android opengles光照效果-散射光

来源：互联网发布：京东域名买谁的编辑：程序博客网时间：2024/05/02 01:15

向量的模:http://www.baike.com/wiki/%E5%90%91%E9%87%8F%E7%9A%84%E6%A8%A1
三维向量的模为 根号x^2 + y^2 + z^2
球面任意一点到球心的距离都是半径R 所以x^2 + y^2 + z^2 = R^2
向量的运算:http://blog.csdn.net/he_wen_jian/article/details/25533829
求法向量:http://blog.csdn.net/lidec/article/details/51873647
opengles光照总结:http://blog.csdn.net/kesalin/article/details/8451595

散射光比环境光稍复杂，需要用到以上的一些向量知识
散射光的计算公式:
散射光照结果=材质的反射系数 x 环境光强度 x max(0, dot(N, L))
N为顶点法向量 L为光源向量

demo:

import java.io.ByteArrayOutputStream;import java.io.InputStream;import java.nio.ByteBuffer;import java.nio.ByteOrder;import java.nio.FloatBuffer;import java.util.ArrayList;import javax.microedition.khronos.egl.EGLConfig;import javax.microedition.khronos.opengles.GL10;import android.app.Activity;import android.content.Context;import android.opengl.GLES20;import android.opengl.GLSurfaceView;import android.opengl.Matrix;import android.os.Bundle;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(new MSur(this));    }}class MSur extends GLSurfaceView {    Render render;    public MSur(Context context) {        super(context);        this.setEGLContextClientVersion(2);        render = new Render(context);        setRenderer(render);        this.setRenderMode(GLSurfaceView.RENDERMODE_CONTINUOUSLY);    }}class Render implements GLSurfaceView.Renderer {    private static final float r=0.8f;    //TODO 1 设置光源位置    private static final float LIGHT[]={1.0f, 0.5f, 1.5f};    private int vCount;    private Context ctx;    private FloatBuffer fbVertex;    private FloatBuffer fbNormal;    private FloatBuffer fbLight;    static float[] mMMatrix = new float[16];    int mProgram;// 自定义渲染管线程序id    int muMVPMatrixHandle;// 总变换矩阵引用id    int maPositionHandle; // 顶点位置属性引用id    int maNormalHandle; //顶点法向量属性引用    int maLightLocationHandle;//光源位置属性引用    public static float[] mProjMatrix = new float[16];// 4x4矩阵 投影用    public static float[] mVMatrix = new float[16];// 摄像机位置朝向9参数矩阵    public static float[] mMVPMatrix;// 最后起作用的总变换矩阵    public Render(Context ctx) {        super();        this.ctx = ctx;    }    @Override    public void onSurfaceCreated(GL10 gl, EGLConfig config) {        GLES20.glClearColor(0f, 0f, 0f, 1.0f);        initVertex();        initShader();        GLES20.glEnable(GLES20.GL_DEPTH_TEST);    }    @Override    public void onSurfaceChanged(GL10 gl, int width, int height) {        GLES20.glViewport(0, 0, width, height);        float ratio = (float) width / height;        Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 1, 10);        Matrix.setLookAtM(mVMatrix, 0, 0, 0, 3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);    }    @Override    public void onDrawFrame(GL10 gl) {        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);        draw();    }    public void draw() {        GLES20.glUseProgram(mProgram);        Matrix.setRotateM(mMMatrix, 0, 0, 0, 1, 0);        mMVPMatrix = new float[16];        Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);        Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);        GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);        //TODO 6 将光源位置传入着色器程序        GLES20.glUniform3fv(maLightLocationHandle, 1, fbLight);        GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 3 * 4, fbVertex);        //TODO 7 将顶点法向量数据传入渲染管线        GLES20.glVertexAttribPointer(maNormalHandle, 3, GLES20.GL_FLOAT, false, 3 * 4, fbNormal);        GLES20.glEnableVertexAttribArray(maPositionHandle);        //TODO 8 启用顶点法向量数据        GLES20.glEnableVertexAttribArray(maNormalHandle);        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vCount);    }    //初始化数据    private void initVertex() {        ArrayList<Float> alVertix = new ArrayList<Float>();        final int angleSpan = 10;// 将球进行单位切分的角度        for (int vAngle = -90; vAngle < 90; vAngle = vAngle + angleSpan)// 垂直方向angleSpan度一份        {            for (int hAngle = 0; hAngle <= 360; hAngle = hAngle + angleSpan)// 水平方向angleSpan度一份            {                float x0 = (float) (r * Math.cos(Math.toRadians(vAngle)) * Math.cos(Math.toRadians(hAngle)));                float y0 = (float) (r * Math.cos(Math.toRadians(vAngle)) * Math.sin(Math.toRadians(hAngle)));                float z0 = (float) (r * Math.sin(Math .toRadians(vAngle)));                float x1 = (float) (r * Math.cos(Math.toRadians(vAngle)) * Math.cos(Math.toRadians(hAngle + angleSpan)));                float y1 = (float) (r * Math.cos(Math.toRadians(vAngle)) * Math.sin(Math.toRadians(hAngle + angleSpan)));                float z1 = (float) (r  * Math.sin(Math.toRadians(vAngle)));                float x2 = (float) (r * Math.cos(Math.toRadians(vAngle + angleSpan)) * Math.cos(Math.toRadians(hAngle + angleSpan)));                float y2 = (float) (r * Math.cos(Math.toRadians(vAngle + angleSpan)) * Math.sin(Math.toRadians(hAngle + angleSpan)));                float z2 = (float) (r  * Math.sin(Math.toRadians(vAngle + angleSpan)));                float x3 = (float) (r * Math.cos(Math.toRadians(vAngle + angleSpan)) * Math.cos(Math.toRadians(hAngle)));                float y3 = (float) (r * Math.cos(Math.toRadians(vAngle + angleSpan)) * Math.sin(Math.toRadians(hAngle)));                float z3 = (float) (r * Math.sin(Math.toRadians(vAngle + angleSpan)));                alVertix.add(x1);                alVertix.add(y1);                alVertix.add(z1);                alVertix.add(x3);                alVertix.add(y3);                alVertix.add(z3);                alVertix.add(x0);                alVertix.add(y0);                alVertix.add(z0);                alVertix.add(x1);                alVertix.add(y1);                alVertix.add(z1);                alVertix.add(x2);                alVertix.add(y2);                alVertix.add(z2);                alVertix.add(x3);                alVertix.add(y3);                alVertix.add(z3);            }        }        vCount = alVertix.size() / 3;        float vertices[]=new float[alVertix.size()];        for (int i=0;i<vertices.length;i++) {            vertices[i]=alVertix.get(i);        }        ByteBuffer bbv = ByteBuffer.allocateDirect(vertices.length * 4);        bbv.order(ByteOrder.nativeOrder());        fbVertex = bbv.asFloatBuffer();        fbVertex.put(vertices);        fbVertex.position(0);        //TODO 4 法向量        ByteBuffer bbn = ByteBuffer.allocateDirect(vertices.length * 4);        bbn.order(ByteOrder.nativeOrder());        fbNormal = bbn.asFloatBuffer();        fbNormal.put(vertices);        fbNormal.position(0);        //TODO 5 光源位置        ByteBuffer bbl = ByteBuffer.allocateDirect(LIGHT.length * 4);        bbl.order(ByteOrder.nativeOrder());        fbLight = bbl.asFloatBuffer();        fbLight.put(LIGHT);        fbLight.position(0);    }    //初始化shader    private void initShader() {        String vertex = loadSH("vertex.sh");        String shader = loadSH("frag.sh");        int verS = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);        if (verS != 0) {            GLES20.glShaderSource(verS, vertex);            GLES20.glCompileShader(verS);        }        int fragS = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);        if (fragS != 0) {            GLES20.glShaderSource(fragS, shader);            GLES20.glCompileShader(fragS);        }        mProgram = GLES20.glCreateProgram();        if (mProgram != 0) {            GLES20.glAttachShader(mProgram, verS);            GLES20.glAttachShader(mProgram, fragS);            GLES20.glLinkProgram(mProgram);        }        maPositionHandle = GLES20.glGetAttribLocation(mProgram, "aPosition");        muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");        //TODO 2 获取程序中顶点法向量属性引用        maNormalHandle= GLES20.glGetAttribLocation(mProgram, "aNormal");        //TODO 3 获取程序中光源位置引用        maLightLocationHandle=GLES20.glGetUniformLocation(mProgram, "uLightLocation");    }    //将sh文件加载进来    private String loadSH(String fname) {        String result = null;        try {            InputStream in = ctx.getAssets().open(fname);            int ch = 0;            ByteArrayOutputStream baos = new ByteArrayOutputStream();            while ((ch = in.read()) != -1) {                baos.write(ch);            }            byte[] buff = baos.toByteArray();            baos.close();            in.close();            result = new String(buff, "UTF-8");            result = result.replaceAll("\\r\\n", "\n");        } catch (Exception e) {            e.printStackTrace();        }        return result;    }}

vertex.sh

uniform mat4 uMVPMatrix;                        //总变换矩阵uniform vec3 uLightLocation;                    //光源位置attribute vec3 aPosition;                       //顶点位置attribute vec3 aNormal;                         //顶点法向量varying vec4 vDiffuse;                          //用于传递给片元着色器的散射光分量void main()     {                                       gl_Position = uMVPMatrix * vec4(aPosition,1);    vec4 vAmbient = vec4(0.9, 0.9, 0.9, 1.0);       //设置环境光强度    vec3 normalTarget=aPosition+aNormal;    vec3 newNormal=(vec4(normalTarget,1)).xyz-(vec4(aPosition,1)).xyz;      //求出法向量    newNormal=normalize(newNormal);                     //向量规格化    vec3 vp= normalize(uLightLocation-(vec4(aPosition,1)).xyz);             //计算从表面点到光源位置的向量    vp=normalize(vp);                                   //向量规格化    float nDotViewPosition=max(0.0, dot(newNormal,vp));     //求法向量与vp向量的点积与0的最大值    vDiffuse=vAmbient*nDotViewPosition;             //计算散射光的最终强度}

frag.sh

precision mediump float;varying vec4 vDiffuse;  //用于传递给片元着色器的散射光分量void main()                         {    vec4 vFinalColor = vec4(1.0, 0.0, 1.0, 0.0);    gl_FragColor = vFinalColor * vDiffuse;  //通过散射光分量获得最终颜色}

效果:
这里写图片描述

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