Drawing a sine curve in 3D

I would like to draw a sine curve in Java 3D. Is there a way to do that? I am generating points on the fly and putting them in Point3D array. Then I generated the indices and used IndexedLineArray to draw lines on the fly. But they don't show up properly and there is no consistency. Is it because Java 3D is multi-threaded?
Is there a better way to do it? I need some advice. If necessary, I will post some code also.
Thank you,
-Sri :)

Yes, I have set the appearance, but I am not using any color values.
Here's some sample code:
==========================
private IndexedLineArray la;
private Shape3D shape;
Appearance a = new Appearance();
PolygonAttributes attr = new PolygonAttributes();
attr.setCullFace(PolygonAttributes.CULL_NONE);
a.setPolygonAttributes(attr);
shape = new Shape3D(la,a);
shape.setCapability(Shape3D.ALLOW_GEOMETRY_WRITE);
===========================
I think the points are being drawn too fast. Maybe I should reduce the number of frames?
-Sri :)

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RealDave wrote:
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You call it four times...
Here is a snippet that explains the math...
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PLEASE HELP!! Drawing Lines

Hi, I'm new to Java and i need some help with drawing an asymptotic curve.
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http://www.iit.edu/~smart/acadyear/fredstof.gif_
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http://forum.java.sun.com/thread.jspa?threadID=5258979

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function(){return A.apply(null,[this].concat($A(arguments)))}
Not being able to, at a minimum, draw an arc or circle by radius is absurd and there can be no debate on this.
Well, here's the debate that "cannot be":
This ideal arc tool you envision; tell me, which radius would you expect it to prompt you for when you need to draw a non-circular arc?
Do you think that just because a software asks you to specify a circle in terms of center coordinates and radius that what it renders is therefore actually a circle, when otherwise it is not? Again, that's nonsense.
In about 30 minutes, I could create for you a Javascript-based tool that runs in Illustrator and that prompts you for center coordinates and a radius and then draws a circle. Would you then consider the circles it draws to be more "correct" or "accurate"? In fact, for my own purposes, I have a very simple Javascript that lets me define an ellipse in terms of diameter and "angle" (tilt relative to the picture plane), just as ellipses are defined on industry-standard drafting templates.
Similarly, a plug-in programmer could code an actual real-time interactive tool with which you would mousedown where you want the center of a circle to be, and then drag so as to define the radius. The interface of such a tool could even require you to drag the end of the displayed "radius" in order to change the size of the circle, and display no Bezier control points unless "converted" from a "circle" to a Bezier path. Wanna see one? Canvas. But do you think it doesn't actually draw a Bezier curve?
Regardless, if either those tools exist in Illustrator (and just about any other program of the same type and purpose) the actual math defining the resulting path would still be cubic Bezier equations, whether you ever saw path handles and height/width values or not. If that bothers you, and you actually think it matters, you just have to use something else. And good luck efficiently doing general-purpose commercial illustration with a CAD program. Bezier math is the curve-rendering math basis of PostScript, and therefore of Illustrator. It is not "sub-standard" or "inferior" to other curve rendering equations. In fact, it is arguably superior.
Again, if all you're saying is that Illusrtrator's Ellipse interface is sub-standard, I'd be the last to disagree. FreeHand's Elipse tool, for example, allows you to define any circular or eliptical arc or circle or ellipse with the one tool. But that doesn't change the fact that the actual math being used to plot the curve is still the same cubic Bezier equation as used in Illustrator. And you seem to think that a Bezier-described arc is not a "real" arc to any extent that matters one whit to anything.
We've had this discussion here before. No software on the planet actually "draws a circle." Strictly speaking, you've never even seen an "actual" circle. The only "circle" (or triangle, or any other geometric primitive) you've ever actually seen is a mere physical approximation of an ideal concept. The physical result of all curve-drawing algorithms is a mere approximation, limited by the physical realities of the rendering mechanism. So if you are going to persist in this utter nonsense of making the most extremely huge mountain out of a literally microscopic molehill, you are eventually going to have to speak to the actual degree of inaccuracy that causes you such angst.
Give me an example of a software that you think draws a "real" circle. A CAD program? How does that work? Do you know? Do you think it actually starts by shining the emitter of a CRT at the point on the screen you specify as the center, moves horizontally the distance you specify as the radius, and then scribes a circular path around the center as if being swung on a string? If that "circle" is exported as a DXF file and is then used to drive to an NC plotter, do you think the path in the DXF file is actually a circle, and not a series of straight-path facets that merely approximate a circle?
When that DXF drawing is plotted to a pen plotter, do you think the instructions to the plotter actually say "spin the pen around this point at this distance"? No, it says "step the roller motor at these increments (move Y), while stepping the pen holder at these increments (move X)." In fact, it really usually says, "go to this XY coordinate. Then go to this XY coordinate. Then go to this XY coordinate....", in other words, drawing straight-line facets. Does that sound more like "radius and center" or " X and Y" to you?
So do you consider a set of XY coordinate pairs that merely describe the corners of a multi-sided polygon to be a "truer" circle than that generated by automatically plotting a curve at the highest physical resolution of a marking device according to the resolution independent nature of a cubic Bezier equation?
Have you ever run a CAD program in which you had to "regenerate the buffer" (i.e.; re-rasterize the screen image) after zooming in on the path that you naively think is being described as an "actual" circle? Have you never zoomed into a 3D model in an interactive video game and seen painfully ugly faceting?
Now, an NC device (say, a cylinder boring machine) may actually receive commands to "set the cutter arm to this distance, then begin spinning the spindle motor at this RPM while tracking the depth at this rate." But I wouldn't recommend using that NC device or its instructions to render curves to your computer monitor or to a printing press. But if all you want to do is draw circles with a boring bar....
JET

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{ 1.5, 0.25, 1.0 }, { 3.5, 1.25, 1.0 }, { 0.75, 1.75, 1.0 },
{ 0.75, 5.0, 1.0 }, { 7.5, 7.5, 2.0 }, { 7.7, 1.0, 1.0 },
{ 4.3, 2.2, 1.0 }, { 5.1, 0.75, 1.0 }, { 7.5, 0.5, 1.0 }
knots = new double[] {
// u_0 u_1 u_2 u_3 u_4 u_5 u_6 u_7 u_8
0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 1/3.0, 2/3.0,
// u_9 u_10 u_11 u_12 u_13 u_14 u_15
1.0, 1.0, 1.0, 1.0, 1.0, 1.0, 1.0
public void setCircleOne() // circle in triangle
points = new double[][] {
{ 4.0, 1.0, 1.0 }, { 0.5, 1.0, 0.5 }, { 2.25, 4.03, 1.0 },
{ 4.0, 7.06, 0.5 }, { 5.75, 4.03, 1.0 }, { 7.5, 1.0, 0.5 },
{ 4.0, 1.0, 1.0 }
knots = new double[] {
// u_0 u_1 u_2 u_3 u_4 u_5 u_6 u_7 u_8 u_9
0.0, 0.0, 0.0, 1/3.0, 1/3.0, 2/3.0, 2/3.0, 1.0, 1.0, 1.0
public void setCircleTwo() // circle in square
double w = Math.pow(2, 0.5)/2;
points = new double[][] {
{ 4.0, 1.0, 1.0 }, { 1.0, 1.0, w }, { 1.0, 4.0, 1.0 },
{ 1.0, 7.0, w }, { 4.0, 7.0, 1.0 }, { 7.0, 7.0, w },
{ 7.0, 4.0, 1.0 }, { 7.0, 1.0, w }, { 4.0, 1.0, 1.0 }
knots = new double[] {
// u_0 u_1 u_2 u_3 u_4 u_5 u_6 u_7 u_8 u_9 u_10 u_11
0.0, 0.0, 0.0, 1/4.0, 1/4.0, 1/2.0, 1/2.0, 3/4.0, 3/4.0, 1.0, 1.0, 1.0
private void drawConvexPolyline(Graphics2D g2)
g2.setPaint(new Color(240,180,180));
double lastX = 0, lastY = 0;
Point2D.Double pv;
for(int j = 0; j < points.length; j++)
pv = modelToView(points[j][0], points[j][1]);
if(j > 0)
g2.draw(new Line2D.Double(pv.x, pv.y, lastX, lastY));
lastX = pv.x;
lastY = pv.y;
private void drawKnots(Graphics2D g2)
g2.setPaint(Color.blue);
// show knots only if there are curve segments, ie, only if p > m-p
if(p > m-p)
return;
// curve domain is [u[p], u[m-p]]
// send all knots within the domain, ie, including endpoints
// with care to adjust knot interval for last knot to the previous
// interval, viz, m-p-1 to avoid ArrayIndexOutOfBoundsException
// in N[k] in getBasisValues method, ie, ensure N[k <= n]
// in other words, this loop counts valid curve segments plus
// one for the last knot on the last curve segment
for(int j = p, k = p; j <= m-p; j++, k++)
if(j < m-p && knots[j+1] - knots[j] == 0)
continue;
if(j == m-p)
k = m-p-1;
Point2D.Double pv = getValue(knots[j], k);
GeneralPath path = new GeneralPath();
path.moveTo((float)pv.x-4, (float)pv.y);
path.lineTo((float)pv.x, (float)pv.y-4);
path.lineTo((float)pv.x+4, (float)pv.y);
path.lineTo((float)pv.x, (float)pv.y+4);
g2.fill(path);
private void drawPoints(Graphics2D g2)
g2.setPaint(Color.red);
for(int j = 0; j < points.length; j++)
Point2D.Double pv = modelToView(points[j][0], points[j][1]);
g2.fill(new Ellipse2D.Double(pv.x - 2, pv.y - 2, 4, 4));
public Point2D.Double modelToView(double x, double y)
double h = getHeight();
Point2D.Double pView = new Point2D.Double();
pView.x = PAD + x * (getWidth() - 2*PAD) / X_MAX;
pView.y = h - PAD - (y * (h - 2*PAD) / Y_MAX);
return pView;
private Point2D.Double viewToModel(double x, double y)
double w = getWidth();
double h = getHeight();
Point2D.Double pModel = new Point2D.Double();
pModel.x = (x - PAD) * X_MAX / (w - 2*PAD);
pModel.y = (h - PAD - y) * Y_MAX / (h - 2*PAD);
return pModel;
private void drawAxes(Graphics2D g2)
Font font = new Font("lucida sans", Font.PLAIN, 14);
g2.setFont(font);
FontRenderContext frc = g2.getFontRenderContext();
double w = getWidth();
double h = getHeight();
double xInc = (w - 2*PAD) / X_MAX;
double yInc = (h - 2*PAD) / Y_MAX;
double x1 = PAD, y1 = PAD, x2 = w-PAD, y2 = h-PAD;
g2.setPaint(new Color(200,220,220));
// grid lines - vertical lines across
for(int j = 0; j <= X_MAX; j++)
g2.draw(new Line2D.Double(x1, y1, x1, y2));
x1 += xInc;
// horizontal lines down
x1 = PAD;
for(int j = 0; j < Y_MAX; j++)
g2.draw(new Line2D.Double(x1, y1, x2, y1));
y1 += yInc;
g2.setPaint(Color.black);
// ordinate
g2.draw(new Line2D.Double(PAD, PAD, PAD, h-PAD));
// tic marks
x1 = PAD - TICK; y1 = PAD; x2 = PAD;
for(int j = 0; j <= Y_MAX; j++)
g2.draw(new Line2D.Double(x1, y1, x2, y1));
y1 += yInc;
// labels
for(int j = 0; j <= Y_MAX; j++)
String s = String.valueOf(Y_MAX - j);
float width = (float)font.getStringBounds(s,frc).getWidth();
float height = font.getLineMetrics(s, frc).getAscent();
float sx = PAD - TICK - MARGIN - width;
float sy = (float)(PAD + j * yInc + height/2);
g2.drawString(s, sx, sy);
// abcissa
g2.draw(new Line2D.Double(PAD, h-PAD, w-PAD, h-PAD));
// tic marks
x1 = PAD; y1 = h-PAD; y2 = h-PAD+TICK;
for(int j = 0; j <= X_MAX; j++)
g2.draw(new Line2D.Double(x1, y1, x1, y2));
x1 += xInc;
// labels
for(int j = 0; j <= X_MAX; j++)
String s = String.valueOf(j);
float width = (float)font.getStringBounds(s,frc).getWidth();
float height = font.getLineMetrics(s, frc).getAscent();
float sx = (float)(PAD + j * xInc - width/2);
float sy = (float)(h - PAD + TICK + MARGIN + height);
g2.drawString(s, sx, sy);
public void setPoint(int index, double x, double y)
Point2D.Double pModel = viewToModel(x, y);
points[index][0] = pModel.x;
points[index][1] = pModel.y;
firstTime = true;
repaint();
public void setKnot(int index, double value)
knots[index] = value;
firstTime = true;
repaint();
public void setWeight(int index, double weight)
points[index][2] = weight;
firstTime = true;
repaint();
class PointManager extends MouseInputAdapter
NURBSPanel nurbsPanel;
double[][] points;
Point2D.Double offset;
int selectedIndex;
boolean dragging;
public PointManager(NURBSPanel np)
nurbsPanel = np;
points = nurbsPanel.points;
offset = new Point2D.Double();
dragging = false;
public void mousePressed(MouseEvent e)
Point p = e.getPoint();
Point2D.Double pView;
for(int j = 0; j < points.length; j++)
pView = nurbsPanel.modelToView(points[j][0], points[j][1]);
if(p.distance(pView) < 5)
selectedIndex = j;
offset.x = p.x - pView.x;
offset.y = p.y - pView.y;
dragging = true;
break;
public void mouseReleased(MouseEvent e)
dragging = false;
public void mouseDragged(MouseEvent e)
if(dragging)
double x = e.getX() - offset.x;
double y = e.getY() - offset.y;
nurbsPanel.setPoint(selectedIndex, x, y);
class KnotDisplay extends JPanel
NURBSPanel nurbsPanel;
JTable table;
JSlider slider;
double scale;
boolean valueIsAdjusting;
int selectedIndex;
public KnotDisplay(NURBSPanel np)
nurbsPanel = np;
valueIsAdjusting = false;
selectedIndex = 4;
setBorder(BorderFactory.createTitledBorder("knots"));
setLayout(new BorderLayout());
add(getTable(), "North");
add(getSlider());
add(getRadioPanel(), "South");
private void moveKnot(double d)
nurbsPanel.setKnot(selectedIndex, d);
table.setValueAt(String.valueOf(d), 0, selectedIndex);
private void changeSelection()
// reset slider values
double lo = nurbsPanel.knots[selectedIndex-1];
double hi = nurbsPanel.knots[selectedIndex+1];
scale = Math.rint((hi - lo) * 1000);
int min = (int)(lo * scale);
int max = (int)(hi * scale);
boolean enabled = true;
if(max - min == 0)
enabled = false;
slider.setEnabled(enabled);
int value = (int)(nurbsPanel.knots[selectedIndex] * scale);
valueIsAdjusting = true;
slider.setMinimum(min);
slider.setMaximum(max);
slider.setValue(value);
valueIsAdjusting = false;
private JTable getTable()
String[] headers = new String[nurbsPanel.knots.length];
Object[][]data = new Object[1][nurbsPanel.knots.length];
for(int col = 0; col < data[0].length; col++)
headers[col] = "";
data[0][col] = String.valueOf(nurbsPanel.knots[col]);
table = new JTable(new DefaultTableModel(data, headers));
TableCellRenderer renderer = table.getDefaultRenderer(String.class);
((JLabel)renderer).setHorizontalAlignment(JLabel.CENTER);
table.setEnabled(false);
return table;
private JSlider getSlider()
double lo = nurbsPanel.knots[selectedIndex-1];
double hi = nurbsPanel.knots[selectedIndex+1];
scale = Math.rint((hi - lo) * 1000);
int min = (int)(lo * scale);
int max = (int)(hi * scale);
int value = (int)(nurbsPanel.knots[selectedIndex] * scale);
slider = new JSlider(JSlider.HORIZONTAL, min, max, value);
if(max - min == 0)
slider.setEnabled(false);
slider.addChangeListener(new ChangeListener()
public void stateChanged(ChangeEvent e)
if(!valueIsAdjusting)
double value = slider.getValue() / scale;
moveKnot(value);
return slider;
private JPanel getRadioPanel()
final JRadioButton[] buttons = new JRadioButton[nurbsPanel.knots.length];
ButtonGroup group = new ButtonGroup();
ActionListener l = new ActionListener()
public void actionPerformed(ActionEvent e)
JRadioButton radio = (JRadioButton)e.getSource();
int index = -1;
for(int j = 0; j < buttons.length; j++)
if(radio == buttons[j])
selectedIndex = j;
break;
changeSelection();
JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.weightx = 1.0;
for(int j = 0; j < nurbsPanel.knots.length; j++)
buttons[j] = new JRadioButton();
group.add(buttons[j]);
buttons[j].addActionListener(l);
panel.add(buttons[j], gbc);
buttons[0].setEnabled(false);
buttons[buttons.length-1].setEnabled(false);
buttons[selectedIndex].setSelected(true);
return panel;
class WeightsPanel extends JPanel
NURBSPanel nurbsPanel;
JTable table;
JSlider slider;
double scale;
boolean valueIsAdjusting;
int selectedIndex;
public WeightsPanel(NURBSPanel np)
nurbsPanel = np;
valueIsAdjusting = false;
selectedIndex = 2;
setBorder(BorderFactory.createTitledBorder("weights"));
setLayout(new BorderLayout());
add(getTable(), "North");
add(getSlider());
add(getRadioPanel(), "South");
private void changeWeight(double d)
nurbsPanel.setWeight(selectedIndex, d);
table.setValueAt(String.valueOf(d), 0, selectedIndex);
private void changeSelection()
// reset slider value
double weight = nurbsPanel.points[selectedIndex][2];
setScale(weight);
int value = (int)(weight * scale);
valueIsAdjusting = true;
slider.setValue(value);
valueIsAdjusting = false;
private void setScale(double weight)
if(weight < 1.0)
scale = slider.getMaximum()/5;
else
scale = 2.0;
private JTable getTable()
String[] headers = new String[nurbsPanel.points.length];
Object[][]data = new Object[1][nurbsPanel.points.length];
for(int col = 0; col < data[0].length; col++)
headers[col] = "";
data[0][col] = String.valueOf(nurbsPanel.points[col][2]);
table = new JTable(new DefaultTableModel(data, headers));
TableCellRenderer renderer = table.getDefaultRenderer(String.class);
((JLabel)renderer).setHorizontalAlignment(JLabel.CENTER);
table.setEnabled(false);
return table;
private JSlider getSlider()
double weight = nurbsPanel.points[selectedIndex][2];
setScale(weight);
int value = (int)(weight * scale);
slider = new JSlider(JSlider.HORIZONTAL, 0, 50, value);
slider.addChangeListener(new ChangeListener()
public void stateChanged(ChangeEvent e)
if(!valueIsAdjusting)
double value = slider.getValue() / scale;
changeWeight(value);
return slider;
private JPanel getRadioPanel()
final JRadioButton[] buttons = new JRadioButton[nurbsPanel.points.length];
ButtonGroup group = new ButtonGroup();
ActionListener l = new ActionListener()
public void actionPerformed(ActionEvent e)
JRadioButton radio = (JRadioButton)e.getSource();
int index = -1;
for(int j = 0; j < buttons.length; j++)
if(radio == buttons[j])
selectedIndex = j;
break;
changeSelection();
JPanel panel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.weightx = 1.0;
for(int j = 0; j < nurbsPanel.points.length; j++)
buttons[j] = new JRadioButton();
group.add(buttons[j]);
buttons[j].addActionListener(l);
panel.add(buttons[j], gbc);
buttons[selectedIndex].setSelected(true);
return panel;

Drawing a sine curve in 3D

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