Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 1 Chapter 2 2D Graphics: Basics

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 2 Objectives F To understand the architecture and operations of a 2D graphics system F To understand 2D coordinate systems and equations of graphs F To be able to identify the various coordinate spaces in a rendering pipeline F To understand Java 2D program structure and the Graphics2D object F To graph equations with Java programs F To use basic 2D geometric primitives F To construct custom shapes using GeneralPath class F To construct geometric shapes through constructive area geometry

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 3 Rendering Pipeline 1.Construct the 2D objects. 2.Apply transformations to the objects. 3.Apply color and other rendering properties. 4.Render the scene on a graphics device.

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 4 2D Coordinate System

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 5 Line

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 6 Ellipse

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 7 Parametric Equation Parametric equation of an ellipse

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 8 Java 2D Coordinate System y-axis pointing downward

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 9 The Graphics2D Class F Java 2D rendering engine F Extends the Graphics class F Encapsulates all rendering functions void paintComponent(Graphics g){ } Graphics getGraphics()

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 10 Methods of Graphics Class void setColor(Color c) void setFont(Font f) void setXORMode(Color c) void setPaintMode() void translate(int x, int y) void drawLine(int x1, int y1, int x2, int y2) void drawRect(int x1, int y1, int width, int height) void drawOval(int x1, int y1, int width, int height) void drawArc(int x1, int y1, int width, int height, int start, int arc) void drawRoundRect(int x1, int y1, int width, int height, int arcW, int arcH) void drawPolygon(int[] xPoints, int[] yPoints, int nPoints) void fillRect(int x1, int y1, int width, int height) void fillOval(int x1, int y1, int width, int height) void fillArc(int x1, int y1, int width, int height, int start, int arc) void fillRoundRect(int x1, int y1, int width, int height, int arcW, int arcH) void fillPolygon(int[] xPoints, int[] yPoints, int nPoints) void drawString(String str, int x, int y)

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 11 Methods of Graphics2D Class void draw(Shape s) void fill(Shape s) void setTransform(AffineTransform Tx) void transform(AffineTransform Tx) void setPaint(Paint p) void setStroke(Stroke s) void clip(Shape s) void setComposite(Composite c) void addRenderingHints(Map hints)

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 12 A Simple Java 2D Program SourceRun public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D)g; g2.setColor(Color.blue); Ellipse2D e = new Ellipse2D.Double(-100, -50, 200, 100); AffineTransform tr = new AffineTransform(); tr.rotate(Math.PI / 6.0); Shape shape = tr.createTransformedShape(e); g2.translate(300,200); g2.scale(2,2); g2.draw(shape); g2.drawString("Hello 2D", 0, 0); }

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 13 Graphing a Spirograph Source The parametric equation Run

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 14 The Shape Interface

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 15 Draw Shapes F Line F Rectangle F Round rectangle F Ellipse F Arc F Quadratic curve F Cubic curve F Polygon Source Run

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 16 Constructive Area Geometry F Set-theoretic operations –Intersect –Add –Subtract –Exclusive or Source Run

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 17 GeneralPath F Five segment types –SEG_MOVETO –SEG_LINETO –SEG_QUADTO –SEG_CUBICTO –SEG_CLOSE F GeneralPath methods –moveTo –lineTo –quadTo –curveTo –closePath

Zhang & Liang, Computer Graphics Using Java 2D and 3D (c) 2007 Pearson Education, Inc. All rights reserved. 18 Winding Rules F To determine interior regions F Crossing number F Even-odd rule F Non-zero rule Source Run