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📜  JOGL-照明

📅  最后修改于: 2020-11-13 04:56:49             🧑  作者: Mango

本章介绍如何使用JOGL将照明效果应用于对象。

要设置照明，请首先使用glEnable()方法启用照明。然后，使用GLLightingFunc接口的glLightfv (int light，int pname，float [] params，int params_offset)方法对对象进行照明。此方法采用四个参数。

下表描述了gllightfv()方法的参数。

Sr.No. Parameter Name and Description
1

Light

Specifies a light. The number of lights depends on the implementation, but at least eight lights are supported. It accepts ten values, those parameters are discussed in a separate table named Light Source Parameters given below.
2

Pname

Specifies a single valued light source parameter. For light source, there are ten parameters as discussed below.
3

Params

Specifies a pointer to the value or values that is set to the parameter pname of light source light.
4

Light source parameter

You can use any of the light source parameters given below.

光源参数

Sr.No. Parameter and Description
1

GL_AMBIENT

It contains the parameters that specify the ambient intensity of the light.
2

GL_DIFFUSE

It contains the parameters that specify the diffuse intensity of the light.
3

GL_SPECULAR

It contains the parameters that specify the specular intensity of the light.
4

GL_POSITION

It contains four integer or floating-point values that specify the position of the light in homogeneous object coordinates.
5

GL_SPOT_DIRECTION

It contains parameters that specify the direction of light in homogeneous object coordinates.
6

GL_SPOT_EXPONENT

Its parameters specify the intensity distribution of light.
7

GL_SPOT_CUTOFF

The single parameter of this specifies the maximum spread angle of the light.
8

GL_CONSTANT_ATTENUATION or GL_LINEAR_ATTENUATION or GL_QUADRATIC_ATTENUATION

You can use any of these attenuation factors, which is represented by a single value.

使用带有参数GL_LIGHTING的glEnable()和glDisable ()方法启用或禁用照明。

以下模板用于照明-

gl.glEnable(GL2.GL_LIGHTING); 
gl.glEnable(GL2.GL_LIGHT0);  
gl.glEnable(GL2.GL_NORMALIZE); 

float[] ambientLight = { 0.1f, 0.f, 0.f,0f };  // weak RED ambient 
gl.glLightfv(GL2.GL_LIGHT0, GL2.GL_AMBIENT, ambientLight, 0); 

float[] diffuseLight = { 1f,2f,1f,0f };  // multicolor diffuse 
gl.glLightfv(GL2.GL_LIGHT0, GL2.GL_DIFFUSE, diffuseLight, 0);

将光应用于旋转多边形

请按照给定的步骤将光线应用于旋转的多边形。

使用glRotate()方法旋转多边形

gl.glClear(GL2.GL_COLOR_BUFFER_BIT | GL2.GL_DEPTH_BUFFER_BIT); 
  
// Clear The Screen And The Depth Buffer  
gl.glLoadIdentity();  
                 
// Reset The View  
gl.glRotatef(rpoly, 0.0f, 1.0f, 0.0f);

让我们看一下程序，将光应用于旋转的多边形-

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; 

import com.jogamp.opengl.util.FPSAnimator; 
 
public class PolygonLighting implements GLEventListener { 
   private float rpoly;
    
   @Override 
    
   public void display( GLAutoDrawable drawable ) {
   
      final GL2 gl = drawable.getGL().getGL2(); 
      gl.glColor3f(1f,0f,0f); //applying red
      
      // Clear The Screen And The Depth Buffer 
      gl.glClear( GL2.GL_COLOR_BUFFER_BIT |  
      GL2.GL_DEPTH_BUFFER_BIT );   
      gl.glLoadIdentity();       // Reset The View    
      gl.glRotatef( rpoly, 0.0f, 1.0f, 0.0f ); 
        
      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(); 
        
      gl.glFlush(); 
      
      rpoly += 0.2f;  //assigning the angle 
      
      gl.glEnable( GL2.GL_LIGHTING );  
      gl.glEnable( GL2.GL_LIGHT0 );  
      gl.glEnable( GL2.GL_NORMALIZE );  

      // weak RED ambient 
      float[] ambientLight = { 0.1f, 0.f, 0.f,0f };  
      gl.glLightfv(GL2.GL_LIGHT0, GL2.GL_AMBIENT, ambient-Light, 0);  

      // multicolor diffuse 
      float[] diffuseLight = { 1f,2f,1f,0f };  
      gl.glLightfv( GL2.GL_LIGHT0, GL2.GL_DIFFUSE, diffuse-Light, 0 ); 
   }  
      
   @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 ); 
      PolygonLighting polygonlighting = new PolygonLighting(); 
      glcanvas.addGLEventListener( polygonlighting ); 
      glcanvas.setSize( 400, 400 ); 

      //creating frame 
      final JFrame frame = new JFrame (" Polygon lighting ");  

      //adding canvas to it 
      frame.getContentPane().add( glcanvas ); 
      frame.setSize( frame.getContentPane().getPreferredSize()); 
      frame.setVisible( true );  
                    
      //Instantiating and Initiating Animator 
      final FPSAnimator animator = new FPSAnimator(glcanvas, 300,true ); 
      animator.start();                     
      
   } //end of main 
    
} //end of class

如果编译并执行上述程序，它将生成以下输出。在这里，您可以观察带有照明的旋转多边形的各种快照。

多边形照明