skycraft: now with landing!

Once landed, position is locked to the body it landed on.
Not enough fuel to launch again.

skycraft/chunk.ts

@@ -4,7 +4,7 @@ import {memoize} from 'wmc-common/memoize';
 
 type direction = ('-x' | '+x' | '-y' | '+y' | '-z' | '+z');
 
-const BlockType = {
+export const BlockType = {
     UNDEFINED: 0,
     AIR: 1,
     DIRT: 2,
@@ -18,7 +18,6 @@ const BlockType = {
 
 const CHUNKSIZE = 32;
 
-
 /** seed: some kind of number uniquely defining the body
  *  x, y, z: space coordinates in the body's frame
  *
@@ -304,10 +303,115 @@ function getBodyChunks(seed: number) {
     return chunks;
 }
 
+/** fake chunk map re-using the memoize */
+class ChunkMap {
+    constructor(seed) {
+        this.seed = seed;
+    }
+
+    get(i, j, k) {
+        return getChunk(this.seed, i, j, k);
+    }
+
+    has(i, j, k) {
+        return getChunk(this.seed, i, j, k) !== undefined;
+    }
+}
+
 export function getBodyGeometry(seed: number) {
     const faces = getBodyChunks(seed)
         .filter(chunk => !chunk.underground)
         .map(chunk => [...makeChunkFaces(chunk)]);
 
-    return faces.reduce((a, b) => a.concat(b));
+    return {
+        faces: faces.reduce((a, b) => a.concat(b)),
+        chunkMap: new ChunkMap(seed),
+    };
+}
+
+function blockLookup(chunkMap, x, y, z) {
+    const chunki = Math.floor((x + CHUNKSIZE / 2) / CHUNKSIZE);
+    const chunkj = Math.floor((y + CHUNKSIZE / 2) / CHUNKSIZE);
+    const chunkk = Math.floor((z + CHUNKSIZE / 2) / CHUNKSIZE);
+
+    const chunk = chunkMap.get(chunki, chunkj, chunkk);
+    if (chunk === undefined) {
+        return {
+            type: BlockType.UNDEFINED,
+        };
+    }
+
+    const i = Math.floor(x - chunk.position[0] + 0.5);
+    const j = Math.floor(y - chunk.position[1] + 0.5);
+    const k = Math.floor(z - chunk.position[2] + 0.5);
+
+    const blockIndex = CHUNKSIZE * (CHUNKSIZE * i + j) + k;
+
+    return {
+        type: chunk.blocks[blockIndex],
+        centerPosition: [
+            chunk.position[0] + i,
+            chunk.position[1] + j,
+            chunk.position[2] + k,
+        ],
+        chunk,
+        blockIndex,
+    };
+}
+
+function movePoint(p, s, u) {
+    return linalg.add(p, linalg.scale(u, s));
+}
+
+function minIndex(arr) {
+    return arr.reduce((min, val, i) => val >= arr[min] ? min : i, -1);
+}
+
+/** Imported from wmc, looks like it calculates the distance to the next grid block */
+function rayThroughGrid(origin, direction, maxDistance) {
+    const range = i => [...Array(i).keys()];
+
+    const nextGrid = range(3).map(i => direction[i] > 0 ?
+        Math.floor(origin[i] + 0.5) + 0.5 :
+        Math.floor(origin[i] + 0.5) - 0.5);
+    const distanceToGrid = range(3).map(i => (nextGrid[i] - origin[i]) / direction[i])
+        .map(v => v === 0.0 ? Number.POSITIVE_INFINITY : v);
+    const axis = minIndex(distanceToGrid);
+    const rayLength = distanceToGrid[axis];
+
+    if (rayLength > maxDistance) {
+        return {};
+    }
+
+    const position = movePoint(origin, distanceToGrid[axis], direction);
+    const normal = range(3).map(i => i === axis ? -Math.sign(direction[i]) : 0);
+
+    return {position, normal, distance: rayLength};
+}
+
+/** needs a blockLookup function, finds the first non-air block along a ray */
+export function castRay(chunkMap, origin, direction, maxDistance=CHUNKSIZE) {
+    let currentPoint = origin;
+
+    while (maxDistance > 0) {
+        const {position, normal, distance} = rayThroughGrid(currentPoint, direction, maxDistance);
+
+        if (position === undefined) {
+            return;
+        }
+
+        maxDistance -= distance;
+        currentPoint = movePoint(position, 0.01, direction);
+        const blockCenter = movePoint(position, -0.5, normal);
+        const block = blockLookup(chunkMap, ...blockCenter);
+
+        if (block.type === BlockType.AIR) {
+            continue;
+        }
+
+        return {
+            block,
+            normal,
+        };
+    }
 }

skycraft/draw.ts

@@ -250,7 +250,7 @@ function getObjects(context, body, parentPosition = undefined) {
     const {position, orientation, glowColor, specularColor} = body;
 
     if (body.glBuffer === undefined) {
-        body.glBuffer = makeBufferFromFaces(gl, body.geometry);
+        body.glBuffer = makeBufferFromFaces(gl, body.geometry.faces);
     }
 
     objects.push({
@@ -263,14 +263,21 @@ function getObjects(context, body, parentPosition = undefined) {
     });
     if (parentPosition !== undefined) {
         const orbitObject = makeOrbitObject(gl, context.orbitGlContext, body.orbit, parentPosition);
-        objects.push(orbitObject);
+        //objects.push(orbitObject);
     } else {
+        const tfs = [player.tf];
+        if (context.landed) {
+            const body = context.landedBody;
+            const bodyTf = se3.product(se3.translation(...body.position), body.orientation);
+            tfs.splice(0, 0, bodyTf);
+        }
+        const tf = tfs.reduce(se3.product);
         const shipOrientation = [
-            se3.rotationOnly(player.tf),
+            se3.rotationOnly(tf),
             //se3.rotationOnly(context.camera.tf),
             se3.rotxyz(-Math.PI / 2, Math.PI / 2, Math.PI / 2),
         ].reduce(se3.product);
-        const shipPos = player.position;
+        const shipPos = se3.apply(tf, [0, 0, 0, 1]);
         objects.push({
             geometry: makeBufferFromFaces(gl, context.spaceship),
             orientation: shipOrientation,
@@ -297,7 +304,7 @@ export function draw(context) {
     const {gl, camera, player, universe, orbit, orbitGlContext, orbitBody} = context;
     const {skyColor, ambiantLight, projMatrix} = context;
     const objects = getObjects(context, universe); 
-    if (orbit !== undefined && orbit.excentricity < 1) {
+    if (orbit !== undefined && orbit.excentricity < 1 && !context.landing) {
         objects.push(makeOrbitObject(gl, orbitGlContext, orbit, orbitBody.position));
     }
 
@@ -313,11 +320,18 @@ export function draw(context) {
 
     gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
 
-    const viewMatrix = se3.inverse([
+    const playerView = [
         player.tf,  // player position & orientation
         camera.tf,  // camera orientation relative to player
         se3.translation(0, 1, 4),  // step back from the player
-    ].reduce(se3.product));
+    ];
+    if (context.landed) {
+        const body = context.landedBody;
+        const bodyTf = se3.product(se3.translation(...body.position), body.orientation);
+        playerView.splice(0, 0, bodyTf);
+    }
+
+    const viewMatrix = se3.inverse(playerView.reduce(se3.product));
     let lastGlContext;
 
     for (const {position, orientation, geometry, glContext, glowColor, specularColor} of objects) {

skycraft/index.ts

@@ -3,8 +3,8 @@ import { makeFace } from 'wmc-common/geometry';
 import * as linalg from './linalg';
 import { loadObjModel } from './obj';
 import * as se3 from 'wmc-common/se3';
-import { computeOrbit, findSoi, getCartesianState, updateBodyPhysics } from './orbit';
+import { computeOrbit, findSoi, getCartesianState, updateBodyPhysics, isInSoi } from './orbit';
-import { getBodyGeometry } from './chunk';
+import { getBodyGeometry, castRay, BlockType } from './chunk';
 import { draw, getOrbitDrawContext, initWorldGl } from './draw';
 import * as quat from './quat';
 
@@ -157,18 +157,10 @@ function initUiListeners(canvas: HTMLCanvasElement, context) {
                         delete context.orbit;
                         return false;
                     case 'KeyL':
-                        if (closeToPlanet(context)) {
+                        context.landing = !context.landing;
-                            context.landing = True;
-                        }
                         return false;
                     case 'Space':
-                        if (!context.flying) {
+                        context.pause = !context.pause;
-                            if (context.jumpAmount > 0) {
-                                const amount = context.jumpForce;
-                                context.player.velocity[1] = amount;
-                                context.jumpAmount -= 1;
-                            }
-                        }
                         return false;
                 }
             } else {
@@ -236,6 +228,16 @@ function handleInput(context) {
         }
     };
 
+    const roll = (amount: number) => {
+        if (context.keys.has('ShiftLeft')) {
+            amount *= 10;
+        }
+        context.camera.tf =[
+            context.camera.tf,
+            se3.rotz(amount),
+        ].reduce(se3.product);
+    };
+
     context.keys.forEach(key => {
         switch (key) {
             case 'KeyW':
@@ -250,6 +252,12 @@ function handleInput(context) {
             case 'KeyD':
                 move(0.0, 0.5);
                 return;
+            case 'KeyQ':
+                roll(0.02);
+                return;
+            case 'KeyE':
+                roll(-0.02);
+                return;
             case 'KeyR':
                 context.timeOffset += 1;
                 return;
@@ -259,15 +267,120 @@ function handleInput(context) {
 
 function slerp(current: linalg.Mat4, target: linalg.Mat4, maxVelocity: number) : linalg.Mat4 {
     const q0 = quat.mat2Quat(current);
-    const q1 = quat.mat2Quat(target);
+    let q1 = quat.mat2Quat(target);
 
     const dq = quat.diff(q1, q0);
     const maxt = maxVelocity / quat.norm(dq);
 
-    const q = quat.normalize(quat.add(q0, quat.scale(dq, Math.min(1, maxt))));
+    //const q = quat.normalize(quat.add(q0, quat.scale(dq, Math.min(1, maxt))));
+    const t = maxVelocity;
+    if (quat.dot(q0, q1) < 0) {
+        q1 = quat.scale(q1, -1);
+    }
+    const q = quat.normalize(quat.add(quat.scale(q0, 1 - t), quat.scale(q1, t)));
     return quat.quat2Mat(q);
 }
 
+function distanceToGround(body: Body, position: number[], direction: number[]) : number {
+    const inChunkOrientation = se3.inverse(body.orientation);
+    const toChunk = vec => se3.apply(inChunkOrientation, vec.concat([0]));
+    const directionInChunk = toChunk(direction);
+    const positionInChunk = toChunk(linalg.diff(position, body.position));
+
+    const hit = castRay(body.geometry.chunkMap, positionInChunk, directionInChunk);
+
+    if (hit === undefined || hit.block.type === BlockType.UNDEFINED || hit.block.type === undefined) {
+        const ray = linalg.diff(position, body.position);
+        return {
+            distance: linalg.norm(ray),
+            normal: linalg.normalize(ray),
+        };
+    }
+    
+    const distance = linalg.norm(linalg.diff(positionInChunk, hit.block.centerPosition));
+    const normal = se3.apply(body.orientation, hit.normal.concat([0]));
+    return {distance, normal};
+}
+
+function autoLand(context) {
+    const p = context.player;
+    // 0. check prereqs:
+    //   - none
+    // 1. adjust tangential speed to match body rotational
+    // 2. cast ray towards center
+    // 3. while high, go towards center
+    // 4. when low, go towards ground
+    // 5. stop when on ground
+    const kShipRotateSpeed = 0.1;
+
+    const body = findSoi(context.universe, p.position);
+    const toBodyCenter = linalg.diff(body.position, p.position);
+    const {distance: altitude, normal: surfaceNormal} = distanceToGround(body, p.position, linalg.normalize(toBodyCenter));
+
+    // figure out tangential speed
+    const spinSpeed = linalg.add(body.velocity, linalg.cross(body.spin, linalg.scale(toBodyCenter, -1)));
+    const dv = linalg.diff(spinSpeed, p.velocity);
+    // remove vertical component
+    const vertical = linalg.scale(surfaceNormal, -linalg.dot(dv, surfaceNormal));
+    const smallDv = linalg.scale(linalg.add(dv, vertical), 0.01);
+//    const smallDv = linalg.scale(dv, 0.05);
+    p.velocity = linalg.add(p.velocity, smallDv);
+
+    // up is up
+    const shipZ = se3.apply(p.tf, [0, 0, 1, 0]);
+    const ny = surfaceNormal;
+    const nx = linalg.normalize(linalg.cross(ny, shipZ));
+    const nz = linalg.normalize(linalg.cross(nx, ny));
+
+    const targetOrientation = se3.fromBases(nx, ny, nz);
+    const currentOrientation = slerp(p.tf, targetOrientation, kShipRotateSpeed);
+    p.tf = se3.setOrientation(p.tf, currentOrientation);
+
+    if (altitude < 1.5) {
+        const upward = linalg.dot(linalg.diff(p.velocity, body.velocity), surfaceNormal);
+        if (upward < -2) {
+            p.velocity = linalg.add(p.velocity, linalg.scale(surfaceNormal, -2*upward));
+            context.landing = false;
+        } else if (upward < 0) {
+            context.landed = true;
+            context.landedBody = body;
+
+            p.tf = [
+                se3.inverse(body.orientation),
+                se3.inverse(se3.translation(...body.position)),
+                p.tf,
+            ].reduce(se3.product);
+            p.velocity = [0, 0, 0];
+            p.position = se3.apply(p.tf, [0, 0, 0, 1]);
+        }
+    }
+//    p.velocity = linalg.add(p.velocity, linalg.scale(surfaceNormal, dvup));
+}
+
+function effectiveGravity(position: number[], rootBody: Body) : number[] {
+    let body = rootBody;
+    let acceleration = [0, 0, 0];
+    while (body !== undefined) {
+        const toBodyCenter = linalg.diff(body.position, position);
+        const d = linalg.norm(toBodyCenter);
+        const gravity = body.mass / d**3;
+        acceleration = linalg.add(acceleration, linalg.scale(toBodyCenter, gravity));
+
+        const parentMass = body.mass;
+        const children = body.children || [];
+        body = undefined;
+        for (const child of children) {
+            if (!isInSoi(child, parentMass, position)) {
+                continue;
+            }
+            body = child;
+            break;
+        }
+    }
+
+    return acceleration;
+}
+
 function updatePhysics(time: number, context) {
     const {player} = context;
     const dt = time - (context.lastTime || 0);
@@ -275,37 +388,41 @@ function updatePhysics(time: number, context) {
 
     player.position = se3.apply(player.tf, [0, 0, 0, 1]);
 
+    if (!context.pause) {
         updateBodyPhysics(time, context.universe);
+    }
 
-    const dr = slerp(se3.identity(), context.camera.tf, 0.007);
+    const kShipRotateSpeed = 0.1;
+
+    if (context.landed) {
+        return; // TODO: implement
+    }
+
+    if (context.landing) {
+        autoLand(context);
+    } else {
+        // allow acdjusting camera
+        const dr = slerp(se3.identity(), context.camera.tf, kShipRotateSpeed);
         player.tf = se3.product(player.tf, dr);
         context.camera.tf = se3.product(context.camera.tf, se3.inverse(dr));
+    }
+
+    if (context.flying) {
+        // no physics, just magically moving around
+        return;
+    }
+
+    const gravity = effectiveGravity(player.position, context.universe);
+    player.velocity = linalg.add(player.velocity, linalg.scale(gravity, dt));
 
-    if (!context.flying) {
-        if (context.orbit === undefined) {
     const newPos = linalg.add(player.position, linalg.scale(player.velocity, dt));
-            const dx = linalg.diff(newPos, player.position);
+    player.tf = se3.setPosition(player.tf, newPos);
-            player.tf = se3.product(se3.translation(...dx), player.tf);
 
+    if (context.orbit === undefined) {
         const body = findSoi(context.universe, context.player.position);
         context.orbit = computeOrbit(player, body, time);
         console.log(`orbiting ${body.name}, excentricity: ${context.orbit.excentricity}`);
         context.orbitBody = body;
-        } else {
-            const {position: orbitPos, velocity: orbitVel} = getCartesianState(
-                context.orbit, context.orbitBody.mass, time);
-            if (orbitPos === undefined) {
-                const newPos = linalg.add(player.position, linalg.scale(player.velocity, dt));
-                const dx = linalg.diff(newPos, player.position);
-                player.tf = se3.product(se3.translation(...dx), player.tf);
-            } else {
-                const position = linalg.add(orbitPos, context.orbitBody.position);
-                const velocity = linalg.add(orbitVel, context.orbitBody.velocity);
-                player.velocity = velocity;
-                const dx = linalg.diff(position, player.position);
-                player.tf = se3.product(se3.translation(...dx), player.tf);
-            }
-        }
     }
 }
 
@@ -336,14 +453,16 @@ function tick(time: number, context) {
 }
 
 function makeCube(texture) {
-    return [
+    return {
+        faces: [
             makeFace('-x', texture, [-0.5, 0, 0]),
             makeFace('+x', texture, [+0.5, 0, 0]),
             makeFace('-y', texture, [0, -0.5, 0]),
             makeFace('+y', texture, [0, +0.5, 0]),
             makeFace('-z', texture, [0, 0, -0.5]),
             makeFace('+z', texture, [0, 0, +0.5]),
-    ];
+        ]
+    };
 }
 
 async function main() {
@@ -399,7 +518,6 @@ async function main() {
     initUiListeners(canvas, context);
 
     const starshipGeom = await modelPromise;
-    console.log(`loaded ${starshipGeom.length} triangles`);
 
     context.spaceship = starshipGeom;
 

skycraft/orbit.ts

@@ -52,6 +52,14 @@ export function updateBodyPhysics(time: number, body: Body, parentBody : Body |
     }
 }
 
+export function isInSoi(body: Body, parentMass: number, position: number[]) : boolean {
+    const soi = body.orbit.semimajorAxis * Math.pow(body.mass / parentMass, 2/5);
+    const pos = position;
+    const bod = body.position;
+    const dr = [pos[0] - bod[0], pos[1] - bod[1], pos[2] - bod[2]];
+    return (dr[0]**2 + dr[1]**2 + dr[2]**2 < soi**2);
+}
+
 export function findSoi(rootBody: Body, position: number[]) : Body {
     const bodies = [rootBody];
     let body : Body;
@@ -63,11 +71,7 @@ export function findSoi(rootBody: Body, position: number[]) : Body {
         }
 
         for (const child of body.children) {
-            const soi = child.orbit.semimajorAxis * Math.pow(child.mass / body.mass, 2/5);
+            if (isInSoi(child, body.mass, position)) {
-            const pos = position;
-            const bod = child.position;
-            const dr = [pos[0] - bod[0], pos[1] - bod[1], pos[2] - bod[2]];
-            if (dr[0]**2 + dr[1]**2 + dr[2]**2 < soi**2) {
                 bodies.push(child);
             }
         }