Android rayshader sample.

samples/android_sample/assets/dart/main.dart

Index: samples/android_sample/assets/dart/main.dart
===================================================================
--- samples/android_sample/assets/dart/main.dart	(revision 0)
+++ samples/android_sample/assets/dart/main.dart	(revision 0)
@@ -0,0 +1,358 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "dart:math" as Math;
+import "android_extension.dart";
+
+const FRAGMENT_PROGRAM = """
+  precision mediump float;
+
+  const vec3 lightDir = vec3(0.577350269, 0.577350269, -0.577350269);
+  varying vec3 vPosition;
+  uniform vec3 cameraPos;
+  uniform vec3 sphere1Center;
+  uniform vec3 sphere2Center;
+  uniform vec3 sphere3Center;
+
+  bool intersectSphere(vec3 center, vec3 lStart, vec3 lDir,
+                       out float dist) {
+    vec3 c = center - lStart;
+    float b = dot(lDir, c);
+    float d = b*b - dot(c, c) + 1.0;
+    if (d < 0.0) {
+      dist = 10000.0;
+      return false;
+    }
+
+    dist = b - sqrt(d);
+    if (dist < 0.0) {
+      dist = 10000.0;
+      return false;
+    }
+
+    return true;
+  }
+
+  vec3 lightAt(vec3 N, vec3 V, vec3 color) {
+    vec3 L = lightDir;
+    vec3 R = reflect(-L, N);
+
+    float c = 0.3 + 0.4 * pow(max(dot(R, V), 0.0), 30.0) + 0.7 * dot(L, N);
+
+    if (c > 1.0) {
+      return mix(color, vec3(1.6, 1.6, 1.6), c - 1.0);
+    }
+
+    return c * color;
+  }
+
+  bool intersectWorld(vec3 lStart, vec3 lDir, out vec3 pos,
+                      out vec3 normal, out vec3 color) {
+    float d1, d2, d3;
+    bool h1, h2, h3;
+
+    h1 = intersectSphere(sphere1Center, lStart, lDir, d1);
+    h2 = intersectSphere(sphere2Center, lStart, lDir, d2);
+    h3 = intersectSphere(sphere3Center, lStart, lDir, d3);
+
+    if (h1 && d1 < d2 && d1 < d3) {
+      pos = lStart + d1 * lDir;
+      normal = pos - sphere1Center;
+      color = vec3(0.0, 0.0, 0.9);
+      if (fract(pos.x / 1.5) > 0.5 ^^
+          fract(pos.y / 1.5) > 0.5 ^^
+          fract(pos.z / 1.5) > 0.5) {
+        color = vec3(1.0, 0.0, 1.0);
+      }
+      else {
+        color = vec3(1.0, 1.0, 0.0);
+      }
+    }
+    else if (h2 && d2 < d3) {
+      pos = lStart + d2 * lDir;
+      normal = pos - sphere2Center;
+      color = vec3(0.9, mod(normal.y * 2.5, 1.0), 0.0);
+    }
+    else if (h3) {
+      pos = lStart + d3 * lDir;
+      normal = pos - sphere3Center;
+      color = vec3(0.0, clamp(sphere3Center.y/1.5, 0.0, 0.9),
+                   clamp(0.9 - sphere3Center.y/1.5, 0.0, 0.9));
+    }
+    else if (lDir.y < -0.01) {
+      pos = lStart + ((lStart.y + 2.7) / -lDir.y) * lDir;
+      if (pos.x*pos.x + pos.z*pos.z > 30.0) {
+        return false;
+      }
+      normal = vec3(0.0, 1.0, 0.0);
+      if (fract(pos.x / 5.0) > 0.5 == fract(pos.z / 5.0) > 0.5) {
+        color = vec3(1.0);
+      }
+      else {
+        color = vec3(0.0);
+      }
+    }
+    else {
+     return false;
+    }
+
+    return true;
+  }
+
+  void main(void)
+  {
+    vec3 cameraDir = normalize(vPosition - cameraPos);
+
+    vec3 p1, norm, p2;
+    vec3 col, colT, colM, col3;
+    if (intersectWorld(cameraPos, cameraDir, p1,
+                       norm, colT)) {
+      col = lightAt(norm, -cameraDir, colT);
+      colM = (colT + vec3(0.2)) / 1.2;
+      cameraDir = reflect(cameraDir, norm);
+      if (intersectWorld(p1, cameraDir, p2, norm, colT)) {
+        col += lightAt(norm, -cameraDir, colT) * colM;
+        colM *= (colT + vec3(0.2)) / 1.2;
+        cameraDir = reflect(cameraDir, norm);
+        if (intersectWorld(p2, cameraDir, p1, norm, colT)) {
+          col += lightAt(norm, -cameraDir, colT) * colM;
+        }
+      }
+
+      gl_FragColor = vec4(col, 1.0);
+    }
+    else {
+      gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
+    }
+  }
+""";
+
+const VERTEX_PROGRAM = """
+  attribute vec2 aVertexPosition;
+  attribute vec3 aPlotPosition;
+
+  varying vec3 vPosition;
+
+  void main(void)
+  {
+    gl_Position = vec4(aVertexPosition, 1.0, 1.0);
+    vPosition = aPlotPosition;
+ }
+""";
+
+loadShader(final type, final program) {
+  final shader = gl.createShader(type);
+  gl.shaderSource(shader, program);
+  gl.compileShader(shader);
+  if (gl.getShaderParameter(shader, WebGLRenderingContext.COMPILE_STATUS)
+      != WebGLRenderingContext.TRUE) {
+    log("Could not compile shader: ${gl.getShaderInfoLog(shader)}");
+    throw new Exception("Could not compile shader");
+  }
+  
+  return shader;
+}
+
+var shaderProgram;
+var aVertexPosition;
+var aPlotPosition;
+var cameraPos;
+var sphere1Center;
+var sphere2Center;
+var sphere3Center;
+var ratio;
+
+initShaders() {
+  var vertexShader = loadShader(WebGLRenderingContext.VERTEX_SHADER,
+      VERTEX_PROGRAM);
+  var fragmentShader = loadShader(WebGLRenderingContext.FRAGMENT_SHADER,
+      FRAGMENT_PROGRAM);
+
+  shaderProgram = gl.createProgram();
+  if (shaderProgram == 0) {
+    throw new Exception("Could not create program.");
+  }
+
+  gl.attachShader(shaderProgram, vertexShader);
+  gl.attachShader(shaderProgram, fragmentShader);
+  gl.linkProgram(shaderProgram);
+
+  if (gl.getProgramParameter(shaderProgram, WebGLRenderingContext.LINK_STATUS)
+      != WebGLRenderingContext.TRUE) {
+    log("Could not link program: ${gl.getProgramInfoLog(shaderProgram)}");
+    throw new Exception("Could not initialize shaders");
+  }
+  
+  gl.useProgram(shaderProgram);
+
+  aVertexPosition = gl.getAttribLocation(shaderProgram, "aVertexPosition");
+  gl.enableVertexAttribArray(aVertexPosition);
+
+  aPlotPosition = gl.getAttribLocation(shaderProgram, "aPlotPosition");
+  gl.enableVertexAttribArray(aPlotPosition);
+
+  cameraPos = gl.getUniformLocation(shaderProgram, "cameraPos");
+  sphere1Center = gl.getUniformLocation(shaderProgram, "sphere1Center");
+  sphere2Center = gl.getUniformLocation(shaderProgram, "sphere2Center");
+  sphere3Center = gl.getUniformLocation(shaderProgram, "sphere3Center");
+}
+
+initBuffers() {
+  var vertexPositionBuffer = gl.createBuffer();
+  gl.bindBuffer(WebGLRenderingContext.ARRAY_BUFFER, vertexPositionBuffer);
+  var vertices = [
+                  1.0,  1.0,
+                  -1.0,  1.0,
+                  1.0, -1.0,
+                  -1.0, -1.0,
+                  ];
+
+  gl.bufferData(WebGLRenderingContext.ARRAY_BUFFER, vertices,

[vsm, 2012/11/30 17:00:30]

Can you add a TODO above this line that vertices should be a Float32Array to
make it consistent with WebGL?

[gram, 2012/11/30 18:01:31]

Done.

+      WebGLRenderingContext.STATIC_DRAW);
+  gl.bindBuffer(WebGLRenderingContext.ARRAY_BUFFER, vertexPositionBuffer);
+  gl.vertexAttribPointer(aVertexPosition, 2, WebGLRenderingContext.FLOAT,
+      false,0, 0);
+
+  var plotPositionBuffer = gl.createBuffer();
+  gl.bindBuffer(WebGLRenderingContext.ARRAY_BUFFER, plotPositionBuffer);
+  gl.vertexAttribPointer(aPlotPosition, 3, WebGLRenderingContext.FLOAT,
+      false, 0, 0);
+}
+
+class Vector {
+  var x;
+  var y;
+  var z;
+  Vector(this.x, this.y, this.z);
+}

[Cutch, 2012/11/30 17:04:58]

You should be using vector_math instead of implementing your own vector types.
See the Solar 3D sample.

[gram, 2012/11/30 18:01:31]

I'll just add a TODO. This is a throwaway example and I don't want to expend
much effort on it.

+
+crossProd(v1, v2) {
+  return
+    new Vector(
+               v1.y*v2.z - v2.y*v1.z,
+               v1.z*v2.x - v2.z*v1.x,
+               v1.x*v2.y - v2.x*v1.y);
+}
+
+normalize(v) {
+  var l = Math.sqrt(v.x*v.x + v.y*v.y + v.z*v.z);
+  return new Vector( v.x/l, v.y/l, v.z/l );
+}
+
+vectAdd(v1, v2) {
+  return new Vector( v1.x + v2.x, v1.y + v2.y, v1.z + v2.z );
+}
+
+vectSub(v1, v2) {
+  return new Vector( v1.x - v2.x, v1.y - v2.y, v1.z - v2.z );
+}
+
+vectMul(v, l) {
+  return new Vector( v.x*l, v.y*l, v.z*l );
+}
+
+pushVec(v, arr) {
+  arr.addAll([v.x, v.y, v.z]);
+}
+
+var t = 0;
+int width, height;
+
+drawScene() {
+  var x1 = Math.sin(t * 1.1) * 1.5;
+  var y1 = Math.cos(t * 1.3) * 1.5;
+  var z1 = Math.sin(t + Math.PI/3) * 1.5;
+  var x2 = Math.cos(t * 1.2) * 1.5;
+  var y2 = Math.sin(t * 1.4) * 1.5;
+  var z2 = Math.sin(t*1.25 - Math.PI/3) * 1.5;
+  var x3 = Math.cos(t * 1.15) * 1.5;
+  var y3 = Math.sin(t * 1.37) * 1.5;
+  var z3 = Math.sin(t*1.27) * 1.5;
+
+  var cameraFrom = new Vector(
+                          Math.sin(t * 0.4) * 18,
+                          Math.sin(t * 0.13) * 5 + 5,
+                          Math.cos(t * 0.4) * 18 );
+  var cameraTo = new Vector(0.0, 0.0, 0.0);
+  var cameraPersp = 6.0;
+  var up = new Vector(0.0, 1.0, 0.0);
+  var cameraDir = normalize(vectSub(cameraTo, cameraFrom));
+
+  var cameraLeft = normalize(crossProd(cameraDir, up));
+  var cameraUp = normalize(crossProd(cameraLeft, cameraDir));
+  // cameraFrom + cameraDir * cameraPersp
+  var cameraCenter = vectAdd(cameraFrom, vectMul(cameraDir, cameraPersp));
+
+  // cameraCenter + cameraUp + cameraLeft * ratio
+  var cameraTopLeft  = vectAdd(vectAdd(cameraCenter, cameraUp),
+                               vectMul(cameraLeft, ratio));
+  var cameraBotLeft  = vectAdd(vectSub(cameraCenter, cameraUp),
+                               vectMul(cameraLeft, ratio));
+  var cameraTopRight = vectSub(vectAdd(cameraCenter, cameraUp),
+                               vectMul(cameraLeft, ratio));
+  var cameraBotRight = vectSub(vectSub(cameraCenter, cameraUp),
+                               vectMul(cameraLeft, ratio));
+
+  //corners = [1.2, 1, -12, -1.2, 1, -12, 1.2, -1, -12, -1.2, -1, -12];
+  var corners = [];
+  pushVec(cameraTopRight, corners);
+  pushVec(cameraTopLeft, corners);
+  pushVec(cameraBotRight, corners);
+  pushVec(cameraBotLeft, corners);
+
+  gl.bufferData(WebGLRenderingContext.ARRAY_BUFFER, corners,

[vsm, 2012/11/30 17:00:30]

Ditto on Float32Array.

[gram, 2012/11/30 18:01:31]

Done.

+      WebGLRenderingContext.STATIC_DRAW);
+
+  gl.uniform3f(cameraPos, cameraFrom.x, cameraFrom.y, cameraFrom.z);
+  gl.uniform3f(sphere1Center, x1, y1, z1);
+  gl.uniform3f(sphere2Center, x2, y2, z2);
+  gl.uniform3f(sphere3Center, x3, y3, z3);
+
+  gl.drawArrays(WebGLRenderingContext.TRIANGLE_STRIP, 0, 4);
+
+  t += 0.03;
+  if (t > Math.PI * 200) {
+    t -= Math.PI * 200;
+  }
+}
+
+setup(int w, int h) {
+  initShaders();
+  gl.clearColor(0.0, 0.0, 0.0, 1.0);
+  gl.clearDepth(1.0);
+  initBuffers();
+  resize(w, h);
+}
+
+resize(int w, int h) {
+  width = w;
+  height = h;
+  ratio = width / height;
+  gl.viewport(0, 0, width, height);
+  t -= 0.03;
+  drawScene();
+  return "resize $width $height";

[vsm, 2012/11/30 17:00:30]

Can you remove the return?  This was for my debugging before you added proper
logging.  :-)

[gram, 2012/11/30 18:01:31]

Done.

+}
+
+update() {
+  drawScene();
+  eglSwapBuffers();
+  return "draw";

[vsm, 2012/11/30 17:00:30]

Ditto.

[gram, 2012/11/30 18:01:31]

Done.

+}
+
+onMotionDown(double when, int x, int y) {

[vsm, 2012/11/30 17:00:30]

We typically use "num" instead of "double" so you can pass in int values as well
(unless it's perf sensitive).

[gram, 2012/11/30 18:01:31]

The NDK event is providing a double and this mirrors that. Based on that do you
still think I should make it a num?

[vsm, 2012/11/30 18:38:31]

The style guide suggests that we do:
http://www.dartlang.org/articles/style-guide/#type-annotations

But, it's not mandated, so up to you.

On 2012/11/30 18:01:31, gram wrote:

[gram, 2012/11/30 22:09:22]

Well, it turned out I had the doubles and ints mixed up anyway; when is an int
and x,y are doubles! So I'll make 'em nums and then I can't go wrong, can I? ;-)

+  t = (x / width) * Math.PI * 200;
+}
+
+onMotionUp(double when, int x, int y) {}
+onMotionMove(double when, int x, int y) {}
+onMotionCancel(double when, int x, int y) {}
+onMotionOutside(double when, int x, int y) {}
+onMotionPointerDown(double when, int x, int y) {}
+onMotionPointerUp(double when, int x, int y) {}
+onKeyDown(double when, int flags, int keycode, int metastate, int repeat) {}
+onKeyUp(double when, int flags, int keycode, int metastate, int repeat) {}
+onKeyMultiple(double when, int flags, int keycode, int metastate, int repeat) {
+}
+