Add terrain brush core and geometry implementations
This commit is contained in:
91
src/core/terrain-brush.ts
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91
src/core/terrain-brush.ts
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import type { Terrain } from "../document/terrains";
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export type TerrainBrushTool = "raise" | "lower" | "smooth" | "flatten";
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export interface TerrainBrushSettings {
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radius: number;
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strength: number;
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falloff: number;
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}
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export interface ArmedTerrainBrushState extends TerrainBrushSettings {
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terrainId: string;
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tool: TerrainBrushTool;
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}
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export interface TerrainBrushStrokeCommit {
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terrain: Terrain;
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commandLabel: string;
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tool: TerrainBrushTool;
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}
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export const DEFAULT_TERRAIN_BRUSH_RADIUS = 2;
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export const DEFAULT_TERRAIN_BRUSH_STRENGTH = 0.35;
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export const DEFAULT_TERRAIN_BRUSH_FALLOFF = 0.6;
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export const MIN_TERRAIN_BRUSH_RADIUS = 0.25;
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export const MAX_TERRAIN_BRUSH_RADIUS = 12;
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export const MIN_TERRAIN_BRUSH_STRENGTH = 0.05;
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export const MAX_TERRAIN_BRUSH_STRENGTH = 1;
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export const MIN_TERRAIN_BRUSH_FALLOFF = 0;
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export const MAX_TERRAIN_BRUSH_FALLOFF = 1;
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function clamp(value: number, min: number, max: number): number {
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return Math.min(max, Math.max(min, value));
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}
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export function clampTerrainBrushRadius(radius: number): number {
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if (!Number.isFinite(radius)) {
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return DEFAULT_TERRAIN_BRUSH_RADIUS;
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}
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return clamp(radius, MIN_TERRAIN_BRUSH_RADIUS, MAX_TERRAIN_BRUSH_RADIUS);
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}
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export function clampTerrainBrushStrength(strength: number): number {
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if (!Number.isFinite(strength)) {
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return DEFAULT_TERRAIN_BRUSH_STRENGTH;
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}
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return clamp(
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strength,
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MIN_TERRAIN_BRUSH_STRENGTH,
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MAX_TERRAIN_BRUSH_STRENGTH
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);
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}
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export function clampTerrainBrushFalloff(falloff: number): number {
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if (!Number.isFinite(falloff)) {
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return DEFAULT_TERRAIN_BRUSH_FALLOFF;
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}
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return clamp(
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falloff,
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MIN_TERRAIN_BRUSH_FALLOFF,
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MAX_TERRAIN_BRUSH_FALLOFF
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);
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}
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export function createDefaultTerrainBrushSettings(): TerrainBrushSettings {
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return {
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radius: DEFAULT_TERRAIN_BRUSH_RADIUS,
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strength: DEFAULT_TERRAIN_BRUSH_STRENGTH,
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falloff: DEFAULT_TERRAIN_BRUSH_FALLOFF
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};
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}
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export function getTerrainBrushToolLabel(tool: TerrainBrushTool): string {
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switch (tool) {
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case "raise":
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return "Raise";
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case "lower":
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return "Lower";
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case "smooth":
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return "Smooth";
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case "flatten":
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return "Flatten";
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}
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}
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export function getTerrainBrushCommandLabel(tool: TerrainBrushTool): string {
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return `${getTerrainBrushToolLabel(tool)} terrain`;
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}
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253
src/geometry/terrain-brush.ts
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253
src/geometry/terrain-brush.ts
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@@ -0,0 +1,253 @@
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import type { Vec3 } from "../core/vector";
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import type {
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TerrainBrushSettings,
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TerrainBrushTool
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} from "../core/terrain-brush";
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import {
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createTerrain,
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getTerrainHeightAtSample,
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getTerrainSampleIndex,
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type Terrain
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} from "../document/terrains";
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export interface TerrainBrushPoint {
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x: number;
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z: number;
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}
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function clamp(value: number, min: number, max: number): number {
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return Math.min(max, Math.max(min, value));
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}
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function lerp(start: number, end: number, t: number): number {
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return start + (end - start) * t;
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}
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function clamp01(value: number): number {
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return clamp(value, 0, 1);
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}
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export function getTerrainBrushWeight(
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distance: number,
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radius: number,
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falloff: number
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): number {
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if (!Number.isFinite(radius) || radius <= 0) {
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return 0;
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}
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if (distance >= radius) {
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return 0;
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}
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const normalizedDistance = clamp01(distance / radius);
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const baseWeight = 1 - normalizedDistance;
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const exponent = 1 + clamp01(falloff) * 3;
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return Math.pow(baseWeight, exponent);
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}
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export function sampleTerrainHeightAtWorldPosition(
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terrain: Terrain,
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worldX: number,
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worldZ: number,
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clampToBounds = false
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): number | null {
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const sampleSpaceX = (worldX - terrain.position.x) / terrain.cellSize;
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const sampleSpaceZ = (worldZ - terrain.position.z) / terrain.cellSize;
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const maxSampleX = terrain.sampleCountX - 1;
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const maxSampleZ = terrain.sampleCountZ - 1;
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if (!clampToBounds) {
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if (
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sampleSpaceX < 0 ||
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sampleSpaceX > maxSampleX ||
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sampleSpaceZ < 0 ||
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sampleSpaceZ > maxSampleZ
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) {
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return null;
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}
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}
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const clampedSampleX = clamp(sampleSpaceX, 0, maxSampleX);
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const clampedSampleZ = clamp(sampleSpaceZ, 0, maxSampleZ);
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const x0 = Math.floor(clampedSampleX);
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const z0 = Math.floor(clampedSampleZ);
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const x1 = Math.min(maxSampleX, x0 + 1);
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const z1 = Math.min(maxSampleZ, z0 + 1);
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const tx = clampedSampleX - x0;
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const tz = clampedSampleZ - z0;
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const top = lerp(
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getTerrainHeightAtSample(terrain, x0, z0),
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getTerrainHeightAtSample(terrain, x1, z0),
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tx
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);
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const bottom = lerp(
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getTerrainHeightAtSample(terrain, x0, z1),
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getTerrainHeightAtSample(terrain, x1, z1),
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tx
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);
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return lerp(top, bottom, tz);
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}
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export function createTerrainBrushPreviewPoints(
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terrain: Terrain,
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center: TerrainBrushPoint,
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radius: number,
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segmentCount = 36,
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heightOffset = 0.06
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): Vec3[] {
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const points: Vec3[] = [];
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const minX = terrain.position.x;
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const minZ = terrain.position.z;
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const maxX =
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terrain.position.x + (terrain.sampleCountX - 1) * terrain.cellSize;
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const maxZ =
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terrain.position.z + (terrain.sampleCountZ - 1) * terrain.cellSize;
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for (let segmentIndex = 0; segmentIndex <= segmentCount; segmentIndex += 1) {
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const angle = (segmentIndex / segmentCount) * Math.PI * 2;
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const unclampedX = center.x + Math.cos(angle) * radius;
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const unclampedZ = center.z + Math.sin(angle) * radius;
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const worldX = clamp(unclampedX, minX, maxX);
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const worldZ = clamp(unclampedZ, minZ, maxZ);
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const height =
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sampleTerrainHeightAtWorldPosition(terrain, worldX, worldZ, true) ?? 0;
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points.push({
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x: worldX,
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y: terrain.position.y + height + heightOffset,
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z: worldZ
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});
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}
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return points;
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}
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function getTerrainSmoothTargetHeight(
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terrain: Terrain,
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sourceHeights: readonly number[],
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sampleX: number,
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sampleZ: number
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): number {
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let total = 0;
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let count = 0;
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for (
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let neighborZ = Math.max(0, sampleZ - 1);
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neighborZ <= Math.min(terrain.sampleCountZ - 1, sampleZ + 1);
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neighborZ += 1
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) {
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for (
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let neighborX = Math.max(0, sampleX - 1);
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neighborX <= Math.min(terrain.sampleCountX - 1, sampleX + 1);
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neighborX += 1
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) {
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total +=
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sourceHeights[getTerrainSampleIndex(terrain, neighborX, neighborZ)] ?? 0;
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count += 1;
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}
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}
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return count === 0
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? sourceHeights[getTerrainSampleIndex(terrain, sampleX, sampleZ)] ?? 0
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: total / count;
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}
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export function applyTerrainBrushStamp(options: {
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terrain: Terrain;
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center: TerrainBrushPoint;
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settings: TerrainBrushSettings;
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tool: TerrainBrushTool;
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referenceHeight?: number | null;
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}): Terrain {
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const { terrain, center, settings, tool, referenceHeight = null } = options;
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const { radius, strength, falloff } = settings;
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const minSampleX = Math.max(
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0,
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Math.floor((center.x - terrain.position.x - radius) / terrain.cellSize)
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);
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const maxSampleX = Math.min(
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terrain.sampleCountX - 1,
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Math.ceil((center.x - terrain.position.x + radius) / terrain.cellSize)
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);
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const minSampleZ = Math.max(
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0,
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Math.floor((center.z - terrain.position.z - radius) / terrain.cellSize)
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);
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const maxSampleZ = Math.min(
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terrain.sampleCountZ - 1,
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Math.ceil((center.z - terrain.position.z + radius) / terrain.cellSize)
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);
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const sourceHeights = terrain.heights;
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const nextHeights = [...sourceHeights];
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const smoothingStrength = clamp01(strength);
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let changed = false;
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for (let sampleZ = minSampleZ; sampleZ <= maxSampleZ; sampleZ += 1) {
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for (let sampleX = minSampleX; sampleX <= maxSampleX; sampleX += 1) {
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const worldX = terrain.position.x + sampleX * terrain.cellSize;
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const worldZ = terrain.position.z + sampleZ * terrain.cellSize;
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const distance = Math.hypot(worldX - center.x, worldZ - center.z);
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const weight = getTerrainBrushWeight(distance, radius, falloff);
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if (weight <= 0) {
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continue;
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}
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const sampleIndex = getTerrainSampleIndex(terrain, sampleX, sampleZ);
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const currentHeight = sourceHeights[sampleIndex] ?? 0;
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let nextHeight = currentHeight;
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switch (tool) {
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case "raise":
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nextHeight = currentHeight + strength * weight;
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break;
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case "lower":
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nextHeight = currentHeight - strength * weight;
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break;
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case "smooth": {
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const smoothTargetHeight = getTerrainSmoothTargetHeight(
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terrain,
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sourceHeights,
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sampleX,
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sampleZ
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);
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nextHeight = lerp(
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currentHeight,
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smoothTargetHeight,
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clamp01(smoothingStrength * weight)
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);
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break;
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}
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case "flatten":
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if (referenceHeight === null || !Number.isFinite(referenceHeight)) {
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throw new Error(
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"Flatten terrain brush stamps require a finite reference height."
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);
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}
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nextHeight = lerp(
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currentHeight,
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referenceHeight,
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clamp01(smoothingStrength * weight)
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);
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break;
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}
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if (nextHeight !== currentHeight) {
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nextHeights[sampleIndex] = nextHeight;
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changed = true;
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}
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}
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}
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return changed ? createTerrain({ ...terrain, heights: nextHeights }) : terrain;
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}
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export function getTerrainBrushStrokeSpacing(
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terrain: Terrain,
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settings: TerrainBrushSettings
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): number {
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return Math.max(terrain.cellSize * 0.5, settings.radius * 0.25);
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}
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