From 2ee2879188358c927dafd05617f32ba0320e7fb2 Mon Sep 17 00:00:00 2001
From: amandaghassaei <amandaghassaei@gmail.com>
Date: Sun, 2 Apr 2017 21:05:08 -0400
Subject: [PATCH] diffusion
---
index.html | 31 ++++++++++++++++++++++++++++++-
main.js | 37 +++++++++++++++++++++++++++----------
2 files changed, 57 insertions(+), 11 deletions(-)
diff --git a/index.html b/index.html
index f41143f..dad2cc8 100644
--- a/index.html
+++ b/index.html
@@ -29,7 +29,36 @@
}
</script>
- <script id="advectShader" type="x-shader/x-fragment">
+ <script id="diffuseShader" type="x-shader/x-fragment">
+ precision mediump float;
+
+ uniform sampler2D u_material;
+
+ uniform vec2 u_textureSize;
+
+ uniform float u_alpha;
+ uniform float u_reciprocalBeta;
+
+ void main() {
+
+ vec2 fragCoord = gl_FragCoord.xy;
+
+ vec2 currentState = texture2D(u_material, fragCoord/u_textureSize).xy;
+
+ //implicitly solve diffusion via jacobi iteration
+
+ vec2 n = texture2D(u_material, (fragCoord+vec2(0.0, 1.0))/u_textureSize).xy;
+ vec2 s = texture2D(u_material, (fragCoord+vec2(0.0, -1.0))/u_textureSize).xy;
+ vec2 e = texture2D(u_material, (fragCoord+vec2(1.0, 0.0))/u_textureSize).xy;
+ vec2 w = texture2D(u_material, (fragCoord+vec2(-1.0, 0.0))/u_textureSize).xy;
+
+ vec2 nextState = (n + s + e + w + u_alpha * currentState) * u_reciprocalBeta;
+
+ gl_FragColor = vec4(nextState, 0, 0);
+ }
+ </script>
+
+ <script id="advectShader" type="x-shader/x-fragment">
precision mediump float;
uniform sampler2D u_velocity;
diff --git a/main.js b/main.js
index 4e24ca7..64768ac 100755
--- a/main.js
+++ b/main.js
@@ -9,6 +9,10 @@ var mouseEnable = false;
var paused = false;//while window is resizing
+var dt = 1;
+var dx = 1;
+var nu = 1;//viscosity
+
var GPU;
window.onload = initGL;
@@ -39,10 +43,17 @@ function initGL() {
// setup a GLSL programs
GPU.createProgram("advect", "2d-vertex-shader", "advectShader");
GPU.setUniformForProgram("advect" ,"u_textureSize", [width, height], "2f");
- GPU.setUniformForProgram("advect", "u_dt", 1.0, "1f");
+ GPU.setUniformForProgram("advect", "u_dt", dt, "1f");
GPU.setUniformForProgram("advect", "u_velocity", 0, "1i");
GPU.setUniformForProgram("advect", "u_material", 1, "1i");
+ GPU.createProgram("diffuse", "2d-vertex-shader", "diffuseShader");
+ GPU.setUniformForProgram("diffuse" ,"u_textureSize", [width, height], "2f");
+ var alpha = dx*dx/(nu*dt);
+ GPU.setUniformForProgram("diffuse", "u_alpha", alpha, "1f");
+ GPU.setUniformForProgram("diffuse", "u_reciprocalBeta", 1/(4+alpha), "1f");
+ GPU.setUniformForProgram("diffuse", "u_material", 0, "1i");
+
GPU.createProgram("render", "2d-vertex-shader", "2d-render-shader");
GPU.setUniformForProgram("render" ,"u_textureSize", [width, height], "2f");
GPU.setUniformForProgram("render", "u_material", 0, "1i");
@@ -70,12 +81,18 @@ function render(){
// p = computePressure(u);
// u = subtractPressureGradient(u, p);
- GPU.step("advect", ["velocity", "velocity"], "advectedVelocity");//advect velocity
- GPU.swapTextures("velocity", "advectedVelocity");
+ GPU.step("advect", ["velocity", "velocity"], "nextVelocity");//advect velocity
+ GPU.swapTextures("velocity", "nextVelocity");
+ for (var i=0;i<10;i++){
+ GPU.step("diffuse", ["velocity"], "nextVelocity");//diffuse velocity
+ GPU.step("diffuse", ["nextVelocity"], "velocity");//diffuse velocity
+ }
+
- GPU.step("advect", ["velocity", "material"], "advectedMaterial");
- GPU.step("render", ["advectedMaterial"]);
- GPU.swapTextures("advectedMaterial", "material");
+ // GPU.step("diffuse", ["material"], "nextMaterial");
+ GPU.step("advect", ["velocity", "material"], "nextMaterial");
+ GPU.step("render", ["nextMaterial"]);
+ GPU.swapTextures("nextMaterial", "material");
} else resetWindow();
@@ -110,8 +127,8 @@ function resetWindow(){
}
}
GPU.initTextureFromData("velocity", width, height, "FLOAT", velocity, true);
- GPU.initTextureFromData("advectedVelocity", width, height, "FLOAT", new Float32Array(width*height*4), true);
- GPU.initFrameBufferForTexture("advectedVelocity");
+ GPU.initTextureFromData("nextVelocity", width, height, "FLOAT", new Float32Array(width*height*4), true);
+ GPU.initFrameBufferForTexture("nextVelocity");
var material = new Float32Array(width*height*4);
for (var i=0;i<height;i++){
for (var j=0;j<width;j++){
@@ -121,8 +138,8 @@ function resetWindow(){
}
GPU.initTextureFromData("material", width, height, "FLOAT", material, true);
GPU.initFrameBufferForTexture("material");
- GPU.initTextureFromData("advectedMaterial", width, height, "FLOAT", new Float32Array(width*height*4), true);
- GPU.initFrameBufferForTexture("advectedMaterial");
+ GPU.initTextureFromData("nextMaterial", width, height, "FLOAT", new Float32Array(width*height*4), true);
+ GPU.initFrameBufferForTexture("nextMaterial");
paused = false;
}
--
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