4 // A Javascript 2D vector library
6 // method that returns a float value do not modify the vector
7 // method that implement operators return a new vector with the modifications without
8 // modifying the calling vector or the parameters.
10 // v3 = v1.add(v2); // v3 is set to v1 + v2, v1, v2 are not modified
12 // methods that take a single vector as a parameter are usually also available with
13 // q '_xy' suffix. Those method takes two floats representing the x,y coordinates of
14 // the vector parameter and allow you to avoid to needlessly create a vector object :
16 // v2 = v1.add(new Vec2(3,4));
17 // v2 = v1.add_xy(3,4); //equivalent to previous line
19 // angles are in radians by default but method that takes angle as parameters
20 // or return angle values usually have a variant with a '_deg' suffix that works in degrees
23 // The 2D vector object
31 // Multiply a number expressed in radiant by rad2deg to convert it in degrees
32 var rad2deg = 57.29577951308232;
33 // Multiply a number expressed in degrees by deg2rad to convert it to radiant
34 var deg2rad = 0.017453292519943295;
35 // The numerical precision used to compare vector equality
36 var epsilon = 0.0000001;
38 // This static method creates a new vector from polar coordinates with the angle expressed
40 Vec2.new_polar_deg = function(len,angle){
41 var v = new Vec2(len,0);
42 return v.rotate_deg(angle);
44 // This static method creates a new vector from polar coordinates with the angle expressed in
46 Vec2.new_polar = function(len,angle){
47 var v = new Vec2(len,0);
51 // returns the length or modulus or magnitude of the vector
52 Vec2.prototype.len = function(){
53 return Math.sqrt(this.x*this.x + this.y*this.y);
55 // returns the squared length of the vector, this method is much faster than len()
56 Vec2.prototype.len_sq = function(){
57 return this.x*this.x + this.y*this.y;
59 // return the distance between this vector and the vector v
60 Vec2.prototype.dist = function(v){
61 var dx = this.x - v.x;
62 var dy = this.y - v.y;
63 return Math.sqrt(dx*dx + dy*dy);
65 // return the distance between this vector and the vector of coordinates (x,y)
66 Vec2.prototype.dist_xy = function(x,y){
69 return Math.sqrt(dx*dx + dy*dy);
71 // return the squared distance between this vector and the vector and the vector v
72 Vec2.prototype.dist_sq = function(v){
73 var dx = this.x - v.x;
74 var dy = this.y - v.y;
77 // return the squared distance between this vector and the vector of coordinates (x,y)
78 Vec2.prototype.dist_sq_xy = function(x,y){
83 // return the dot product between this vector and the vector v
84 Vec2.prototype.dot = function(v){
85 return this.x*v.x + this.y*v.y;
87 // return the dot product between this vector and the vector of coordinate (x,y)
88 Vec2.prototype.dot_xy = function(x,y){
89 return this.x*x + this.y*y;
91 // return a new vector with the same coordinates as this
92 Vec2.prototype.clone = function(){
93 return new Vec2(this.x,this.y);
95 // return the sum of this and vector v as a new vector
96 Vec2.prototype.add = function(v){
97 return new Vec2(this.x+v.x,this.y+v.y);
99 // return the sum of this and vector (x,y) as a new vector
100 Vec2.prototype.add_xy = function(x,y){
101 return new Vec2(this.x+x,this.y+y);
103 // returns (this - v) as a new vector where v is a vector and - is the vector substraction
104 Vec2.prototype.sub = function(v){
105 return new Vec2(this.x-v.x,this.y-v.y);
107 // returns (this - (x,y)) as a new vector where - is vector substraction
108 Vec2.prototype.sub_xy = function(x,y){
109 return new Vec2(this.x-x,this.y-y);
111 // return (this * v) as a new vector where v is a vector and * is the by component product
112 Vec2.prototype.mult = function(v){
113 return new Vec2(this.x*v.x,this.y*v.y);
115 // return (this * (x,y)) as a new vector where * is the by component product
116 Vec2.prototype.mult_xy = function(x,y){
117 return new Vec2(this.x*x,this.y*y);
119 // return this scaled by float f as a new fector
120 Vec2.prototype.scale = function(f){
121 return new Vec2(this.x*f, this.y*f);
123 // return the negation of this vector
124 Vec2.prototype.neg = function(f){
125 return new Vec2(-this.x,-this.y);
127 // return this vector normalized as a new vector
128 Vec2.prototype.normalize = function(){
129 var len = this.len();
131 return new Vec2(0,1);
133 return this.scale(1.0/len);
135 return new Vec2(this.x,this.y);
137 // return a new vector with the same direction as this vector of length float l. (negative values of l will invert direction)
138 Vec2.prototype.set_len = function(l){
139 return this.normalize().scale(l);
141 // return the projection of this onto the vector v as a new vector
142 Vec2.prototype.project = function(v){
143 return v.set_len(this.dot(v));
145 // return a string representation of this vector
146 Vec2.prototype.toString = function(){
155 //return this vector counterclockwise rotated by rad radians as a new vector
156 Vec2.prototype.rotate = function(rad){
157 var c = Math.cos(rad);
158 var s = Math.sin(rad);
159 var px = this.x * c - this.y *s;
160 var py = this.x * s + this.y *c;
161 return new Vec2(px,py);
163 //return this vector counterclockwise rotated by deg degrees as a new vector
164 Vec2.prototype.rotate_deg = function(deg){
165 return this.rotate(deg * deg2rad);
167 //linearly interpolate this vector towards the vector v by float factor alpha.
168 // alpha == 0 : does nothing
169 // alpha == 1 : sets this to v
170 Vec2.prototype.lerp = function(v,alpha){
171 var inv_alpha = 1 - alpha;
172 return new Vec2( this.x * inv_alpha + v.x * alpha,
173 this.y * inv_alpha + v.y * alpha );
175 // returns the angle between this vector and the vector (1,0) in radians
176 Vec2.prototype.angle = function(){
177 return Math.atan2(this.y,this.x);
179 // returns the angle between this vector and the vector (1,0) in degrees
180 Vec2.prototype.angle_deg = function(){
181 return Math.atan2(this.y,this.x) * rad2deg;
183 // returns true if this vector is equal to the vector v, with a tolerance defined by the epsilon module constant
184 Vec2.prototype.equals = function(v){
185 if(Math.abs(this.x-v.x) > epsilon){
187 }else if(Math.abs(this.y-v.y) > epsilon){
192 // returns true if this vector is equal to the vector (x,y) with a tolerance defined by the epsilon module constant
193 Vec2.prototype.equals_xy = function(x,y){
194 if(Math.abs(this.x-x) > epsilon){
196 }else if(Math.abs(this.y-y) > epsilon){
204 // A Bounding Shapes Library
207 // A Bounding Ellipse
208 // cx,cy : center of the ellipse
209 // rx,ry : radius of the ellipse
210 function BEllipse(cx,cy,rx,ry){
211 this.type = 'ellipse';
212 this.x = cx-rx; // minimum x coordinate contained in the ellipse
213 this.y = cy-ry; // minimum y coordinate contained in the ellipse
214 this.sx = 2*rx; // width of the ellipse on the x axis
215 this.sy = 2*ry; // width of the ellipse on the y axis
216 this.hx = rx; // half of the ellipse width on the x axis
217 this.hy = ry; // half of the ellipse width on the y axis
218 this.cx = cx; // x coordinate of the ellipse center
219 this.cy = cy; // y coordinate of the ellipse center
220 this.mx = cx + rx; // maximum x coordinate contained in the ellipse
221 this.my = cy + ry; // maximum x coordinate contained in the ellipse
223 window.BEllipse = BEllipse;
225 // returns an unordered list of vector defining the positions of the intersections between the ellipse's
226 // boundary and a line segment defined by the start and end vectors a,b
227 BEllipse.prototype.collide_segment = function(a,b){
228 // http://paulbourke.net/geometry/sphereline/
231 if(a.equals(b)){ //we do not compute the intersection in this case. TODO ?
235 // make all computations in a space where the ellipse is a circle
237 var c = new Vec2(this.cx,this.cy);
238 a = a.sub(c).mult_xy(1/this.hx,1/this.hy);
239 b = b.sub(c).mult_xy(1/this.hx,1/this.hy);
242 if(a.len_sq() < 1 && b.len_sq() < 1){ //both points inside the ellipse
246 // compute the roots of the intersection
248 var A = (ab.x*ab.x + ab.y*ab.y);
249 var B = 2*( ab.x*a.x + ab.y*a.y);
250 var C = a.x*a.x + a.y*a.y - 1;
251 var u = B * B - 4*A*C;
258 var u1 = (-B + u) / (2*A);
259 var u2 = (-B - u) / (2*A);
261 if(u1 >= 0 && u1 <= 1){
262 var pos = a.add(ab.scale(u1));
263 collisions.push(pos);
265 if(u1 != u2 && u2 >= 0 && u2 <= 1){
266 var pos = a.add(ab.scale(u2));
267 collisions.push(pos);
269 for(var i = 0; i < collisions.length; i++){
270 collisions[i] = collisions[i].mult_xy(this.hx,this.hy);
271 collisions[i] = collisions[i].add_xy(this.cx,this.cy);
276 // A bounding rectangle
277 // x,y the minimum coordinate contained in the rectangle
278 // sx,sy the size of the rectangle along the x,y axis
279 function BRect(x,y,sx,sy){
281 this.x = x; // minimum x coordinate contained in the rectangle
282 this.y = y; // minimum y coordinate contained in the rectangle
283 this.sx = sx; // width of the rectangle on the x axis
284 this.sy = sy; // width of the rectangle on the y axis
285 this.hx = sx/2; // half of the rectangle width on the x axis
286 this.hy = sy/2; // half of the rectangle width on the y axis
287 this.cx = x + this.hx; // x coordinate of the rectangle center
288 this.cy = y + this.hy; // y coordinate of the rectangle center
289 this.mx = x + sx; // maximum x coordinate contained in the rectangle
290 this.my = y + sy; // maximum x coordinate contained in the rectangle
293 window.BRect = BRect;
294 // Static method creating a new bounding rectangle of size (sx,sy) centered on (cx,cy)
295 BRect.new_centered = function(cx,cy,sx,sy){
296 return new BRect(cx-sx/2,cy-sy/2,sx,sy);
298 //intersect line a,b with line c,d, returns null if no intersection
299 function line_intersect(a,b,c,d){
300 // http://paulbourke.net/geometry/lineline2d/
301 var f = ((d.y - c.y)*(b.x - a.x) - (d.x - c.x)*(b.y - a.y));
306 var fab = ((d.x - c.x)*(a.y - c.y) - (d.y - c.y)*(a.x - c.x)) * f ;
307 if(fab < 0 || fab > 1){
310 var fcd = ((b.x - a.x)*(a.y - c.y) - (b.y - a.y)*(a.x - c.x)) * f ;
311 if(fcd < 0 || fcd > 1){
314 return new Vec2(a.x + fab * (b.x-a.x), a.y + fab * (b.y - a.y) );
317 // returns an unordered list of vector defining the positions of the intersections between the ellipse's
318 // boundary and a line segment defined by the start and end vectors a,b
320 BRect.prototype.collide_segment = function(a,b){
322 var corners = [ new Vec2(this.x,this.y), new Vec2(this.x,this.my),
323 new Vec2(this.mx,this.my), new Vec2(this.mx,this.y) ];
324 var pos = line_intersect(a,b,corners[0],corners[1]);
325 if(pos) collisions.push(pos);
326 pos = line_intersect(a,b,corners[1],corners[2]);
327 if(pos) collisions.push(pos);
328 pos = line_intersect(a,b,corners[2],corners[3]);
329 if(pos) collisions.push(pos);
330 pos = line_intersect(a,b,corners[3],corners[0]);
331 if(pos) collisions.push(pos);
335 // returns true if the rectangle contains the position defined by the vector 'vec'
336 BRect.prototype.contains_vec = function(vec){
337 return ( vec.x >= this.x && vec.x <= this.mx &&
338 vec.y >= this.y && vec.y <= this.my );
340 // returns true if the rectangle contains the position (x,y)
341 BRect.prototype.contains_xy = function(x,y){
342 return ( x >= this.x && x <= this.mx &&
343 y >= this.y && y <= this.my );
345 // returns true if the ellipse contains the position defined by the vector 'vec'
346 BEllipse.prototype.contains_vec = function(v){
347 v = v.mult_xy(this.hx,this.hy);
348 return v.len_sq() <= 1;
350 // returns true if the ellipse contains the position (x,y)
351 BEllipse.prototype.contains_xy = function(x,y){
352 return this.contains(new Vec2(x,y));