Android OpenGL ES学习

Android用的是OpenGL图形函数库，它可以跨平台。
OpenGL的定义：OpenGL（Open Graphics Library）是个定义了一个跨编程语言、跨平台的编程接口的规格，它用于三维图象（二维的亦可）。OpenGL是个专业的图形程序接口，是一个功能强大，调用方便的底层图形库。
Android所用到的是它的一个子集OpenGL ES（OpenGL for Embedded Systems（嵌入式系统））就是OpenGL的嵌入式版本。
1.主activity

package com.jftt.opengl;

import android.app.Activity;
import android.os.Bundle;

public class OpenGL extends Activity {
	private static final String TAG = OpenGL.class.getSimpleName();
	private VortexView vortexView;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		vortexView = new VortexView(this);
		setContentView(vortexView);
	}

	@Override
	protected void onPause() {
		super.onPause();
		vortexView.onPause();
	}

	@Override
	protected void onResume() {
		super.onResume();
		vortexView.onResume();
	}
}

 

2.继承GLSurfaceView类的自己的View

package com.jftt.opengl;

import android.content.Context;
import android.opengl.GLSurfaceView;
import android.view.MotionEvent;

public class VortexView extends GLSurfaceView {
	private static final String LOG_TAG = VortexView.class.getSimpleName();
	private VortexRenderer renderer;

	public VortexView(Context context) {
		super(context);
		renderer = new VortexRenderer();
		setRenderer(renderer);
	}
	
	@Override
	public boolean onTouchEvent(final MotionEvent event) {
		queueEvent(new Runnable() {
			@Override
			public void run() {
				renderer.setColor(event.getX() / getWidth(), event.getY() / getHeight(), 1.0f);
				renderer.setAngle(event.getX() / 10);
			}
		});
		return super.onTouchEvent(event);
	}
}

 

3.实现渲染器renderer类

package com.jftt.opengl;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

import android.opengl.GLSurfaceView;

public class VortexRenderer implements GLSurfaceView.Renderer {
	private static final String TAG = VortexRenderer.class.getSimpleName();

	private float red = 0f;
	private float green = 0f;
	private float blue = 0f;

	private ShortBuffer indexBuffer;
	private FloatBuffer vertexBuffer;
	private short[] indicesArray = { 0, 1, 2 };
	private int numberOfVertices = 3;
	
	private float angle;
	
	private void initTriangle() {
		ByteBuffer vbb = ByteBuffer.allocateDirect(numberOfVertices * 3 * 4);
		vbb.order(ByteOrder.nativeOrder());
		vertexBuffer = vbb.asFloatBuffer();

		ByteBuffer ibb = ByteBuffer.allocateDirect(numberOfVertices * 2);
		ibb.order(ByteOrder.nativeOrder());
		indexBuffer = ibb.asShortBuffer();

		float[] coords = { -0.5f, -0.5f, 0f, 0.5f, -0.5f, 0f, 0f, 0.5f, 0f };

		vertexBuffer.put(coords);
		indexBuffer.put(indicesArray);

		vertexBuffer.position(0);
		indexBuffer.position(0);
	}

	public void setColor(float red, float green, float blue) {
		this.red = red;
		this.green = green;
		this.blue = blue;
	}
	
	public void setAngle(float angle){
		this.angle = angle;
	}

	@Override
	public void onSurfaceCreated(GL10 gl, EGLConfig config) {
		gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
		initTriangle();
	}

	@Override
	public void onSurfaceChanged(GL10 gl, int width, int height) {
		gl.glViewport(0, 0, width, height);
	}

	@Override
	public void onDrawFrame(GL10 gl) {
		gl.glClearColor(red, green, blue, 1.0f);
		gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
		gl.glRotatef(angle, 0f, 1f, 0f);
		gl.glColor4f(0.5f, 0f, 0f, 0.5f);
		gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);
		gl.glDrawElements(GL10.GL_TRIANGLES, numberOfVertices, GL10.GL_UNSIGNED_SHORT, indexBuffer);
	}
}

 

4.封装的三角形的类

package com.jftt.opengl;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import java.util.Random;

public class Triangle {
	private short[] myIndecesArray = { 0, 1, 2 };
	private int numberOfVertices = 3;

	private float red = 0f;
	private float green = 0f;
	private float blue = 0f;

	// a raw buffer to hold indices allowing a reuse of points.
	private ShortBuffer indexBuffer;
	// a raw buffer to hold the vertices
	private FloatBuffer vertexBuffer;
	private Random random = new Random();

	public Triangle() {
		red = random.nextFloat();
		red = red - (float) Math.floor(red);
		green = random.nextFloat();
		green = green - (float) Math.floor(green);
		blue = random.nextFloat();
		blue = blue - (float) Math.floor(blue);

		ByteBuffer vbb = ByteBuffer.allocateDirect(numberOfVertices * 3 * 4);
		vbb.order(ByteOrder.nativeOrder());
		vertexBuffer = vbb.asFloatBuffer();

		ByteBuffer ibb = ByteBuffer.allocateDirect(numberOfVertices * 2);
		ibb.order(ByteOrder.nativeOrder());
		indexBuffer = ibb.asShortBuffer();

		float[] coords = { randomValue(red), randomValue(red),
				randomValue(red), randomValue(green), randomValue(green),
				randomValue(green), randomValue(blue), randomValue(blue),
				randomValue(blue) };

		for (int i = 0; i < numberOfVertices; i++) {
			for (int j = 0; j < 3; j++) {
				vertexBuffer.put(coords[i * 3 + j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			indexBuffer.put(myIndecesArray[i]);
		}
		vertexBuffer.position(0);
		indexBuffer.position(0);
	}

	private float randomValue(float value) {
		int tmp = random.nextInt(2);
		if (tmp == 0) {
			tmp = -1;
		}
		return value * tmp;
	}

	public FloatBuffer getVertexBuffer() {
		return vertexBuffer;
	}

	public ShortBuffer getIndexBuffer() {
		return indexBuffer;
	}

	public int getNumberOfVertices() {
		return numberOfVertices;
	}

	public float getGreen() {
		return green;
	}

	public float getRed() {
		return red;
	}

	public float getBlue() {
		return blue;
	}
}