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<!--
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modification, are permitted provided that the following conditions are
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notice, this list of conditions and the following disclaimer.
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-->
<!--
O3D Juggler
-->
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html style="width: 100%; height: 100%;">
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>
Juggler Shader
</title>
<script type="text/javascript" src="o3djs/base.js"></script>
<script type="text/javascript" id="o3d">
o3djs.require('o3djs.util');
o3djs.require('o3djs.math');
o3djs.require('o3djs.rendergraph');
o3djs.require('o3djs.primitives');
// Events
// Run the init() function once the page has finished loading.
// unload() when the page is unloaded.
window.onload = init;
window.onunload = unload;
// global variables
var g_o3d;
var g_math;
var g_client;
var g_o3dElement;
var g_viewInfo;
var g_pack;
var g_o3dWidth = -1;
var g_o3dHeight = -1;
var g_transform;
var g_clock = 0.0;
var g_timeMult = 1; // amount to multiply elapsed time by.
// Used to make the animation run faster or slower.
var g_finished = false; // for selenium testing
var g_thetaParam;
var g_numParam;
var g_numBalls; // Must be either 3, 5, 7, or 9 for now.
var g_speedScale; // Used to make higher numbers of balls animate faster.
/**
* Creates the client area.
*/
function init() {
o3djs.util.makeClients(initStep2);
}
/**
* Initializes O3D, loads the effect, and creates the square.
* @param {Array} clientElements Array of o3d object elements.
*/
function initStep2(clientElements) {
// Initialize global variables and libraries.
g_o3dElement = clientElements[0];
g_o3d = g_o3dElement.o3d;
g_math = o3djs.math;
g_client = g_o3dElement.client;
// Create a g_pack to manage our resources/assets
g_pack = g_client.createPack();
// Create the render graph for a view.
g_viewInfo = o3djs.rendergraph.createBasicView(
g_pack,
g_client.root,
g_client.renderGraphRoot,
[0, 0, 0, 1]);
var effect = g_pack.createObject('Effect');
effect.loadFromFXString(document.getElementById('shader').value);
// Create a Material for the effect.
var myMaterial = g_pack.createObject('Material');
// Apply our effect to this material.
myMaterial.effect = effect;
// Set the material's drawList for opaque objects.
myMaterial.drawList = g_viewInfo.performanceDrawList;
// Create the params the effect needs on the material.
effect.createUniformParameters(myMaterial);
// Create a square.
var myShape = o3djs.primitives.createPlane(g_pack, myMaterial,
1, 1, 1, 1);
// Set up the individual parameters in our effect file.
g_thetaParam = myMaterial.getParam('theta');
g_thetaParam.value = 0;
g_numParam = myMaterial.getParam('num');
updateNum();
// Set the position of the camera.
g_viewInfo.drawContext.view = g_math.matrix4.lookAt(
[0, 1, 0], //eye
[0, 0, 0], //target
[0, 0, -1]); //up
// Generate the projection matrix based
// on the g_o3d plugin size by calling resize().
resize();
// Now attach the square to the root of the transform graph.
g_client.root.addShape(myShape);
toggleRenderCallback();
g_finished = true; // for selenium testing.
}
function updateNum() {
var group = document.the_form.radio_group;
for (var i = 0; i < group.length; ++i) {
if (group[i].checked) {
setNumBalls(parseInt(group[i].value));
}
}
}
function toggleRenderCallback() {
var box = document.the_form.check_box;
if (box.checked) {
g_client.setRenderCallback(onrender);
} else {
g_client.clearRenderCallback();
}
}
function setNumBalls(num) {
g_numBalls = num;
g_numParam.value = g_numBalls;
g_speedScale = Math.sqrt(g_numBalls) * 5;
}
function onrender(render_event) {
g_clock += render_event.elapsedTime * g_timeMult;
g_thetaParam.value = g_clock * g_speedScale;
// If we don't check the size of the client area every frame we don't get a
// chance to adjust the perspective matrix fast enough to keep up with the
// browser resizing us, so onrender must call resize.
resize();
}
// Generates the projection matrix based on the size of the g_o3d plugin
// and calculates the view-projection matrix.
function resize() {
var newWidth = g_client.width;
var newHeight = g_client.height;
if (newWidth != g_o3dWidth || newHeight != g_o3dHeight) {
g_o3dWidth = newWidth;
g_o3dHeight = newHeight;
// Determine what the size of the rendered square within the client should
// be in pixels.
var side = g_o3dWidth < g_o3dHeight ?
g_o3dWidth : g_o3dHeight;
// Convert to the region of world space that must be enclosed by the
// orthographic projection.
var worldSize = g_math.divVectorScalar([g_o3dWidth, g_o3dHeight], side);
// Find a projection matrix to transform from world space to screen space.
g_viewInfo.drawContext.projection = o3djs.math.matrix4.orthographic(
-0.5 * worldSize[0], 0.5 * worldSize[0],
-0.5 * worldSize[1], 0.5 * worldSize[1],
0.5, 1.5);
}
}
/**
* Removes any callbacks so they don't get called after the page has unloaded.
*/
function unload() {
if (g_client) {
g_client.cleanup();
}
}
</script>
</head>
<body style="width: 95%; height: 95%;">
<table style="width: 100%; height: 100%;">
<tr>
<td>
<h1>Juggler</h1>
<p>
This sample displays a juggling pattern computed entirely in a shader.
<form name="the_form">
<input type="radio" name="radio_group" value="3"
onclick=updateNum()>3 Balls
<input type="radio" name="radio_group" value="5"
onclick=updateNum()>5 Balls
<input type="radio" name="radio_group" value="7"
onclick=updateNum()>7 Balls
<input type="radio" name="radio_group" value="9"
onclick=updateNum()>9 Balls
<input type="radio" name="radio_group" value="11" checked
onclick=updateNum()>11 Balls
<input type="radio" name="radio_group" value="13"
onclick=updateNum()>13 Balls
<input type="radio" name="radio_group" value="15"
onclick=updateNum()>15 Balls
<input type="radio" name="radio_group" value="17"
onclick=updateNum()>17 Balls
<input type="checkbox" name="check_box" checked
onclick=toggleRenderCallback()>Animate
</form>
</p>
<table id="container" style="width: 100%; height: 80%;">
<tr>
<td height="100%">
<!-- Start of g_o3d plugin -->
<div id="o3d" style="width: 100%; height: 100%;"></div>
<!-- End of g_o3d plugin -->
</td>
</tr>
</table>
<!-- a simple way to get a multiline string -->
<textarea id="shader" name="shader" cols="80" rows="20"
style="display: none;">
// The 4x4 world view projection matrix.
float4x4 worldViewProjection : WORLDVIEWPROJECTION;
float theta;
float num;
// input parameters for our vertex shader
struct VertexShaderInput {
float4 position : POSITION;
float2 texCoord : TEXCOORD0;
};
// input parameters for our pixel shader
// also the output parameters for our vertex shader
struct PixelShaderInput {
float4 position : POSITION;
float2 texCoord : TEXCOORD0;
float4 color : COLOR;
};
/**
* vertexShaderMain - our vertex shader for the juggling texture
*/
PixelShaderInput vertexShaderMain(VertexShaderInput input) {
PixelShaderInput output;
output.position = mul(input.position, worldViewProjection);
output.texCoord = 4.0 * (input.texCoord - float2(0.5, 0.5));
output.color = float4(1, 1, 1, 1);
return output;
}
float length_2(in float2 v) {
return dot(v, v);
}
// Draw the balls in a single arc.
// Returns 1 if the pixel is within a ball, 0 if it isn't, and a value in
// between for pixels right on the edge, for antialiasing.
float drawBallsInArc(in float pi,
in float4 offset,
in float2 source_hand,
in float2 dest_hand,
in float height_factor,
in float baseline,
in float ball_radius_2,
in float hand_throw_offset,
in float2 Z,
in float threshold) {
// Map theta from its current range of [0, 2 * num * pi) onto [0, (num - 1))
// by scaling, adding offset, and modding, then map that to [0, 1) by scaling.
// The first mapping tells us where in the repeating cycle we are, and the
// second mapping simplifies the calculation of the parabola.
// The vector offset is used to distinguish between balls in the same arc, but
// out of phase. At the beginning of this function, all the operations are
// vectorized to save instructions; we get to calculate 4 ball positions for
// the price of 1.
// The reason for the (num - 1) in the expression below is that with num
// balls, each ball spends (num - 1) beats in the air, then one in the hand.
// So (num - 1) is the length of time a parabola takes.
float4 time = fmod(theta / pi + offset, (num - 1)) / (num - 1);
float dx = dest_hand.x - source_hand.x;
float4 x = time * dx + source_hand.x - hand_throw_offset;
float4 y = time * (1 - time);
y = y * height_factor + baseline;
float4 ZX = Z.x;
float4 ZY = Z.y;
float4 len_2 = (ZX - x) * (ZX - x) + (ZY - y) * (ZY - y);
// This antialiasing fuzzes the balls just a bit larger than they would
// otherwise be.
float4 temp = clamp((len_2 - ball_radius_2) / threshold, 0, 1);
// One minus the product of all entries in temp.
temp.xy = temp.xy * temp.zw;
return 1 - temp.x * temp.y;
}
float4 drawAirborneBalls(in float pi,
in float4 offset,
in float2 right_hand,
in float2 left_hand,
in float height_factor,
in float baseline,
in float ball_radius_2,
in float hand_swing_radius,
in float2 Z,
in float threshold) {
float value =
// balls going right to left
(drawBallsInArc(pi, offset, right_hand, left_hand, height_factor,
baseline, ball_radius_2, hand_swing_radius, Z, threshold) +
// balls going left to right
drawBallsInArc(pi, offset + 1, left_hand, right_hand, height_factor,
baseline, ball_radius_2, -hand_swing_radius, Z, threshold));
return float4(value, value, value, value);
}
/**
* pixelShaderMain - pixel shader
*/
float4 pixelShaderMain(PixelShaderInput input) : COLOR {
const float pi = 3.14159265;
const float baseline = -1.4;
const float2 right_hand = float2(0.8, baseline);
const float2 left_hand = float2(-0.8, baseline);
const float hand_swing_radius = 0.25;
const float hand_radius = 0.15;
const float hand_radius_2 = hand_radius * hand_radius;
const float ball_radius = 0.08;
const float ball_radius_2 = ball_radius * ball_radius;
const float4 right_hand_color = float4(1, 0, 0, 1);
const float4 left_hand_color = float4(0, 0, 1, 1);
const float4 background_color = float4(0, 0, 0, 0);
const float threshold = 0.002; // Used in clamp for antialiasing.
float height_factor = num * 0.75;
float2 Z = input.texCoord;
// Coerce to the range [0, 2 * Pi * num].
float2 r_h = hand_swing_radius * float2(-cos(theta), sin(theta)) + right_hand;
float2 l_h = hand_swing_radius * float2(-cos(theta), -sin(theta)) + left_hand;
// Initialize color of pixel to background_color. Background color has an
// alpha of 0. Color of objects each have alpha 1, so multiplying by
// (1-alpha) before adding the color ensures that nothing gets overdrawn.
// It's kind of like a rudimentary z-buffer.
float4 result = background_color;
// Draw the hands. The antialiasing here fuzzes the hands just a little bit
// smaller than they would otherwise be. That's the opposite of what we do
// for the balls, just because it happens to be cheaper here to do smaller and
// cheaper in drawBallsInArc to do larger.
result +=
clamp((hand_radius_2 - length_2(Z - r_h)) / threshold, 0, 1) *
(Z.y < r_h.y) * right_hand_color +
clamp((hand_radius_2 - length_2(Z - l_h)) / threshold, 0, 1) *
(Z.y < l_h.y) * left_hand_color;
// Draw the ball in the hand. There is always a ball in exactly one hand, and
// which hand that is alternates.
float2 hand;
if (fmod(floor(theta / pi), 2) > 0.5) {
hand = r_h;
} else {
hand = l_h;
}
// The antialiasing here fuzzes the balls just a bit bigger than they would
// otherwise be. This is more work than making them smaller [the extra
// subtraction in the "1 - clamp..." below], but inverting it in
// drawBallsInArc would be more expensive, and they have to match so that the
// balls are all the same size.
result += (1 - result.a) *
(1 - clamp((length_2(Z - hand) - ball_radius_2) / threshold, 0, 1));
// Draw airborne balls.
float4 offset = float4(0, 2, 4, 6);
result += (1 - result.a) * drawAirborneBalls(pi,
offset,
right_hand,
left_hand,
height_factor,
baseline,
ball_radius_2,
hand_swing_radius,
Z,
threshold);
// For each up-to-4 pairs of balls you want to add, increment offset by
// (8, 8, 8, 8) and call drawAirborneBalls again.
offset += 8;
result += (1 - result.a) * drawAirborneBalls(pi,
offset,
right_hand,
left_hand,
height_factor,
baseline,
ball_radius_2,
hand_swing_radius,
Z,
threshold);
return result;
}
// Here we tell our effect file *which* functions are
// our vertex and pixel shaders.
// #o3d VertexShaderEntryPoint vertexShaderMain
// #o3d PixelShaderEntryPoint pixelShaderMain
// #o3d MatrixLoadOrder RowMajor
</textarea>
</td>
</tr>
</table>
</body>
</html>
|
