java/examples/Topics/Simulate/Fluid/applet/Fluid.java

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+import processing.core.*; 
+
+import java.applet.*; 
+import java.awt.*; 
+import java.awt.image.*; 
+import java.awt.event.*; 
+import java.io.*; 
+import java.net.*; 
+import java.text.*; 
+import java.util.*; 
+import java.util.zip.*; 
+import java.util.regex.*; 
+
+public class Fluid extends PApplet {
+
+/**
+ * Fluid 
+ * by Glen Murphy. 
+ * 
+ * Click and drag the mouse to move the simulated fluid.
+ * Adjust the "res" variable below to change resolution.
+ * Code has not been optimised, and will run fairly slowly.
+ */
+ 
+int res = 2;
+int penSize = 30;
+int lwidth;
+int lheight;
+int pnum = 30000;
+vsquare[][] v;
+vbuffer[][] vbuf;
+particle[] p = new particle[pnum];
+int pcount = 0;
+int mouseXvel = 0;
+int mouseYvel = 0;
+
+public void setup() 
+{
+  size(200, 200);
+  noStroke();
+  frameRate(30);
+  lwidth = width/res;
+  lheight = height/res;
+  v = new vsquare[lwidth+1][lheight+1];
+  vbuf = new vbuffer[lwidth+1][lheight+1];
+  for (int i = 0; i < pnum; i++) {
+    p[i] = new particle(random(res,width-res),random(res,height-res));
+  }
+  for (int i = 0; i <= lwidth; i++) {
+    for (int u = 0; u <= lheight; u++) {
+      v[i][u] = new vsquare(i*res,u*res);
+      vbuf[i][u] = new vbuffer(i*res,u*res);
+    }
+  }
+}
+
+public void draw() 
+{
+  background(0xff666666);
+  
+  int axvel = mouseX-pmouseX;
+  int ayvel = mouseY-pmouseY;
+
+  mouseXvel = (axvel != mouseXvel) ? axvel : 0;
+  mouseYvel = (ayvel != mouseYvel) ? ayvel : 0;
+
+  for (int i = 0; i < lwidth; i++) {
+    for (int u = 0; u < lheight; u++) {
+      vbuf[i][u].updatebuf(i,u);
+      v[i][u].col = 32;
+    }
+  }
+  for (int i = 0; i < pnum-1; i++) {
+    p[i].updatepos();
+  }
+  for (int i = 0; i < lwidth; i++) {
+    for (int u = 0; u < lheight; u++) {
+      v[i][u].addbuffer(i, u);
+      v[i][u].updatevels(mouseXvel, mouseYvel);
+      v[i][u].display(i, u);
+    }
+  }
+}
+
+class particle {
+  float x;
+  float y;
+  float xvel;
+  float yvel;
+  int pos;
+  particle(float xIn, float yIn) {
+    x = xIn;
+    y = yIn;
+  }
+
+  public void updatepos() {
+    float col1;
+    if (x > 0 && x < width && y > 0 && y < height) {
+      int vi = (int)(x/res);
+      int vu = (int)(y/res);
+      vsquare o = v[vi][vu];    
+      
+      float ax = (x%res)/res;
+      float ay = (y%res)/res;
+      
+      xvel += (1-ax)*v[vi][vu].xvel*0.05f;
+      yvel += (1-ay)*v[vi][vu].yvel*0.05f;
+      
+      xvel += ax*v[vi+1][vu].xvel*0.05f;
+      yvel += ax*v[vi+1][vu].yvel*0.05f;
+      
+      xvel += ay*v[vi][vu+1].xvel*0.05f;
+      yvel += ay*v[vi][vu+1].yvel*0.05f;
+
+      o.col += 4;
+      
+      x += xvel;
+      y += yvel;
+    }
+    else {
+      x = random(0,width);
+      y = random(0,height);
+      xvel = 0;
+      yvel = 0;
+    }
+
+    xvel *= 0.5f;
+    yvel *= 0.5f;
+  }
+}
+
+class vbuffer {
+  int x;
+  int y;
+  float xvel;
+  float yvel;
+  float pressurex = 0;
+  float pressurey = 0;
+  float pressure = 0;
+
+  vbuffer(int xIn,int yIn) {
+    x = xIn;
+    y = yIn;
+    pressurex = 0;
+    pressurey = 0;
+    }
+
+  public void updatebuf(int i, int u) {
+    if (i>0 && i<lwidth && u>0 && u<lheight) {
+      pressurex = (v[i-1][u-1].xvel*0.5f + v[i-1][u].xvel + v[i-1][u+1].xvel*0.5f - v[i+1][u-1].xvel*0.5f - v[i+1][u].xvel - v[i+1][u+1].xvel*0.5f);
+      pressurey = (v[i-1][u-1].yvel*0.5f + v[i][u-1].yvel + v[i+1][u-1].yvel*0.5f - v[i-1][u+1].yvel*0.5f - v[i][u+1].yvel - v[i+1][u+1].yvel*0.5f);
+      pressure = (pressurex + pressurey)*0.25f;
+      }
+    }
+  }
+
+class vsquare {
+  int x;
+  int y;
+  float xvel;
+  float yvel;
+  float col;
+
+  vsquare(int xIn,int yIn) {
+    x = xIn;
+    y = yIn;
+    }
+
+  public void addbuffer(int i, int u) {
+    if (i>0 && i<lwidth && u>0 && u<lheight) {
+      xvel += (vbuf[i-1][u-1].pressure*0.5f
+              +vbuf[i-1][u].pressure
+              +vbuf[i-1][u+1].pressure*0.5f
+              -vbuf[i+1][u-1].pressure*0.5f
+              -vbuf[i+1][u].pressure
+              -vbuf[i+1][u+1].pressure*0.5f
+              )*0.25f;
+      yvel += (vbuf[i-1][u-1].pressure*0.5f
+              +vbuf[i][u-1].pressure
+              +vbuf[i+1][u-1].pressure*0.5f
+              -vbuf[i-1][u+1].pressure*0.5f
+              -vbuf[i][u+1].pressure
+              -vbuf[i+1][u+1].pressure*0.5f
+              )*0.25f;
+      }
+    }
+
+  public void updatevels(int mvelX, int mvelY) {
+    if (mousePressed) {
+      float adj = x - mouseX;
+      float opp = y - mouseY;
+      float dist = sqrt(opp*opp + adj*adj);
+      if (dist < penSize) {
+        if (dist < 4) dist = penSize;
+        float mod = penSize/dist;
+        xvel += mvelX*mod;
+        yvel += mvelY*mod;
+        }
+      }
+
+    xvel *= 0.99f;
+    yvel *= 0.99f;
+  }
+  
+  public void display(int i, int u) {
+    float tcol = 0;
+    if (col > 255) col = 255;
+    if (i>0 && i<lwidth-1 && u>0 && u<lheight-1) {
+      tcol = (+ v[i][u+1].col 
+              + v[i+1][u].col 
+              + v[i+1][u+1].col*0.5f
+              )*0.4f;
+      tcol = (int)(tcol+col*0.5f);
+      }
+    else {
+      tcol = (int)col;
+      }
+    fill(tcol, tcol, tcol);
+    rect(x,y,res,res);
+  }
+}
+
+
+
+  static public void main(String args[]) {
+    PApplet.main(new String[] { "Fluid" });
+  }
+}