1st working swept

engine/Rect.ts

@@ -38,10 +38,10 @@ export function strokeRect(
 	ctx.globalAlpha = alpha;
 	ctx.lineWidth = lineWidth;
 	ctx.strokeRect(
-		rect.position.x - 0.5,
-		rect.position.y - 0.5,
-		rect.width,
-		rect.height,
+		rect.position.x + 0.5,
+		rect.position.y + 0.5,
+		rect.width - 1,
+		rect.height - 1,
 	);
 	ctx.restore();
 }
@@ -53,13 +53,8 @@ export function fillRect(
 	alpha: number = 1.0,
 ): void {
 	ctx.save();
-	ctx.strokeStyle = color;
+	ctx.fillStyle = color;
 	ctx.globalAlpha = alpha;
-	ctx.fillRect(
-		rect.position.x - 0.5,
-		rect.position.y - 0.5,
-		rect.width,
-		rect.height,
-	);
+	ctx.fillRect(rect.position.x, rect.position.y, rect.width, rect.height);
 	ctx.restore();
 }

engine/system/physics.ts

@@ -1,8 +1,9 @@
 import type { Circle } from "#/engine/Circle.ts";
 import type { Polygon } from "#/engine/Polygon.ts";
-import { createRect, type Rect } from "#/engine/Rect.ts";
+import { createRect, fillRect, type Rect, strokeRect } from "#/engine/Rect.ts";
 import $ from "#/engine/Scene.ts";
 import { createVector, type Vector } from "#/engine/Vector.ts";
+import { viewport } from "#/engine/Viewport.ts";
 
 export enum Shape {
 	Cirle,
@@ -22,7 +23,13 @@ type CollisionBuffer = {
 	slice: Array<Collision>;
 };
 
-type Collide = (collision: Collision, cid: string) => void;
+type Collide = (
+	collision: Collision,
+	cid: string,
+	self: Collider,
+	velocity: Vector,
+	other: Collider,
+) => void;
 
 export type Collider = {
 	shape: Shape;
@@ -73,25 +80,77 @@ export function createCollider(
 	};
 }
 
-const infAABB = createRect(createVector(), 0, 0);
-function sweptAABB(self: Collider, other: Collider, velocity: Vector): void {
-	infAABB.position.x = other.aabb.position.x - self.aabb.width / 2;
-	infAABB.position.y = other.aabb.position.y - self.aabb.height / 2;
-	infAABB.width = other.aabb.width - self.aabb.width;
-	infAABB.height = other.aabb.height - self.aabb.height;
+const inflAABB = createRect(createVector(), 0, 0);
+function sweptAABB(
+	self: Collider,
+	velocity: Vector,
+	other: Collider,
+): null | number {
+	inflAABB.position.x = other.aabb.position.x - self.aabb.width;
+	inflAABB.position.y = other.aabb.position.y - self.aabb.height;
+	inflAABB.width = other.aabb.width + self.aabb.width;
+	inflAABB.height = other.aabb.height + self.aabb.height;
 
-	//
+	let txNear = (inflAABB.position.x - self.aabb.position.x) / velocity.x;
+	let txFar =
+		(inflAABB.position.x + inflAABB.width - self.aabb.position.x) / velocity.x;
+
+	let tyNear = (inflAABB.position.y - self.aabb.position.y) / velocity.y;
+	let tyFar =
+		(inflAABB.position.y + inflAABB.height - self.aabb.position.y) / velocity.y;
+
+	if (txNear > txFar) {
+		[txNear, txFar] = [txFar, txNear];
+	}
+	if (tyNear > tyFar) {
+		[tyNear, tyFar] = [tyFar, tyNear];
 	}
 
-function collideWithCirle(collision: Collision, cid: string) {
+	// no collision at all
+	if (txNear > tyFar || tyNear > txFar) {
+		return null;
+	}
+
+	const thNear = Math.max(txNear, tyNear);
+	const thFar = Math.min(txFar, tyFar);
+
+	// thMax < 0, collision is behind a frame
+	// thMin > 1, collision is ahead a frame
+	if (thFar < 0 || thNear > 1) {
+		return null;
+	}
+
+	return thNear;
+}
+
+function collideWithCirle(
+	collision: Collision,
+	cid: string,
+	self: Collider,
+	velocity: Vector,
+	other: Collider,
+) {
 	collision.cid = cid;
 }
 
-function collideWithRect(collision: Collision, cid: string) {
-	collision.cid = cid;
+function collideWithRect(
+	collision: Collision,
+	cid: string,
+	self: Collider,
+	velocity: Vector,
+	other: Collider,
+) {
+	const th = sweptAABB(self, velocity, other);
+	collision.cid = th !== null ? cid : "";
 }
 
-function collideWithPolygon(collision: Collision, cid: string) {
+function collideWithPolygon(
+	collision: Collision,
+	cid: string,
+	self: Collider,
+	velocity: Vector,
+	other: Collider,
+) {
 	collision.cid = cid;
 }
 
@@ -172,15 +231,15 @@ export function moveAndCollide(
 		const collision = next(self.buffer);
 		switch (self.shape) {
 			case CIRCLE: {
-				circleCollide[other.shape](collision, cid);
+				circleCollide[other.shape](collision, cid, self, velocity, other);
 				break;
 			}
 			case RECT: {
-				rectCollide[other.shape](collision, cid);
+				rectCollide[other.shape](collision, cid, self, velocity, other);
 				break;
 			}
 			case POLYGON: {
-				polygonCollide[other.shape](collision, cid);
+				polygonCollide[other.shape](collision, cid, self, velocity, other);
 				break;
 			}
 		}

game/entities/hero/entity.ts

@@ -1,7 +1,7 @@
 import { defineEntity } from "#/engine/Entity.ts";
 import { keyboardInput } from "#/engine/Keyboard.ts";
 import { pointer } from "#/engine/Pointer.ts";
-import { createRect } from "#/engine/Rect.ts";
+import { createRect, fillRect, strokeRect } from "#/engine/Rect.ts";
 import $ from "#/engine/Scene.ts";
 import {
 	createSprite,
@@ -9,6 +9,8 @@ import {
 	defineSpriteSheet,
 } from "#/engine/Sprite.ts";
 import {
+	type Collider,
+	type Collision,
 	createCollider,
 	moveAndCollide,
 	Shape,
@@ -19,6 +21,7 @@ import {
 	scale,
 	type Vector,
 } from "#/engine/Vector.ts";
+import { viewport } from "#/engine/Viewport.ts";
 import charIdle from "#/game/assets/char-idle.png";
 
 const speed = 0.05;
@@ -35,6 +38,7 @@ const process = defineEntity("hero", {
 process((id, delta) => {
 	const position = $<Vector>("position").get(id)!.value;
 	const velocity = $<Vector>("velocity").get(id)!.value;
+	const collider = $<Collider>("collider").get(id)!.value;
 
 	if (pointer.isDown) {
 		position.x = pointer.position.x;
@@ -49,12 +53,18 @@ process((id, delta) => {
 	normalize(velocity);
 	scale(velocity, speed);
 
+	const collisions = moveAndCollide(id, velocity, delta);
+	// console.log(collisions);
+
 	position.x += velocity.x * delta;
 	position.y += velocity.y * delta;
 
 	velocity.x = 0;
 	velocity.y = 0;
 
-	const collisions = moveAndCollide(id, velocity, delta);
-	// console.log(collisions);
+	fillRect(viewport.ctx, collider.aabb, "orange");
+	strokeRect(viewport.ctx, collider.aabb, "red");
+	if (collisions.some((c: Collision) => c.cid.length > 0)) {
+		fillRect(viewport.ctx, collider.aabb, "red");
+	}
 });

game/entities/portal/entity.ts

@@ -1,5 +1,5 @@
 import { defineEntity } from "#/engine/Entity.ts";
-import { createRect } from "#/engine/Rect.ts";
+import { createRect, fillRect, strokeRect } from "#/engine/Rect.ts";
 import $ from "#/engine/Scene.ts";
 import {
 	createSprite,
@@ -12,6 +12,7 @@ import {
 	Shape,
 } from "#/engine/system/physics.ts";
 import { createVector, type Vector } from "#/engine/Vector.ts";
+import { viewport } from "#/engine/Viewport";
 import portal from "#/game/assets/portal.png";
 
 const portalSrc = await defineSpriteSheet(portal, 3, 1);
@@ -30,4 +31,7 @@ process((id, delta) => {
 
 	cPos.x = position.x;
 	cPos.y = position.y;
+
+	fillRect(viewport.ctx, collider.aabb, "orange");
+	strokeRect(viewport.ctx, collider.aabb, "red");
 });

game/scenes/testScene/data.json

@@ -16,8 +16,8 @@
 			"name": "portal",
 			"init": {
 				"position": {
-					"x": 16,
-					"y": 16
+					"x": 24,
+					"y": 24
 				}
 			}
 		},