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Added a gitignore file and readme

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1 parent a23bca9 commit 2fcc969e7a30d78c96f234e633a60a26732364e9 @josephg josephg committed Dec 24, 2011
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+*.swp
+.DS_Store
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+# Chipmunk for Javascript!
+
+This is a port of the [Chipmunk Physics](http://chipmunk-physics.net/) library to Javascript!
+
+Its not complete.
+
+## Caveats
+
+- Some features are not implemented. Namely:
+ - The spatial hash - based space
+ - Joints. (The infrastructure is there, but the joints themselves haven't been ported yet)
+- It is much slower than the C version (duh, its in javascript). Specifically, physics simulations using chipmunk-js run between 3-7 times slower than the C equivalent. I expect to make big improvements to that over the next few months.
+
+# Usage
+
+The API for Chipmunk-js is almost identical to chipmunk-physics. Except:
+
+- The `cp` prefix has gone
+- Most functions are wrapped by their containing objects
+- Some functions took an array-and-length. Arrays are now all simply javascript arrays, and the length argument has been removed. Eg:
+
+ ```c
+cpMomentForPoly(mass, numVerts, *verts, offset);
+ ```
+
+ is now simply:
+
+ ```javascript
+momentForPoly(mass, verts, offset);
+ ```
+
+## Example
+
+This code creates a new space, sets 10 physics iterations per update (these increase simulation stability). Then it adds a bunch of line segments to the space.
+
+In C, this code looked like:
+
+```C
+ space = cpSpaceNew();
+ space->iterations = 10;
+
+ cpVect offset = cpv(-320, -240);
+ for(int i=0; i<(bouncy_terrain_count - 1); i++){
+ cpVect a = bouncy_terrain_verts[i], b = bouncy_terrain_verts[i+1];
+ cpShape *shape = cpSpaceAddShape(space, cpSegmentShapeNew(space->staticBody, cpvadd(a, offset), cpvadd(b, offset), 0.0f));
+ cpShapeSetElasticity(shape, 1.0f);
+ }
+```
+
+In javascript, the equivalent code is:
+
+```javascript
+ space = new cp.Space();
+ space.iterations = 10;
+
+ var offset = new cp.Vect(-320, -240);
+ for(var i=0; i<(bouncy_terrain_verts.length - 1); i++){
+ var a = bouncy_terrain_verts[i], b = bouncy_terrain_verts[i+1];
+ var shape = space.addShape(new cp.SegmentShape(space.staticBody, cp.vadd(a, offset), cp.vadd(b, offset), 0));
+ shape.setElasticity(1);
+ }
+```
+
+# License
+
+Like Chipmunk, chipmunk-js is MIT licensed.
+
+```
+Copyright (c) 2007 Scott Lembcke and Joseph Gentle
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+```

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