Procedural landscape demo on OUYA/Android

A glitchy procedural, infinite-ish landscape demo running on Android and OUYA. Use the left joystick to move around on OUYA, or swiping on Android devices with touchscreens. Here’s the apk, and the source is here.

Screenshot_2014-01-06-07-18-45

It’s great to be able to have a single binary that works across all these devices – from OUYA’s TV screen sizes to phones, and using the standard gesture interface at the same time as the OUYA controller.

The graphics are programmed in Jellyfish Lisp, using Perlin noise to create the landscape. The language is probably still a bit too close to the underlying bytecode in places, but the function calling is working and it’s getting easier to write and experiment with the code.

(define terrain
  '(let ((vertex positions-start)
         (flingdamp (vector 0 0 0))
         (world (vector 0 0 0)))

     ;; recycle a triangle which is off the screen
     (define recycle 
       (lambda (dir)         
         ;; shift along x and y coordinates:
         ;; set z to zero for each vertex
         (write! vertex       
                 (+ (*v (read vertex) 
                        (vector 1 1 0)) dir))
         (write! (+ vertex 1) 
                 (+ (*v (read (+ vertex 1)) 
                        (vector 1 1 0)) dir))
         (write! (+ vertex 2) 
                 (+ (*v (read (+ vertex 2)) 
                        (vector 1 1 0)) dir))

         ;; get the perlin noise values for each vertex
         (let ((a (noise (* (- (read vertex) world) 0.2)))
               (b (noise (* (- (read (+ vertex 1)) 
                               world) 0.2)))
               (c (noise (* (- (read (+ vertex 2))
                               world) 0.2))))

           ;; set the z coordinate for height
           (write! vertex 
                   (+ (read vertex) 
                      (+ (*v a (vector 0 0 8)) 
                         (vector 0 0 -4))))
           (write! (+ vertex 1) 
                   (+ (read (+ vertex 1)) 
                      (+ (*v b (vector 0 0 8)) 
                         (vector 0 0 -4))))
           (write! (+ vertex 2) 
                   (+ (read (+ vertex 2)) 
                      (+ (*v c (vector 0 0 8)) 
                         (vector 0 0 -4))))

           ;; recalculate normals
           (define n (normalise 
                      (cross (- (read vertex)
                                (read (+ vertex 2)))
                             (- (read vertex)
                                (read (+ vertex 1))))))

           ;; write to normal data
           (write! (+ vertex 512) n)
           (write! (+ vertex 513) n)
           (write! (+ vertex 514) n)

           ;; write the z height as texture coordinates
           (write! (+ vertex 1536) 
                   (*v (swizzle zzz a) (vector 0 5 0)))          
           (write! (+ vertex 1537) 
                   (*v (swizzle zzz b) (vector 0 5 0)))          
           (write! (+ vertex 1538) 
                   (*v (swizzle zzz c) (vector 0 5 0))))))

     ;; forever
     (loop 1
       ;; add inertia to the fling/gamepad joystick input
       (set! flingdamp (+ (* flingdamp 0.99)
                          (*v
                           (read reg-fling)
                           (vector 0.01 -0.01 0))))

       (define vel (* flingdamp 0.002))
       ;; update the world coordinates
       (set! world (+ world vel))

       ;; for each vertex
       (loop (< vertex positions-end)         

         ;; update the vertex position
         (write! vertex (+ (read vertex) vel))
         (write! (+ vertex 1) (+ (read (+ vertex 1)) vel))
         (write! (+ vertex 2) (+ (read (+ vertex 2)) vel))

         ;; check for out of area polygons to recycle 
         (cond
          ((> (read vertex) 5.0)
           (recycle (vector -10 0 0)))         
          ((< (read vertex) -5.0)
           (recycle (vector 10 0 0))))
         
         (cond
          ((> (swizzle yzz (read vertex)) 4.0)
           (recycle (vector 0 -8 0)))
          ((< (swizzle yzz (read vertex)) -4.0)
           (recycle (vector 0 8 0))))

         (set! vertex (+ vertex 3)))
       (set! vertex positions-start))))

This lisp program compiles to 362 vectors of bytecode at startup, and runs well even on my cheap Android tablet. The speed seems close enough to native C++ to be worth the effort, and it's much more flexible (i.e. future livecoding/JIT compilation possibilities). The memory layout is shown below, it's packing executable instructions and model data into the same address space and doesn't use any memory allocation while it's running (no garbage collection and not even any C mallocs). The memory size is configurable but the nature of the system is such that it would be possible to put executable data into unused graphics sections (eg. normals or vertex colours), if appropriate.

jvm

Creative Commons License
This work, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

5 thoughts on “Procedural landscape demo on OUYA/Android

  1. Looks like downloading from the browser works, but I can’t see a way to get to the downloads directory to actually install the download. Via command line and usb cable “adb install jellyfish-release.apk” should work, but that requires the dev tools :(

  2. Wow! Please post more on this, I’ll be trawling your archives after work for more info on this. It seems very cool!

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>