From 05b47f7a8c5451f858dc220df0e3a97542edace6 Mon Sep 17 00:00:00 2001 From: "gspencer@google.com" Date: Wed, 27 May 2009 23:15:42 +0000 Subject: This is the O3D source tree's initial commit to the Chromium tree. It is not built or referenced at all by the chrome build yet, and doesn't yet build in it's new home. We'll change that shortly. git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17035 0039d316-1c4b-4281-b951-d872f2087c98 --- o3d/samples/juggler.html | 431 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 431 insertions(+) create mode 100644 o3d/samples/juggler.html (limited to 'o3d/samples/juggler.html') diff --git a/o3d/samples/juggler.html b/o3d/samples/juggler.html new file mode 100644 index 0000000..3dc01f1 --- /dev/null +++ b/o3d/samples/juggler.html @@ -0,0 +1,431 @@ + + + + + + + + + Juggler Shader + + + + + + + + + + + +

Juggler

+ This sample displays a juggling pattern computed entirely in a shader. +

+ + + + +

+ +

+// 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.
+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);
+  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;
+}
+
+float 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) {
+  // The expression below is one minus a product.  The first factor in the
+  // product is responsible for balls moving from right to left, and the second
+  // factor is responsible for balls moving from left to right.
+  return 1 -
+    (1 - drawBallsInArc(pi, offset, right_hand, left_hand, height_factor,
+        baseline, ball_radius_2, hand_swing_radius, Z, threshold)) *
+    (1 - drawBallsInArc(pi, offset + 1, left_hand, right_hand, height_factor,
+        baseline, ball_radius_2, -hand_swing_radius, Z, threshold));
+}
+
+/**
+ * pixelShaderMain - pixel shader
+ */
+
+float4 pixelShaderMain(PixelShaderInput input) : COLOR {
+  const float pi = 3.14159265;
+  const float baseline = -1.2;
+  const float2 right_hand = float2(0.8, baseline);
+  const float2 left_hand = float2(-0.8, baseline);
+  const float hand_swing_radius = 0.3;
+  const float hand_radius_2 = 0.15 * 0.15;
+  const float ball_radius_2 = 0.1 * 0.1;
+
+  const float4 ball_color = float4(1, 1, 1, 1);
+  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;
+
+  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.
+  result += (1 - result.a) * (
+      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;
+  }
+  result += (1 - result.a) * ball_color *
+      clamp((ball_radius_2 - length_2(Z - hand)) / threshold, 0, 1);
+
+  float4 offset = float4(0, 2, 4, 6);
+
+  // For each of up-to-4 pairs of balls you want to add, increment offsets by
+  // (8, 8, 8, 8) and call drawAirborneBalls again.
+
+  // Draw airborne balls.
+  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
+

+ + -- cgit v1.1