Triangle Draw Method

Question

I have trouble drawing a triangle with the draw(Graphics g) method in Java. I can draw a rectangle like so:

public void draw(Graphics g) {
    g.setColor(colorFill);
    g.fillRect(p.x, p.y, width, height);
    g.setColor(colorBorder);
    g.drawRect(p.x, p.y, width, height);
    drawHandles(g);

Where p represents "the top left corner of the shapes". How would I draw the triangle in the same manner?

Could someone give me an example for a standard triangle?

Answer 1

There is not a drawTriangle method neither in Graphics nor Graphics2D. You need to do it by yourself. You can draw three lines using the drawLine method or use one these methods:

• drawPolygon(int[] xPoints, int[] yPoints, int nPoints)
• drawPolygon(Polygon p)
• drawPolyline(int[] xPoints, int[] yPoints, int nPoints)

These methods work with polygons. You may change the prefix draw to fill when you want to fill the polygon defined by the point set. I inserted the documentation links. Take a look to learn how to use them.

There is the GeneralPath class too. It can be used with Graphics2D, which is capable to draw Shapes. Take a look:

• http://docs.oracle.com/javase/tutorial/2d/geometry/arbitrary.html

Answer 2

You should try using the Shapes API.

Take a look at JPanel repaint from another class which is all about drawing triangles, look to the getPath method for some ideas

You should also read up on GeneralPath & Drawing Arbitrary Shapes.

This method is much easy to apply AffineTransformations to

Answer 3

Drawing triangle is not provided with standard Java library. I saw sample code here :

http://www.dreamincode.net/forums/topic/52352-draw-line-triangle/

Answer 4

Use a line algorithm to connect point A with point C, and in an outer loop, let point A wander towards point B with the same line algorithm and with the wandering coordinates, repeat drawing that line. You can probably also include a z delta with which is also incremented iteratively. For the line algorithm, just calculate two or three slopes for the delta change of each coordinate and set one slope to 1 after changing the two others proportionally so they are below 1. This is very important for drawing closed geometrical areas between connected mesh particles. Take a look at the Qt Elastic Nodes example and now imagine drawing triangles between the nodes after stretching this over a skeleton. As long as it will remain online

Answer 5

there is no command directly to draw Triangle. For Drawing of triangle we have to use the concept of lines here.

i.e, g.drawLines(Coordinates of points)

Answer 6

There is no direct method to draw a triangle. You can use drawPolygon() method for this. It takes three parameters in the following form: drawPolygon(int x[],int y[], int number_of_points); To draw a triangle: (Specify the x coordinates in array x and y coordinates in array y and number of points which will be equal to the elements of both the arrays.Like in triangle you will have 3 x coordinates and 3 y coordinates which means you have 3 points in total.) Suppose you want to draw the triangle using the following points:(100,50),(70,100),(130,100) Do the following inside public void paint(Graphics g):

int x[]={100,70,130};
int y[]={50,100,100};
g.drawPolygon(x,y,3);

Similarly you can draw any shape using as many points as you want.

Answer 7

You can use Processing library: https://processing.org/reference/PGraphics.html

There is a method called triangle():

g.triangle(x1,y1,x2,y2,x3,y3)