在前面的章节中,我们学习了如何使用JOGL绘制线条,三角形,菱形等形状.我们通过将预定义字段 Gl_lines 传递给 glBegin()方法来绘制线条.
除了 GL_LINES , glBegin()方法接受另外八个参数.您可以使用它们绘制不同的形状.它们的使用方法与GL_LINES相同.
下表显示了 glBegin()方法参数及其描述 :
Sr.No | 参数和描述 |
---|---|
1 | GL_LINES 将每对顶点创建为独立的线段. |
2 | GL_LINE_STRIP 从第一个顶点到最后一个顶点绘制一组连接的线段. |
3 | GL_LINE_LOOP 从第一个顶点到最后一个顶点绘制一组连接的线段,再次返回到第一个顶点. |
4 | GL_TRIANGLES 将每个顶点的三元组视为独立的三角. |
5 | GL_TRIANGLE_STRIP 绘制一组连接的三角形.为前两个顶点后面的每个顶点定义一个三角形. |
6 | GL_TRIANGLE_FAN 绘制一组连接的三角形.为前两个顶点之后的每个顶点定义一个三角形. |
7 | GL_QUADS 将每组四个顶点视为一个独立的四边形. |
8 | GL_QUAD_STRIP 绘制一组连接的四边形.在第一对之后呈现的每对顶点都定义了一个四边形. |
9 | GL_POLYGON 绘制单个凸多边形.顶点1,...,n定义此多边形. |
让我们看一些使用的示例glBegin()参数.
import javax.media.opengl.GL2; import javax.media.opengl.GLAutoDrawable; import javax.media.opengl.GLCapabilities; import javax.media.opengl.GLEventListener; import javax.media.opengl.GLProfile; import javax.media.opengl.awt.GLCanvas; import javax.swing.JFrame; public class LineStrip implements GLEventListener { @Override public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin (GL2.GL_LINE_STRIP); gl.glVertex3f(-0.50f,-0.75f, 0); gl.glVertex3f(0.7f,0.5f, 0); gl.glVertex3f(0.70f,-0.70f, 0); gl.glVertex3f(0f,0.5f, 0); gl.glEnd(); } @Override public void dispose(GLAutoDrawable arg0) { //method body } @Override public void init(GLAutoDrawable arg0) { // method body } @Override public void reshape(GLAutoDrawable arg0, int arg1, int arg2, int arg3, int arg4) { // method body } public static void main(String[] args) { //getting the capabilities object of GL2 profile final GLProfile profile = GLProfile.get(GLProfile.GL2); GLCapabilities capabilities = new GLCapabilities(profile); // The canvas final GLCanvas glcanvas = new GLCanvas(capabilities); LineStrip r = new LineStrip(); glcanvas.addGLEventListener(r); glcanvas.setSize(400, 400); //creating frame final JFrame frame = new JFrame ("LineStrip"); //adding canvas to frame frame.getContentPane().add(glcanvas); frame.setSize(frame.getContentPane().getPreferredSize()); frame.setVisible(true); }//end of main }//end of classimport javax.media.opengl.GL2;
如果编译并执行上面的代码,则生成以下输出 :
public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin (GL2.GL_LINE_LOOP); gl.glVertex3f( -0.50f, -0.75f, 0); gl.glVertex3f(0.7f, .5f, 0); gl.glVertex3f(0.70f, -0.70f, 0); gl.glVertex3f(0f, 0.5f, 0); gl.glEnd(); }
如果用上面的代码替换任何基本模板程序的 display()方法,编译并执行它,生成以下输出 :
public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin(GL2.GL_TRIANGLES); // Drawing Using Triangles gl.glVertex3f(0.5f,0.7f,0.0f); // Top gl.glVertex3f(-0.2f,-0.50f,0.0f); // Bottom Left gl.glVertex3f(0.5f,-0.5f,0.0f); // Bottom Right gl.glEnd(); }
如果用上面的代码替换任何基本模板程序的 display()方法,编译并执行它,生成以下输出 :
public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin (GL2.GL_TRIANGLE_STRIP); gl.glVertex3f(0f,0.5f,0); gl.glVertex3f(-0.50f,-0.75f,0); gl.glVertex3f(0.28f,0.06f,0); gl.glVertex3f(0.7f,0.5f,0); gl.glVertex3f(0.7f,-0.7f,0); gl.glEnd(); }
如果用上面的代码替换任何基本模板程序的 display()方法,编译并执行它,生成以下输出 :
public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin(GL2.GL_QUADS); gl.glVertex3f( 0.0f,0.75f,0); gl.glVertex3f(-0.75f,0f,0); gl.glVertex3f(0f,-0.75f,0); gl.glVertex3f(0.75f,0f,0); gl.glEnd(); }
如果用上面的代码替换任何基本模板程序的 display()方法,编译并执行它,生成以下输出 :
public void display(GLAutoDrawable drawable) { final GL2 gl = drawable.getGL().getGL2(); gl.glBegin(GL2.GL_POLYGON); gl.glVertex3f(0f,0.5f,0f); gl.glVertex3f(-0.5f,0.2f,0f); gl.glVertex3f(-0.5f,-0.2f,0f); gl.glVertex3f(0f,-0.5f,0f); gl.glVertex3f(0f,0.5f,0f); gl.glVertex3f(0.5f,0.2f,0f); gl.glVertex3f(0.5f,-0.2f,0f); gl.glVertex3f(0f,-0.5f,0f); gl.glEnd(); }
如果用上面的代码替换任何基本模板程序的 display()方法,编译并执行它,生成以下输出 :