNull(destination);
const float cellSize = AcDream.Core.Physics.TerrainSurface.CellSize;
const int cellsPerSide = AcDream.Core.Physics.TerrainSurface.CellsPerSide;
uint prefix = landblockId & 0xFFFF0000u;
for (int cellX = 0; cellX < cellsPerSide; cellX++)
{
float minX = worldOrigin.X + cellX * cellSize;
float maxX = minX + cellSize;
for (int cellY = 0; cellY < cellsPerSide; cellY++)
{
float minY = worldOrigin.Y + cellY * cellSize;
float maxY = minY + cellSize;
var cellMin = new Vector3(minX, minY, zMin);
var cellMax = new Vector3(maxX, maxY, zMax);
if (frustum is not null
&& !FrustumCuller.IsAabbVisible(frustum.Value, cellMin, cellMax))
{
continue;
}
// Retail publishes landcell in_view from the clipped landscape
// view, not merely from the camera frustum. The modern renderer
// expresses each doorway slice as homogeneous clip-space planes
// plus its scissor AABB; use both products here so particle
// simulation follows the same visible terrain slice as the GPU.
if (!IsAabbVisibleThroughClipRegion(
cellMin,
cellMax,
viewProjection,
clipPlanes,
ndcClipAabb))
{
continue;
}
uint low = AcDream.Core.Physics.TerrainSurface.ComputeOutdoorCellLowId(
cellX * cellSize,
cellY * cellSize);
destination.Add(prefix | low);
}
}
}
private static bool IsAabbVisibleThroughClipRegion(
Vector3 min,
Vector3 max,
Matrix4x4 viewProjection,
ReadOnlySpan<Vector4> clipPlanes,
Vector4? ndcClipAabb)
{
Vector4 aabb = ndcClipAabb.GetValueOrDefault();
bool hasScissorConstraint = ndcClipAabb.HasValue
&& (aabb.X > -1f || aabb.Y > -1f || aabb.Z < 1f || aabb.W < 1f);
if (clipPlanes.IsEmpty && !hasScissorConstraint)
return true;
Span<Vector4> clipCorners = stackalloc Vector4[8];
for (int corner = 0; corner < clipCorners.Length; corner++)
{
var world = new Vector4(
(corner & 1) == 0 ? min.X : max.X,
(corner & 2) == 0 ? min.Y : max.Y,
(corner & 4) == 0 ? min.Z : max.Z,
1f);
clipCorners[corner] = Vector4.Transform(world, viewProjection);
}
for (int planeIndex = 0; planeIndex < clipPlanes.Length; planeIndex++)
{
if (IsAabbOutsideHomogeneousPlane(clipCorners, clipPlanes[planeIndex]))
{
return false;
}
}
if (!hasScissorConstraint)
return true;
Span<Vector4> scissorPlanes = stackalloc Vector4[4]
{
new( 1f, 0f, 0f, -aabb.X),
new(-1f, 0f, 0f, aabb.Z),
new( 0f, 1f, 0f, -aabb.Y),
new( 0f, -1f, 0f, aabb.W),
};
for (int planeIndex = 0; planeIndex < scissorPlanes.Length; planeIndex++)
{
if (IsAabbOutsideHomogeneousPlane(clipCorners, scissorPlanes[planeIndex]))
{
return false;
}
}
return true;
}
private static bool IsAabbOutsideHomogeneousPlane(
ReadOnlySpan<Vector4> clipCorners,
Vector4 plane)
{
// A linear half-space reaches its maximum over the transformed AABB at
// one of the eight corners. If every corner is negative, no point in
// the cell box can survive this GPU clip plane.
for (int corner = 0; corner < clipCorners.Length; corner++)
{
if (Vector4.Dot(plane, clipCorners[corner]) >= 0f)
return false;
}
return true;
}
private void EnsureCapacity(int newCapacity)
{
if (newCapacity <= _alloc.Capacity) return;
// Allocate new VBO + EBO at new size; copy old contents; swap; recreate VAO.
uint newVbo = _gl.GenBuffer();
uint newEbo = _gl.GenBuffer();
nuint newVboBytes = (nuint)(newCapacity * VertsPerLandblock * VertexSize);
nuint newEboBytes = (nuint)(newCapacity * IndicesPerLandblock * IndexSize);
nuint oldVboBytes = (nuint)(_alloc.Capacity * VertsPerLandblock * VertexSize);
nuint oldEboBytes = (nuint)(_alloc.Capacity * IndicesPerLandblock * IndexSize);
_gl.BindBuffer(BufferTargetARB.ArrayBuffer, newVbo);
_gl.BufferData(BufferTargetARB.ArrayBuffer, newVboBytes, null, BufferUsageARB.DynamicDraw);
_gl.BindBuffer(BufferTargetARB.CopyReadBuffer, _globalVbo);
_gl.BindBuffer(BufferTargetARB.CopyWriteBuffer, newVbo);
_gl.CopyBufferSubData(CopyBufferSubDataTarget.CopyReadBuffer, CopyBufferSubDataTarget.CopyWriteBuffer,
0, 0, oldVboBytes);
_gl.DeleteBuffer(_globalVbo);
_globalVbo = newVbo;
_gl.BindBuffer(BufferTargetARB.ElementArrayBuffer, newEbo);
_gl.BufferData(BufferTargetARB.ElementArrayBuffer, newEboBytes, null, BufferUsageARB.DynamicDraw);
_gl.BindBuffer(BufferTargetARB.CopyReadBuffer, _globalEbo);
_gl.BindBuffer(BufferTargetARB.CopyWriteBuffer, newEbo);
_gl.CopyBufferSubData(CopyBufferSubDataTarget.CopyReadBuffer, CopyBufferSubDataTarget.CopyWriteBuffer,
0, 0, oldEboBytes);
_gl.DeleteBuffer(_globalEbo);
_globalEbo = newEbo;
// Recreate VAO with new buffer bindings.
_gl.DeleteVertexArray(_globalVao);
_globalVao = _gl.GenVertexArray();
ConfigureVao();
// Grow slot tracking array.
Array.Resize(ref _slots, newCapacity);
_alloc.GrowTo(newCapacity);
}
private sealed class SlotData
{
public uint LandblockId;
public Vector3 WorldOrigin;
public uint FirstIndex;
public int IndexCount;
public Vector3 AabbMin;
public Vector3 AabbMax;
}
}