Capturing keyboard input using O3D is pretty straightforward. The principle is the create a listener which listens for key presses, and then passes them on to a handler which executes whatever that key press needs to do. mybloggingplanet.com
So, the first thing to do is to add the handler function. What it does is rotates the 3D root by the amount specified by delta. It also sets the actionTaken flag to true if the key was processed and then returns that to the calling function.
function keyPressedAction(keyPressed, delta) {
var actionTaken = false;
switch(keyPressed) {
case 'a':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationY(-delta));
actionTaken = true;
break;
case 'd':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationY(delta));
actionTaken = true;
break;
case 'w':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationX(-delta));
actionTaken = true;
break;
case 's':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationX(delta));
actionTaken = true;
break;
}
return actionTaken;
}
The actual key press listener is keyPressedCallback. It first checks if the key was an accelerator key, which is then ignored. Next the character pressed is retrieved and converted to lowercase since we want to ignore Caps Lock. We then pass the character to the handler with the amount we want to rotate by, which we have set by a global variable. If the key press was handled, then we need to cancel the event, otherwise we ignore the key and let the keypress do what the browser normally let’s it do.
function keyPressedCallback(event) {
event = event || window.event;
if (event.metaKey)
return;
var keyChar =String.fromCharCode(o3djs.event.getEventKeyChar(event));
keyChar = keyChar.toLowerCase();
if (keyPressedAction(keyChar, g_keyPressDelta)) {
o3djs.event.cancel(event);
}
}
Now in the initialisation function, we need to add the key listener
window.document.onkeypress = keyPressedCallback;
Now, you should be able to rotate the cube up and down, and left and right, using the W, A, S, D keys.
The full listing for the tutorial is as follows
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Tutorial 5: Capturing keyboard input</title>
<script type="text/javascript" src="o3djs/base.js"></script>
<script type="text/javascript">
o3djs.require('o3djs.util');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.canvas');
// Events
// Run the init() function once the page has finished loading.
// Run the uninit() function when the page has is unloaded.
window.onload = init;
window.onunload = uninit;
// global variables
var g_o3d;
var g_math;
var g_client;
var g_pack;
var g_clock = 0;
var g_timeMult = 1;
var g_cubeTransform;
var g_textCanvas;
var g_paint;
var g_canvasLib;
var g_3dRoot;
var g_hudRoot;
var g_viewInfo;
var g_hudViewInfo;
var g_keyPressDelta = 0.05;
function createCube(material) {
var cubeShape = g_pack.createObject('Shape');
var cubePrimitive = g_pack.createObject('Primitive');
var streamBank = g_pack.createObject('StreamBank');
cubePrimitive.material = material;
cubePrimitive.owner = cubeShape;
cubePrimitive.streamBank = streamBank;
cubePrimitive.primitiveType = g_o3d.Primitive.TRIANGLELIST;
cubePrimitive.numberPrimitives = 12; // 12 triangles
cubePrimitive.numberVertices = 8; // 8 vertices in total
var positionArray = [
-0.5, -0.5, 0.5, // vertex 0
0.5, -0.5, 0.5, // vertex 1
-0.5, 0.5, 0.5, // vertex 2
0.5, 0.5, 0.5, // vertex 3
-0.5, 0.5, -0.5, // vertex 4
0.5, 0.5, -0.5, // vertex 5
-0.5, -0.5, -0.5, // vertex 6
0.5, -0.5, -0.5 // vertex 7
];
var indicesArray = [
0, 1, 2, // face 1
2, 1, 3,
2, 3, 4, // face 2
4, 3, 5,
4, 5, 6, // face 3
6, 5, 7,
6, 7, 0, // face 4
0, 7, 1,
1, 7, 3, // face 5
3, 7, 5,
6, 0, 4, // face 6
4, 0, 2
];
var positionsBuffer = g_pack.createObject('VertexBuffer');
var positionsField = positionsBuffer.createField('FloatField', 3);
positionsBuffer.set(positionArray);
var indexBuffer = g_pack.createObject('IndexBuffer');
indexBuffer.set(indicesArray);
streamBank.setVertexStream(
g_o3d.Stream.POSITION, // This stream stores vertex positions
0, // First (and only) position stream
positionsField, // field: the field this stream uses.
0); // start_index
// Associate the triangle indices Buffer with the primitive.
cubePrimitive.indexBuffer = indexBuffer;
return cubeShape;
}
function drawText(str) {
// Clear to completely transparent.
g_textCanvas.canvas.clear([0.5, 0.5, 0.5, 0.5]);
// Reuse the global paint object
var paint = g_paint;
paint.color = [1, 1, 1, 1];
paint.textSize = 12;
paint.textTypeface = 'Comic Sans MS';
paint.textAlign = g_o3d.CanvasPaint.LEFT;
paint.shader = null;
g_textCanvas.canvas.drawText(str, 10, 30, paint);
g_textCanvas.updateTexture();
}
/**
* This method gets called every time O3D renders a frame. Here's
* where we update the cube's transform to make it spin.
* @param {o3d.RenderEvent} renderEvent The render event object that
* gives us the elapsed time since the last time a frame was rendered.
*/
function renderCallback(renderEvent) {
g_clock += renderEvent.elapsedTime * g_timeMult;
drawText("Hello world - " + (Math.round(g_clock * 100) / 100) + "s");
}
/**
* Function performing the rotate action in response to a key-press.
* Rotates the scene based on key pressed. (w ,s, a, d). Note that the
* x, y-axis referenced here are relative to the current view of scene.
* @param {keyPressed} The letter pressed, in lower case.
* @param {delta} The angle by which the scene should be rotated.
* @return true if an action was taken.
*/
function keyPressedAction(keyPressed, delta) {
var actionTaken = false;
switch(keyPressed) {
case 'a':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationY(-delta));
actionTaken = true;
break;
case 'd':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationY(delta));
actionTaken = true;
break;
case 'w':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationX(-delta));
actionTaken = true;
break;
case 's':
g_3dRoot.localMatrix =
g_math.matrix4.mul(g_3dRoot.localMatrix,
g_math.matrix4.rotationX(delta));
actionTaken = true;
break;
}
return actionTaken;
}
/**
* Callback for the keypress event.
* Invokes the action to be performed for the key pressed.
* @param {event} keyPress event passed to us by javascript.
*/
function keyPressedCallback(event) {
event = event || window.event;
// Ignore accelerator key messages.
if (event.metaKey)
return;
var keyChar =String.fromCharCode(o3djs.event.getEventKeyChar(event));
// Just in case they have capslock on.
keyChar = keyChar.toLowerCase();
if (keyPressedAction(keyChar, g_keyPressDelta)) {
o3djs.event.cancel(event);
}
}
/**
* Creates the client area.
*/
function init() {
o3djs.util.makeClients(initStep2);
}
/**
* Initializes O3D.
* @param {Array} clientElements Array of o3d object elements.
*/
function initStep2(clientElements) {
// Initializes global variables and libraries.
var o3dElement = clientElements[0];
g_client = o3dElement.client;
g_o3d = o3dElement.o3d;
g_math = o3djs.math;
// Initialize O3D sample libraries.
o3djs.base.init(o3dElement);
// Create a pack to manage the objects created.
g_pack = g_client.createPack();
// Create 2 root transforms, one for the 3d parts and 2d parts.
// This is not strictly neccassary but it is helpful.
g_3dRoot = g_pack.createObject('Transform');
g_hudRoot = g_pack.createObject('Transform');
// Create the render graph for a view.
g_viewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_3dRoot,
g_client.renderGraphRoot);
// Set the background color to black.
g_viewInfo.clearBuffer.clearColor = [0, 0, 0, 1];
// Create a second view for the hud.
g_hudViewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_hudRoot,
g_client.renderGraphRoot);
// Make sure the hud gets drawn after the 3d stuff
g_hudViewInfo.root.priority = g_viewInfo.root.priority + 1;
// Turn off clearing the color for the hud since that would erase the
// 3d parts but leave clearing the depth and stencil so the HUD is
// unaffected by anything done by the 3d parts.
g_hudViewInfo.clearBuffer.clearColorFlag = false;
// Set up a perspective view
g_viewInfo.drawContext.projection = g_math.matrix4.perspective(
g_math.degToRad(30), // 30 degree fov.
g_client.width / g_client.height,
1, // Near plane.
5000); // Far plane.
// Set up our view transformation to look towards the world origin
// where the cube is located.
g_viewInfo.drawContext.view = g_math.matrix4.lookAt([0, 1, 5], //eye
[0, 0, 0], // target
[0, 1, 0]); // up
//Set up the 2d orthographic view
g_hudViewInfo.drawContext.projection = g_math.matrix4.orthographic(
0 + 0.5,
g_client.width + 0.5,
g_client.height + 0.5,
0 + 0.5,
0.001,
1000);
g_hudViewInfo.drawContext.view = g_math.matrix4.lookAt(
[0, 0, 1], // eye
[0, 0, 0], // target
[0, 1, 0]); // up
// Create an Effect object and initialize it using the shaders
// from the text area.
var redEffect = g_pack.createObject('Effect');
var shaderString = document.getElementById('effect').value;
redEffect.loadFromFXString(shaderString);
// Create a Material for the mesh.
var redMaterial = g_pack.createObject('Material');
// Set the material's drawList.
redMaterial.drawList = g_viewInfo.performanceDrawList;
// Apply our effect to this material. The effect tells the 3D
// hardware which shaders to use.
redMaterial.effect = redEffect;
// Create the Shape for the cube mesh and assign its material.
var cubeShape = createCube(redMaterial);
// Create a new transform and parent the Shape under it.
g_cubeTransform = g_pack.createObject('Transform');
g_cubeTransform.addShape(cubeShape);
// Parent the cube's transform to the client root.
g_cubeTransform.parent = g_3dRoot;
// Generate the draw elements for the cube shape.
cubeShape.createDrawElements(g_pack, null);
// Create the global paint object that's used by draw operations.
g_paint = g_pack.createObject('CanvasPaint');
// Creates an instance of the canvas utilities library.
g_canvasLib = o3djs.canvas.create(g_pack, g_hudRoot, g_hudViewInfo);
// Create a canvas that will be used to display the text.
g_textCanvas = g_canvasLib.createXYQuad(70, 70, 0, 100, 50, true);
// Set our render callback for animation.
// This sets a function to be executed every time frame is rendered.
g_client.setRenderCallback(renderCallback);
//Set up a callback to interpret keypresses
window.document.onkeypress = keyPressedCallback;
}
/**
* Removes callbacks so they aren't called after the page has unloaded.
*/
function uninit() {
if (g_client) {
g_client.cleanup();
}
}
</script>
</head>
<body>
<h1>Tutorial 5: Capturing keyboard input</h1>
Use W, S, A, D to rotate the cube
<br/>
<div id="o3d" style="width: 300px; height: 300px;"></div>
<div style="display:none">
<!-- Start of effect -->
<textarea id="effect">
// World View Projection matrix that will transform
// the input vertices to screen space.
float4x4 worldViewProjection : WorldViewProjection;
// input parameters for our vertex shader
struct VertexShaderInput {
float4 position : POSITION;
};
// input parameters for our pixel shader
struct PixelShaderInput {
float4 position : POSITION;
};
/**
* The vertex shader simply transforms input vertices to screen space
*/
PixelShaderInput vertexShaderFunction(VertexShaderInput input) {
PixelShaderInput output;
// Multiply the vertex positions by the worldViewProjection
// matrix to transform them to screen space.
output.position = mul(input.position, worldViewProjection);
return output;
}
/**
* This pixel shader just returns the color red.
*/
float4 pixelShaderFunction(PixelShaderInput input): COLOR {
return float4(1, 0, 0, 1); // Red.
}
// Here we tell our effect file *which* functions are
// our vertex and pixel shaders.
// #o3d VertexShaderEntryPoint vertexShaderFunction
// #o3d PixelShaderEntryPoint pixelShaderFunction
// #o3d MatrixLoadOrder RowMajor
</textarea>
<!-- End of effect -->
</div>
</body>
</html>
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