Pro Question: get ALL in-between points from beginShape curveVertex() endShape

Chrisir · September 9, 2022, 4:18pm

Hello all!

as we all know, we can use
beginShape curveVertex() endShape to make long complex curves.

But it’s pretty much a black box.

How can I receive ALL points that are shown by curveVertex?

Apparently similar to curvePoint (with t / amt) but alas not quite

For a mcve see Easing equations with 'Influence' and 'In-/Outgoing Velocity' like in Adobe After Effects - #2 by Chrisir

Thank you all!

Chrisir

mnse · September 10, 2022, 9:28am

Hi @Chrisir,

Not that easy as each implementation JAVA2D, P2D,etc handles it different. There is a native catmul-rom implementation in PGraphics which would store the vertices as float array, but it doesn’t seems to be used at all…
for OpenGL related (P2D/P3D) ones there is an internal class InGeometry used to store the vertices which are not accessable and for JAVA2D it uses the awt.geom stuff.
Here is a quick and evil hack for the latter…

Cheers
— mnse

import java.lang.reflect.*;
import java.awt.geom.*;

ArrayList<PVector> points = null;

void setup() {
  size(300, 300);
}

void draw() {
  background(0);
  stroke(255);
  noFill();
  beginShape();
  for (int x = 0; x < width; x+=width/8) {
    curveVertex(x, x%2==0 ? height*0.25:height*0.75);
  }
  endShape();

  if (points == null)
    points = getVertices();

  PVector current = points.get(int(millis()/100) % points.size());
  noStroke();
  fill(255, 0, 0);  
  ellipse(current.x, current.y, 8, 8);
}

Class findClass(Class c, String search) {
  if (c.getName().endsWith(search))
    return c;
  else if (c.getSuperclass() != null)
    return findClass(c.getSuperclass(), search);
  return null;
}

ArrayList<PVector> getVertices() {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  try {
    GeneralPath gpath = null;
    Class pgclass = findClass(g.getClass(), "PGraphicsJava2D");
    if (pgclass == null) {
      throw new Exception("PGraphicsJava2D class not found");
    }
    Field[] fields = pgclass.getDeclaredFields();
    for (Field f : fields) {
      if ("gpath".equals(f.getName())) {      
        f.setAccessible(true);
        gpath = (GeneralPath) f.get(g);
      }
    }

    if (gpath == null) {
      throw new Exception("class member gpath not found");
    }

    PathIterator i = gpath.getPathIterator(null, 1);
    while (!i.isDone()) {
      double[] coords = new double[6];
      int segType = i.currentSegment(coords);
      if (segType != PathIterator.SEG_CLOSE) {
        list.add(new PVector((float)coords[0], (float)coords[1]));
      }
      i.next();
    }
  } 
  catch(Exception e) {
    println("Error: " + e);
  }
  return list;
}

video

glv · September 10, 2022, 1:10pm

Hello @mnse,

Please provide some context to above with links to the source in GitHub.

I took a quick look already but you have done the groundwork and others would benefit from that journey.

:)

mnse · September 12, 2022, 6:08am

Hi,

Git-References:

PGraphics
curveVertex() and curveVertexSegment which not seems to be used.
PGraphicsJava2D
gpath variable which the curve data is stored for Java2D mode.
curveVertexSegment which adds the curve data by using awt.geom methods

Additional info:

Cheers
— mnse

mnse · September 12, 2022, 2:04pm

Hi,

Just to add a way for P2D mode …

Cheers
— mnse

PS: For demonstration purposes only … so still quick hack without following good coding conventions.

import java.lang.reflect.*;
import java.awt.geom.*;

ArrayList<PVector> points = null;

void setup() {
  size(300, 300, P2D);
}

void draw() {
  background(0);
  stroke(255);
  noFill();
  beginShape();
  for (int x = 0; x < width; x+=width/8) {
    curveVertex(x, x%2==0 ? height*0.25:height*0.75);
  }
  endShape();

  if (points == null) {
    try {
      points = getPoints();
      if (points.isEmpty())
        throw new Exception("no data found !?");
    } 
    catch(Exception e) {
      println("Error: " + e);
      exit();
      return;
    }
  }

  PVector current = points.get(int(frameCount/5.) % points.size());
  noStroke();
  fill(255, 0, 0);  
  ellipse(current.x, current.y, 8, 8);
}

Class findClass(Class c, String search) {
  if (c.getName().endsWith(search))
    return c;
  else if (c.getSuperclass() != null)
    return findClass(c.getSuperclass(), search);
  return null;
}

ArrayList<PVector> getPoints() throws Exception {
  if (sketchRenderer().endsWith("PGraphics2D")) {
    return getVerticesP2D();
  } else if (sketchRenderer().endsWith("PGraphicsJava2D")) {
    return getVerticesJAVA2D();
  } else {
    throw new Exception("unsupported renderer " + sketchRenderer() + "  !?");
  }
}

// JAVA2D Mode
ArrayList<PVector> getVerticesJAVA2D() throws Exception {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  GeneralPath gpath = null;
  Class pgclass = findClass(g.getClass(), "PGraphicsJava2D");
  if (pgclass == null) {
    throw new Exception("PGraphicsJava2D class not found");
  }
  Field[] fields = pgclass.getDeclaredFields();
  for (Field f : fields) {
    if ("gpath".equals(f.getName())) {      
      f.setAccessible(true);
      gpath = (GeneralPath) f.get(g);
      break;
    }
  }

  if (gpath == null) {
    throw new Exception("class member gpath not found");
  }

  PathIterator i = gpath.getPathIterator(null, 1);
  while (!i.isDone()) {
    double[] coords = new double[6];
    int segType = i.currentSegment(coords);
    if (segType != PathIterator.SEG_CLOSE) {
      list.add(new PVector((float)coords[0], (float)coords[1]));
    }
    i.next();
  }
  return list;
}

// P2D Mode
ArrayList<PVector> getVerticesP2D() throws Exception {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  float[] vertices = {};
  int vertexCount  = 0;
  Class pgclass = findClass(g.getClass(), "PGraphicsOpenGL");
  if (pgclass == null) {
    throw new Exception("PGraphicsOpenGL class not found");
  }
  for (Field pgField : pgclass.getDeclaredFields()) {
    if ("tessellator".equals(pgField.getName())) {      
      pgField.setAccessible(true);        
      Object tessellatorObj = pgField.get(g);               
      for (Field tessellatorField : tessellatorObj.getClass().getDeclaredFields()) {
        if ("pathVertexCount".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertexCount = (int) tessellatorField.get(tessellatorObj);
        }          
        else if ("pathVertices".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertices = (float[]) tessellatorField.get(tessellatorObj);
        }
      }
    }
  }
  if (vertexCount == 0) {
    throw new Exception("no Vertices found");
  }    
  for (int i = 0; i < vertexCount*3; i+=3) {
    list.add(new PVector(vertices[i], vertices[i+1]));
  }
  return list;
}

video2

Github refs:

mnse · September 12, 2022, 3:35pm

Hi,

finally, to be somehow complete, add version for P3D. Nearly the same as P2D just convert the 2D to 3D coords.

Cheers
— mnse

import java.lang.reflect.*;
import java.awt.geom.*;

ArrayList<PVector> points = null;

void setup() {
  size(300, 300, P3D);
}

void draw() {  
  background(0);
  stroke(255);
  noFill();
  beginShape();
  for (int x = 0; x < width; x+=width/8) {
    if (g.is3D())
      curveVertex(x, x%2==0 ? height*0.25:height*0.75,x*-3.);
    else
      curveVertex(x, x%2==0 ? height*0.25:height*0.75);
  }
  endShape();

  if (points == null) {
    try {
      points = getPoints();
      if (points.isEmpty())
        throw new Exception("no data found !?");
    } 
    catch(Exception e) {
      println("Error: " + e);
      exit();
      return;
    }
  }

  PVector current = points.get(int(frameCount/5.) % points.size());
  noStroke();
  fill(255, 0, 0);
  if (g.is3D())
    translate(current.x,current.y,current.z);
  else
    translate(current.x,current.y);

  ellipse(0,0,5,5);    
}

Class findClass(Class c, String search) {
  if (c.getName().endsWith(search))
    return c;
  else if (c.getSuperclass() != null)
    return findClass(c.getSuperclass(), search);
  return null;
}

ArrayList<PVector> getPoints() throws Exception {
  if (sketchRenderer().equals(P2D)) {
    return getVerticesP2D();
  } else if (sketchRenderer().equals(P3D)) {
    return getVerticesP3D();
  } else if (sketchRenderer().equals(JAVA2D)) {
    return getVerticesJAVA2D();
  } else {
    throw new Exception("unsupported renderer " + sketchRenderer() + "  !?");
  }
}

// JAVA2D Mode
ArrayList<PVector> getVerticesJAVA2D() throws Exception {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  GeneralPath gpath = null;
  Class pgclass = findClass(g.getClass(), "PGraphicsJava2D");
  if (pgclass == null) {
    throw new Exception("PGraphicsJava2D class not found");
  }
  Field[] fields = pgclass.getDeclaredFields();
  for (Field f : fields) {
    if ("gpath".equals(f.getName())) {      
      f.setAccessible(true);
      gpath = (GeneralPath) f.get(g);
      break;
    }
  }

  if (gpath == null) {
    throw new Exception("class member gpath not found");
  }

  PathIterator i = gpath.getPathIterator(null, 1);
  while (!i.isDone()) {
    double[] coords = new double[6];
    int segType = i.currentSegment(coords);
    if (segType != PathIterator.SEG_CLOSE) {
      list.add(new PVector((float)coords[0], (float)coords[1], 0));
    }
    i.next();
  }
  return list;
}

// P2D Mode
ArrayList<PVector> getVerticesP2D() throws Exception {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  float[] vertices = {};
  int vertexCount  = 0;
  Class pgclass = findClass(g.getClass(), "PGraphicsOpenGL");
  if (pgclass == null) {
    throw new Exception("PGraphicsOpenGL class not found");
  }
  for (Field pgField : pgclass.getDeclaredFields()) {
    if ("tessellator".equals(pgField.getName())) {      
      pgField.setAccessible(true);        
      Object tessellatorObj = pgField.get(g);               
      for (Field tessellatorField : tessellatorObj.getClass().getDeclaredFields()) {
        if ("pathVertexCount".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertexCount = (int) tessellatorField.get(tessellatorObj);
        }          
        if ("pathVertices".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertices = (float[]) tessellatorField.get(tessellatorObj);
        }
      }
    }
  }
  if (vertexCount == 0) {
    throw new Exception("no Vertices found");
  }    
  for (int i = 0; i < vertexCount*3; i+=3) {
    list.add(new PVector(vertices[i], vertices[i+1],0));
  }
  return list;
}

// P3D Mode
ArrayList<PVector> getVerticesP3D() throws Exception {
  ArrayList<PVector> list = new ArrayList<PVector>(); 
  float[] vertices = {};
  int vertexCount  = 0;
  Class pgclass = findClass(g.getClass(), "PGraphicsOpenGL");
  if (pgclass == null) {
    throw new Exception("PGraphicsOpenGL class not found");
  }
  for (Field pgField : pgclass.getDeclaredFields()) {
    if ("tessellator".equals(pgField.getName())) {      
      pgField.setAccessible(true);        
      Object tessellatorObj = pgField.get(g);               
      for (Field tessellatorField : tessellatorObj.getClass().getDeclaredFields()) {
        if ("pathVertexCount".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertexCount = (int) tessellatorField.get(tessellatorObj);
        }          
        if ("pathVertices".equals(tessellatorField.getName())) {      
          tessellatorField.setAccessible(true);        
          vertices = (float[]) tessellatorField.get(tessellatorObj);
        }
      }
    }
  }
  if (vertexCount == 0) {
    throw new Exception("no Vertices found");
  }    
  for (int i = 0; i < vertexCount*3; i+=3) {
    PVector m = new PVector(modelX(vertices[i],vertices[i+1],vertices[i+2])
                           ,modelY(vertices[i],vertices[i+1],vertices[i+2])
                           ,modelZ(vertices[i],vertices[i+1],vertices[i+2]));   
    list.add(new PVector(screenX(m.x,m.y,m.z)
                        ,screenY(m.x,m.y,m.z)
                        ,screenZ(m.x,m.y,m.z)));
  }
  return list;
}

video3

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Pro Question: get ALL in-between points from beginShape curveVertex() endShape

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