Android OpenGL10 基本圖形繪製

原創 喝醉了的熊猫 2020-06-14 22:44

下面程序的opengl的圖形是根據Opengl1.0版本API進行的.

<a> : 首先繪製點:

<1> : 新建一個android studio工程,這個工程參考前一篇座標系的.工程名:PumpKinBasicGL10,主類如下:

package org.durian.pumpkinbasicgl10;

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

import org.durian.pumpkinbasicgl10.draw2d.PumpKinRenderer;
import org.durian.pumpkinbasicgl10.draw2d.dot.PumpkinDotRenderer;
import org.durian.pumpkinbasicgl10.draw2d.line.PumpKinLineRenderer;
import org.durian.pumpkinbasicgl10.draw2d.triangle.PumpKinTriangleRenderer;
import org.durian.pumpkinbasicgl10.draw3d.cube.PumpKinCubeRenderer;
import org.durian.pumpkinbasicgl10.draw3d.shapes.PumpKinPyramidRenderer;

public class MainActivity extends Activity {

    private GLSurfaceView mSurfaceView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        mSurfaceView=new GLSurfaceView(this);
        mSurfaceView.setRenderer(/*new PumpKinRenderer()*/new PumpkinDotRenderer()/*new PumpKinLineRenderer(this)*//*new PumpKinTriangleRenderer()*//*new PumpKinPyramidRenderer()*//*new PumpKinCubeRenderer()*/);
        setContentView(mSurfaceView/*R.layout.activity_main*/);
    }

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

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


<2> : 畫點類程序如下:

package org.durian.pumpkinbasicgl10.draw2d.dot;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/26.
 */
public class PumpKinDot {

    private FloatBuffer vertexsBuffer;

    private FloatBuffer colorsBuffer;

    //x,y,z
    private float[] vertexs=new float[]{
            1.0f,0.0f,0.0f,
            0.0f,1.0f,0.0f,
            -1.0f,0.0f,0.0f,
            0.0f,-1.0f,0.0f,
            0.5f,0.0f,0.0f,
            0.0f,0.5f,0.0f,
            -0.5f,0.0f,0.0f,
            0.0f,-0.5f,0.0f,
            0.0f,0.0f,0.0f,
            0.0f,0.0f,1.0f,
            0.0f,0.0f,-1.0f,
            0.0f,0.0f,0.5f,
            0.0f,0.0f,-0.5f,
            0.0f,0.0f,0.0f

    };

    //r,g,b,a
    private float[] colors={
            0.0f,1.0f,0.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            1.0f,1.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
            1.0f,1.0f,1.0f,1.0f,
    };

    public PumpKinDot(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertexs);
        vertexsBuffer.position(0);

        ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4);
        cbb.order(ByteOrder.nativeOrder());
        colorsBuffer=cbb.asFloatBuffer();
        colorsBuffer.put(colors);
        colorsBuffer.position(0);

    }

    public void draw(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);
        gl.glDrawArrays(GL10.GL_POINTS,0,vertexs.length/3);
        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

}
上面程序主要是注意

gl.glDrawArrays(GL10.GL_POINTS,0,vertexs.length/3);

第一個參數爲設置繪製圖形類型.第一篇博客已有說明.

程序在x,y,z軸上面繪製畫出多個點.

渲染的類:

package org.durian.pumpkinbasicgl10.draw2d.dot;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

import org.durian.pumpkinbasicgl10.draw2d.PumpKin;

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

/**
 * Created by Administrator on 2016/4/26.
 */
public class PumpkinDotRenderer implements GLSurfaceView.Renderer {

    private PumpKinDot pumpKinDot;
    private PumpKin pumpKin;

    public PumpkinDotRenderer() {

        pumpKinDot = new PumpKinDot();
        pumpKin=new PumpKin();
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if (height == 0) {
            height = 1;
        }
        float aspect = (float) width / height;

        gl.glViewport(0, 0, width, height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        gl.glTranslatef(0.0f, 0.0f, -6.0f);
        gl.glRotatef(45,1.0f,1.0f,1.0f);
        //pumpKin.draw(gl);
        pumpKinDot.draw(gl);


    }
}

上面對於的座標線:

//pumpKin.draw(gl);

被註釋了,這個繪製的座標線不是必須的,只是讓人可以更好定位三維空間位置,能夠看得見.

運行結果:


如果將座標系直線顯示出來:


上面的在程序中,做了座標變換:對座標做了旋轉變換.

gl.glRotatef(45,1.0f,1.0f,1.0f);

座標線條程序和前一篇一模一樣:

package org.durian.pumpkinbasicgl10.draw2d;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/28.
 */
public class PumpKin {

    private FloatBuffer vertexsBuffer;
    private FloatBuffer colorsBuffer;

    private ByteBuffer indicesBuffer;

    private float vertexs[]={
            -3.0f,0.0f,0.0f,
            3.0f,0.0f,0.0f,
            0.0f,-3.0f,0.0f,
            0.0f,3.0f,0.0f,
            0.0f,0.0f,-3.0f,
            0.0f,0.0f,3.0f
    };

    private float colors[]={
            1.0f,0.0f,0.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            0.0f,0.0f,1.0f,1.0f,
            0.0f,0.0f,1.0f,1.0f
    };

    private byte indices[]={0,1,2};

    public PumpKin(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertexs);
        vertexsBuffer.position(0);

        ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4);
        cbb.order(ByteOrder.nativeOrder());
        colorsBuffer=cbb.asFloatBuffer();
        colorsBuffer.put(colors);
        colorsBuffer.position(0);

    }

    public void draw(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);

        gl.glDrawArrays(GL10.GL_LINES,0,vertexs.length/3);

        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

}

package org.durian.pumpkinbasicgl10.draw2d;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

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

/**
 * Created by Administrator on 2016/4/28.
 */
public class PumpKinRenderer implements GLSurfaceView.Renderer {

    private PumpKin pumpKin;

    public PumpKinRenderer(){
        pumpKin=new PumpKin();
    }
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f,0.0f,0.0f,1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if(height==0){
            height=1;
        }
        float aspect=(float)width/height;

        gl.glViewport(0,0,width,height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        gl.glTranslatef(0.0f,0.0f,-2f);
        gl.glRotatef(45,1.0f,1.0f,1.0f);
        pumpKin.draw(gl);

    }
}

上面即是繪製點.


<b> : 下面介紹繪製直線,其實繪製直線前面已經有了,比如繪製座標直線.只需要在上面工程添加繪製line的類和渲染類

package org.durian.pumpkinbasicgl10.draw2d.line;

import android.util.Log;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/26.
 */
public class PumpKinLine {

    private FloatBuffer vertexsBuffer;
    private FloatBuffer colorsBuffer;
    private ByteBuffer indicesBuffer;

    private float[] vertexss={
            -1.0f,-1.0f,0.0f,
            1.0f,-1.0f,0.0f,
            -1.0f,1.0f,0.0f,
            1.0f,1.0f,0.0f
    };
    //x,y,z
    private float[] vertexs={
            0.0f,0.0f,0.0f,
            1.0f,0.0f,0.0f,
            0.0f,0.0f,0.0f,
            0.0f,1.0f,0.0f
    };
    //r,g,b,a
    private float[] colors={
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f
    };

    private byte[] indices={
            0,1,2
    };

    public PumpKinLine(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertexs);
        vertexsBuffer.position(0);


        ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4);
        cbb.order(ByteOrder.nativeOrder());
        colorsBuffer=cbb.asFloatBuffer();
        colorsBuffer.put(colors);
        colorsBuffer.position(0);

        indicesBuffer=ByteBuffer.allocateDirect(indices.length);
        indicesBuffer.put(indices);
        indicesBuffer.position(0);

    }

    public void draw(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);

        gl.glColor4f(1.0f,0.0f,0.0f,1.0f);
        gl.glDrawArrays(GL10.GL_LINES,0,vertexs.length/3);

        //gl.glDrawElements(GL10.GL_TRIANGLES,indices.length,GL10.GL_UNSIGNED_BYTE,indicesBuffer);
        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

}

繪製也可以通過:

gl.glDrawElements(GL10.GL_TRIANGLES,indices.length,GL10.GL_UNSIGNED_BYTE,indicesBuffer);

進行,只是這個方法需要提供繪製序列點indices數組.

繪製的直線的:

0.0f,0.0f,0.0f,
            1.0f,0.0f,0.0f,

這兩點連接的線

以及:

0.0f,0.0f,0.0f,
            0.0f,1.0f,0.0f

這兩天鏈接的線.

即兩條線分別沿x,y正方向.

對應的渲染類如下:

package org.durian.pumpkinbasicgl10.draw2d.line;

import android.content.Context;
import android.opengl.GLSurfaceView;
import android.opengl.GLU;

import org.durian.pumpkinbasicgl10.draw2d.PumpKin;

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

/**
 * Created by Administrator on 2016/4/26.
 */
public class PumpKinLineRenderer implements GLSurfaceView.Renderer {

    private PumpKinLine pumpKinLine;
    private PumpKin pumpKin;
    public PumpKinLineRenderer(){

        pumpKinLine=new PumpKinLine();
        pumpKin=new PumpKin();

    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f,0.0f,0.0f,1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if(height==0){
            height=1;
        }
        float aspect=(float)width/height;

        gl.glViewport(0,0,width,height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        //gl.glTranslatef(0.0f,0.0f,0.0f);
        gl.glTranslatef(0.0f,0.0f,-0.1f);
        //gl.glTranslatef(-3.0f,0.0f,-6.0f);
        //gl.glTranslatef(3.0f,0.0f,1.0f);
//        pumpKin.draw(gl);
        pumpKinLine.draw(gl);


    }

}


如果想顯示當前的座標線,可以將

//        pumpKin.draw(gl);

去掉註釋.


<c> : 繪製多邊形:代碼如下

package org.durian.pumpkinbasicgl10.draw2d.triangle;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/27.
 */
public class PumpKinTriangle {

    private FloatBuffer vertexsBuffer;
    private FloatBuffer vertexsaBuffer;
    private FloatBuffer colorsBuffer;
    private FloatBuffer colorsaBuffer;

    private ByteBuffer indicesBuffer;
    private ByteBuffer indicesaBuffer;

    //x,y,z
    private float[] vertexs={
        1.0f,0.0f,0.0f,
            0.0f,1.0f,0.0f,
                0.0f,0.0f,1.0f
    };

    private float[] vertexsa={
            1.0f,0.0f,0.0f,
            0.0f,1.0f,0.0f,
            0.0f,0.0f,1.0f,
            1.0f,0.0f,1.0f,
            0.5f,1.0f,0.0f,
            0.5f,1.0f,1.0f
    };

    //r,g,b,a
    private float[] colors={
        1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            0.0f,0.0f,1.0f,1.0f
    };

    private float[] colorsa={
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            0.0f,0.0f,1.0f,1.0f,
            1.0f,0.0f,0.0f,1.0f,
            0.0f,1.0f,0.0f,1.0f,
            0.0f,0.0f,1.0f,1.0f
    };

    private byte[] indices={0,1,2};

    private byte[] indicesa={0,1,2,3,4,5};


    public PumpKinTriangle(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertexs);
        vertexsBuffer.position(0);

        ByteBuffer vbba=ByteBuffer.allocateDirect(vertexsa.length*4);
        vbba.order(ByteOrder.nativeOrder());
        vertexsaBuffer=vbba.asFloatBuffer();
        vertexsaBuffer.put(vertexsa);
        vertexsaBuffer.position(0);

        ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4);
        cbb.order(ByteOrder.nativeOrder());
        colorsBuffer=cbb.asFloatBuffer();
        colorsBuffer.put(colors);
        colorsBuffer.position(0);

        ByteBuffer cbba=ByteBuffer.allocateDirect(colorsa.length*4);
        cbba.order(ByteOrder.nativeOrder());
        colorsaBuffer=cbba.asFloatBuffer();
        colorsaBuffer.put(colorsa);
        colorsaBuffer.position(0);

        indicesBuffer=ByteBuffer.allocateDirect(indices.length);
        indicesBuffer.order(ByteOrder.nativeOrder());
        indicesBuffer.put(indices);
        indicesBuffer.position(0);

        indicesaBuffer=ByteBuffer.allocateDirect(indicesa.length);
        indicesaBuffer.order(ByteOrder.nativeOrder());
        indicesaBuffer.put(indicesa);
        indicesaBuffer.position(0);

    }

    // type :GL10.GL_TRIANGLES
    public void draw(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);

        gl.glDrawArrays(GL10.GL_TRIANGLES,0,vertexs.length/3);

        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

    public void drawE(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);
        gl.glDrawElements(GL10.GL_TRIANGLES,indices.length,GL10.GL_UNSIGNED_BYTE,indicesBuffer);

        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

    public void drawNc(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

        gl.glColor4f(0.0f,1.0f,0.0f,1.0f);
        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);

        gl.glDrawArrays(GL10.GL_TRIANGLES,0,vertexs.length/3);

    }

    //type : GL10.GL_TRIANGLE_STRIP
    public void draw1(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsaBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsaBuffer);
        gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,0,vertexsa.length/3);

        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

    //type : GL10.GL_TRIANGLE_FAN
    public void draw1E(GL10 gl){

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsaBuffer);
        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsaBuffer);

        gl.glDrawElements(GL10.GL_TRIANGLE_FAN,indicesa.length,GL10.GL_UNSIGNED_BYTE,indicesaBuffer);

        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }

}


程序採用了兩種繪製圖像的方法:

gl.glDrawArrays

和:

gl.glDrawElements

這兩種繪製在前面大致說過了.

這裏主要介紹這兩個方法的第一個參數:分別是GL_TRIANGLES、GL_TRIANGLE_STRIP和GL_TRIANGLE_FAN

圖片出處:http://blog.csdn.net/xiajun07061225/article/details/7455283,參考具體說明:

GL_TRIANGLES是以每三個頂點繪製一個三角形。第一個三角形使用頂點v0,v1,v2,第二個使用v3,v4,v5,以此類推。如果頂點的個數n不是3的倍數，那麼最後的1個或者2個頂點會被忽略。

GL_TRIANGLE_STRIP則稍微有點複雜。
其規律是：
構建當前三角形的頂點的連接順序依賴於要和前面已經出現過的2個頂點組成三角形的當前頂點的序號的奇偶性（如果從0開始）：
如果當前頂點是奇數：
組成三角形的頂點排列順序：T = [n-1 n-2 n].
如果當前頂點是偶數：
組成三角形的頂點排列順序：T = [n-2 n-21 n].
以上圖爲例，第一個三角形，頂點v2序號是2，是偶數，則頂點排列順序是v0,v1,v2。第二個三角形，頂點v3序號是3，是奇數，則頂點排列順序是v2,v1,v3,第三個三角形，頂點v4序號是4，是偶數，則頂點排列順序是v2,v3,v4,以此類推。
這個順序是爲了保證所有的三角形都是按照相同的方向繪製的，使這個三角形串能夠正確形成表面的一部分。對於某些操作，維持方向是很重要的，比如剔除。
注意：頂點個數n至少要大於3，否則不能繪製任何三角形。

GL_TRIANGLE_FAN與GL_TRIANGLE_STRIP類似，不過它的三角形的頂點排列順序是T = [n-1 n-2 n].各三角形形成一個扇形序列

還有一個更加具體的可以參考,非常好:

http://blog.csdn.net/gisxs/article/details/16897229

對應渲染類:

package org.durian.pumpkinbasicgl10.draw2d.triangle;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

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

/**
 * Created by Administrator on 2016/4/27.
 */
public class PumpKinTriangleRenderer implements GLSurfaceView.Renderer {

    private PumpKinTriangle pumpKinTriangle;
    public PumpKinTriangleRenderer(){

        pumpKinTriangle=new PumpKinTriangle();

    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f,0.0f,0.0f,1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if(height==0){
            height=1;
        }
        float aspect=(float)width/height;

        gl.glViewport(0,0,width,height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        gl.glTranslatef(0.0f,0.0f,-6.0f);

        pumpKinTriangle.draw1(gl);

    }
}

如果調用draw1方法,運行結果如下:


如果將渲染類中程序修改:

//        pumpKinTriangle.draw1(gl);
        pumpKinTriangle.draw1E(gl);


運行結果:



上面大致介紹了基本二維圖形的繪製.

下面介紹三維圖形,三維圖形其實和二維在程序上面沒什麼區別,只是需要注意z軸了,座標方式差不多.三維圖形基本也是由基本二維圖形構成的.

<d> : 繪製金字塔模型:

package org.durian.pumpkinbasicgl10.draw3d.shapes;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/28.
 */
public class PumpKinPyramid {

    private FloatBuffer vertexsBuffer;
    private FloatBuffer colorsBuffer;

    private ByteBuffer indicesBuffer;

    // 5 vertices of the pyramid in (x,y,z)
    private float[] vertexs={
            -1.0f, -1.0f, -1.0f,  // 0. left-bottom-back
            1.0f, -1.0f, -1.0f,  // 1. right-bottom-back
            1.0f, -1.0f,  1.0f,  // 2. right-bottom-front
            -1.0f, -1.0f,  1.0f,  // 3. left-bottom-front
            0.0f,  1.0f,  0.0f   // 4. top
    };

    // Colors of the 5 vertices in RGBA
    private float[] colors={
            0.0f, 0.0f, 1.0f, 1.0f,  // 0. blue
            0.0f, 1.0f, 0.0f, 1.0f,  // 1. green
            0.0f, 0.0f, 1.0f, 1.0f,  // 2. blue
            0.0f, 1.0f, 0.0f, 1.0f,  // 3. green
            1.0f, 0.0f, 0.0f, 1.0f   // 4. red
    };

    private byte indices[]={
            2, 4, 3,   // front face (CCW)
            1, 4, 2,   // right face
            0, 4, 1,   // back face
            4, 0, 3    // left face
    };

    public PumpKinPyramid(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertexs.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertexs);
        vertexsBuffer.position(0);

        ByteBuffer cbb=ByteBuffer.allocateDirect(colors.length*4);
        cbb.order(ByteOrder.nativeOrder());
        colorsBuffer=cbb.asFloatBuffer();
        colorsBuffer.put(colors);
        colorsBuffer.position(0);

        indicesBuffer=ByteBuffer.allocateDirect(indices.length);
        indicesBuffer.order(ByteOrder.nativeOrder());
        indicesBuffer.put(indices);
        indicesBuffer.position(0);

    }

    public void draw(GL10 gl){

        gl.glFrontFace(GL10.GL_CCW);

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glEnableClientState(GL10.GL_COLOR_ARRAY);

        gl.glColorPointer(4,GL10.GL_FLOAT,0,colorsBuffer);
        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);

        gl.glDrawElements(GL10.GL_TRIANGLE_STRIP,indices.length,GL10.GL_UNSIGNED_BYTE,indicesBuffer);

        gl.glDisableClientState(GL10.GL_COLOR_ARRAY);
        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);

    }


}

其中:

gl.glFrontFace(GL10.GL_CCW);

改程序設置:設置逆時針方向爲正面.

上面的程序了vertexs頂點數組,可以很難搞清,等下在渲染器中添加座標,然後再來對應上面的座標點就瞭解了.
下面給出對應的渲染類:

package org.durian.pumpkinbasicgl10.draw3d.shapes;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

import org.durian.pumpkinbasicgl10.draw2d.PumpKin;

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

/**
 * Created by Administrator on 2016/4/28.
 */
public class PumpKinPyramidRenderer implements GLSurfaceView.Renderer {

    private PumpKinPyramid pumpKinPyramid;
    private PumpKin pumpKin;

    public PumpKinPyramidRenderer(){

        pumpKinPyramid=new PumpKinPyramid();
        pumpKin=new PumpKin();

    }
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f,0.0f,0.0f,1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if(height==0){
            height=1;
        }
        float aspect=(float)width/height;

        gl.glViewport(0,0,width,height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        gl.glTranslatef(0.0f, 0.0f, -8.0f);
        gl.glRotatef(45,1.0f,1.0f,1.0f);
        pumpKinPyramid.draw(gl);
        pumpKin.draw(gl);

    }
}


運行結果:




一個金字塔形的立體需要4個面,一共需要5個頂點,主要是要定好座標原點,比如上面座標原點在金字塔中心位置.比如上面對着我們的綠色角,對應的頂點座標(-1.0f, -1.0f,  1.0f),紅色頂點在y軸(紅線是x軸,綠色y軸,藍色z軸)位置(0.0f,  1.0f,  0.0f),剛好綠線(y軸)結果頂點,其他的一次類推.


<e> : 下面介紹立方體,基本上都是類似做法,立方體有八個座標,同上,原點(0,0,0)設置在立方體中心位置,程序如下:

package org.durian.pumpkinbasicgl10.draw3d.cube;

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

import javax.microedition.khronos.opengles.GL10;

/**
 * Created by Administrator on 2016/4/29.
 */
public class PumpKinCube {

    private FloatBuffer vertexsBuffer;

    private FloatBuffer lvertexsBuffer;
    private FloatBuffer lcolorsBuffer;

    /*
    * eight vertex as following :
    * V0 : -1.0f, -1.0f,  1.0f
    * V1 : 1.0f, -1.0f,  1.0f
    * V2 : -1.0f,  1.0f,  1.0f
    * V3 : -1.0f, -1.0f, -1.0f
    * V4 : -1.0f, -1.0f, -1.0f
    * V5 : -1.0f,  1.0f, -1.0f
    * V6 : 1.0f, -1.0f, -1.0f
    * V7 : 1.0f,  1.0f, -1.0f
    * 三維座標系原點在這個立方體中心
    * */
    private float[] vertices = {  // Vertices of the 6 faces
            // FRONT
            -1.0f, -1.0f,  1.0f,  // 0. left-bottom-front
            1.0f, -1.0f,  1.0f,  // 1. right-bottom-front
            -1.0f,  1.0f,  1.0f,  // 2. left-top-front
            1.0f,  1.0f,  1.0f,  // 3. right-top-front
            // BACK
            1.0f, -1.0f, -1.0f,  // 6. right-bottom-back
            -1.0f, -1.0f, -1.0f,  // 4. left-bottom-back
            1.0f,  1.0f, -1.0f,  // 7. right-top-back
            -1.0f,  1.0f, -1.0f,  // 5. left-top-back
            // LEFT
            -1.0f, -1.0f, -1.0f,  // 4. left-bottom-back
            -1.0f, -1.0f,  1.0f,  // 0. left-bottom-front
            -1.0f,  1.0f, -1.0f,  // 5. left-top-back
            -1.0f,  1.0f,  1.0f,  // 2. left-top-front
            // RIGHT
            1.0f, -1.0f,  1.0f,  // 1. right-bottom-front
            1.0f, -1.0f, -1.0f,  // 6. right-bottom-back
            1.0f,  1.0f,  1.0f,  // 3. right-top-front
            1.0f,  1.0f, -1.0f,  // 7. right-top-back
            // TOP
            -1.0f,  1.0f,  1.0f,  // 2. left-top-front
            1.0f,  1.0f,  1.0f,  // 3. right-top-front
            -1.0f,  1.0f, -1.0f,  // 5. left-top-back
            1.0f,  1.0f, -1.0f,  // 7. right-top-back
            // BOTTOM
            -1.0f, -1.0f, -1.0f,  // 4. left-bottom-back
            1.0f, -1.0f, -1.0f,  // 6. right-bottom-back
            -1.0f, -1.0f,  1.0f,  // 0. left-bottom-front
            1.0f, -1.0f,  1.0f   // 1. right-bottom-front
    };

    private float[][] colors = {  // Colors of the 6 faces
            {1.0f, 0.5f, 0.0f, 1.0f},  // 0. orange
            {1.0f, 0.0f, 1.0f, 1.0f},  // 1. violet
            {0.0f, 1.0f, 0.0f, 1.0f},  // 2. green
            {0.0f, 0.0f, 1.0f, 1.0f},  // 3. blue
            {1.0f, 0.0f, 0.0f, 1.0f},  // 4. red
            {1.0f, 1.0f, 0.0f, 1.0f}   // 5. yellow
    };

    public PumpKinCube(){

        ByteBuffer vbb=ByteBuffer.allocateDirect(vertices.length*4);
        vbb.order(ByteOrder.nativeOrder());
        vertexsBuffer=vbb.asFloatBuffer();
        vertexsBuffer.put(vertices);
        vertexsBuffer.position(0);

    }

    public void draw(GL10 gl){

        gl.glFrontFace(GL10.GL_CCW);
        gl.glEnable(GL10.GL_CULL_FACE);
        gl.glCullFace(GL10.GL_BACK);

        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);

        gl.glVertexPointer(3,GL10.GL_FLOAT,0,vertexsBuffer);

        for(int i=0;i<6;i++){

            gl.glColor4f(colors[i][0],colors[i][1],colors[i][2],colors[i][3]);
            gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP,i*4,4);

        }

        gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
        gl.glDisable(GL10.GL_CULL_FACE);

    }

}

特別說一下:

gl.glFrontFace(GL10.GL_CCW);
        gl.glEnable(GL10.GL_CULL_FACE);
        gl.glCullFace(GL10.GL_BACK);
gl.glEnable(GL10.GL_CULL_FACE);
設置openggl有剔除效果，就是看不到的面就不畫，當然可以增加效率
gl.glCullFace(GL10.GL_BACK);
設置背面被剔除，不畫.
gl.glFrontFace(GL10.GL_CCW);
設置逆時針方向爲正面


對應渲染器類:

package org.durian.pumpkinbasicgl10.draw3d.cube;

import android.opengl.GLSurfaceView;
import android.opengl.GLU;

import org.durian.pumpkinbasicgl10.draw2d.PumpKin;

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

/**
 * Created by Administrator on 2016/4/29.
 */
public class PumpKinCubeRenderer implements GLSurfaceView.Renderer {

    private PumpKinCube pumpKinCube;
    private PumpKin pumpKin;

    private int cubeAngle=0;
    private int cubeSpeech=1;

    public PumpKinCubeRenderer(){
        pumpKinCube=new PumpKinCube();
        pumpKin=new PumpKin();
    }
    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {

        gl.glClearColor(0.0f,0.0f,0.0f,1.0f);
        gl.glClearDepthf(1.0f);
        gl.glEnable(GL10.GL_DEPTH_TEST);
        gl.glDepthFunc(GL10.GL_LEQUAL);
        gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,GL10.GL_NICEST);
        gl.glShadeModel(GL10.GL_SMOOTH);
        gl.glDisable(GL10.GL_DITHER);

    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {

        if(height==0){
            height=1;
        }
        float aspect=(float)width/height;

        gl.glViewport(0,0,width,height);

        gl.glMatrixMode(GL10.GL_PROJECTION);
        gl.glLoadIdentity();
        GLU.gluPerspective(gl, 45, aspect, 0.1f, 100.0f);

        gl.glMatrixMode(GL10.GL_MODELVIEW);
        gl.glLoadIdentity();

    }

    @Override
    public void onDrawFrame(GL10 gl) {

        gl.glClear(GL10.GL_COLOR_BUFFER_BIT|GL10.GL_DEPTH_BUFFER_BIT);

        gl.glLoadIdentity();
        gl.glTranslatef(0.0f,0.0f,-6.0f);
        gl.glRotatef(cubeAngle,1.0f,1.0f,1.0f);
        gl.glScalef(0.8f,0.8f,0.8f);
        pumpKinCube.draw(gl);
        pumpKin.draw(gl);

        cubeAngle+=cubeSpeech;
    }
}


運行如下:




至於紋理部分將在後面單獨給出來簡述.


















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OpenGL的承載體是GLSurfaceView,而GLSurfaceView類在很多方面類似於View,那麼它同樣具有與View的一些待遇,比如也能夠響應KeyEvent,MotionEvent事件等等,從前面幾篇中,有很多立方體的圖形

喝醉了的熊猫 2020-06-14 22:45:07

Android OpenGL10 紋理

前面一篇中簡述了基本圖形的繪製,並且給出着色,下面看看如何在一個立方體上面覆蓋一層紋理,就像在地板上貼了一層地板磚的效果. 同樣新建一個android studio工程,PumpKinBasicTexture工程: 主類如下: packa

喝醉了的熊猫 2020-06-14 22:45:07

Android OpenGL20 世界座標系,屏幕座標系,紋理座標系

在  http://blog.csdn.net/qq_31726827/article/details/51265186這一篇大概介紹了座標系,

喝醉了的熊猫 2020-06-14 22:45:07

Android OpenGL20 模型，視圖，投影與Viewport

對於很多初學者,視圖投影之類非常的難理解,然而這個東西非常非常的重要,如果不是非常清楚,根本無法定位3D Object(空間座標)和觀察角度(觀察角度不一樣,效果就不一樣),自己閱博無數,發現了一篇非常棒的blog文章: http://b

喝醉了的熊猫 2020-06-14 22:45:07

Android OpenGL 座標系

計算機中任何繪圖都離不開座標系只是在每種繪圖中座標系形式有些差異,比如平時做android的View,在自定義View中繪製直線,那麼這個時候默認的是採用的是屏幕座標系,即座標原點在屏幕左上角,X軸向右,Y向下: 而在opengl中採用

喝醉了的熊猫 2020-06-14 22:45:07