Android OpenGLES 绘制图片纹理

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字数统计: 1,298字 | 阅读时长 ≈ 7分钟
  1. 把shader代码写入raw里面

vertex_shader.glsl

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attribute vec4 av_Position;//顶点位置
attribute vec2 af_Position;//纹理位置
varying vec2 v_texPo;//纹理位置  与fragment_shader交互
void main() {
    v_texPo = af_Position;
    gl_Position = av_Position;
}

fragment_shader.glsl

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precision mediump float;//精度 为float
varying vec2 v_texPo;//纹理位置  接收于vertex_shader
uniform sampler2D sTexture;//纹理
void main() {
    gl_FragColor=texture2D(sTexture, v_texPo);
}
  1. 写入数据,注意纹理映射

纹理坐标系

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import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLES20;
import android.opengl.GLUtils;

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


//纹理  根据坐标系映射
public class BitmapTexture {


    //顶点坐标
    static float vertexData[] = {   // in counterclockwise order:
            -1f, -1f, 0.0f, // bottom left
            1f, -1f, 0.0f, // bottom right
            -1f, 1f, 0.0f, // top left
            1f, 1f, 0.0f,  // top right
    };

    //纹理坐标  对应顶点坐标  与之映射
    static float textureData[] = {   // in counterclockwise order:
            0f, 1f, 0.0f, // bottom left
            1f, 1f, 0.0f, // bottom right
            0f, 0f, 0.0f, // top left
            1f, 0f, 0.0f,  // top right
    };

    //每一次取点的时候取几个点
    static final int COORDS_PER_VERTEX = 3;

    private final int vertexCount = vertexData.length / COORDS_PER_VERTEX;
    //每一次取的总的点 大小
    private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex


    private Context context;

    //位置
    private FloatBuffer vertexBuffer;
    //纹理
    private FloatBuffer textureBuffer;
    private int program;
    private int avPosition;
    //纹理位置
    private int afPosition;
    //纹理id
    private int textureId;


    public BitmapTexture(Context context) {
        this.context = context;

        vertexBuffer = ByteBuffer.allocateDirect(vertexData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(vertexData);
        vertexBuffer.position(0);

        textureBuffer = ByteBuffer.allocateDirect(textureData.length * 4)
                .order(ByteOrder.nativeOrder())
                .asFloatBuffer()
                .put(textureData);
        textureBuffer.position(0);
    }


    public void onSurfaceCreated() {
        String vertexSource = ShaderUtil.readRawTxt(context, R.raw.vertex_shader);
        String fragmentSource = ShaderUtil.readRawTxt(context, R.raw.fragment_shader);
        program = ShaderUtil.createProgram(vertexSource, fragmentSource);

        if (program > 0) {
            //获取顶点坐标字段
            avPosition = GLES20.glGetAttribLocation(program, "av_Position");
            //获取纹理坐标字段
            afPosition = GLES20.glGetAttribLocation(program, "af_Position");
            int[] textureIds = new int[1];
            //创建纹理
            GLES20.glGenTextures(1, textureIds, 0);
            if (textureIds[0] == 0) {
                return;
            }
            textureId = textureIds[0];
            //绑定纹理
            GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);
            //环绕（超出纹理坐标范围）  （s==x t==y GL_REPEAT 重复）
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_REPEAT);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_REPEAT);
            //过滤（纹理像素映射到坐标点）  （缩小、放大：GL_LINEAR线性）
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
            GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);

            Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), R.mipmap.bg);

            if (bitmap == null) {
                return;
            }
            //设置纹理为2d图片
            GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
        }
    }

    public void draw() {
        //使用程序
        GLES20.glUseProgram(program);
        GLES20.glEnableVertexAttribArray(avPosition);
        GLES20.glEnableVertexAttribArray(afPosition);
        //设置顶点位置值
        GLES20.glVertexAttribPointer(avPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer);
        //设置纹理位置值
        GLES20.glVertexAttribPointer(afPosition, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, textureBuffer);
        //绘制 GLES20.GL_TRIANGLE_STRIP:复用坐标
        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, vertexCount);
        GLES20.glDisableVertexAttribArray(avPosition);
        GLES20.glDisableVertexAttribArray(afPosition);
    }
}

ShaderUtil.java

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import android.content.Context;
import android.opengl.GLES20;
import android.util.Log;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ShaderUtil {
    private static final String TAG = "ShaderUtil";


    public static String readRawTxt(Context context, int rawId) {
        InputStream inputStream = context.getResources().openRawResource(rawId);
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        StringBuffer sb = new StringBuffer();
        String line;
        try {
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return sb.toString();
    }

    public static int loadShader(int shaderType, String source) {
        // create a vertex shader type (GLES20.GL_VERTEX_SHADER)
        // or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
        int shader = GLES20.glCreateShader(shaderType);
        if (shader != 0) {
            //添加代码到shader
            GLES20.glShaderSource(shader, source);
            //编译shader
            GLES20.glCompileShader(shader);
            int[] compile = new int[1];
            //检测是否编译成功
            GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compile, 0);
            if (compile[0] != GLES20.GL_TRUE) {
                Log.d(TAG, "shader compile error");
                GLES20.glDeleteShader(shader);
                shader = 0;
            }
        }
        return shader;
    }

    public static int createProgram(String vertexSource, String fragmentSource) {
        //获取vertex shader
        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
        if (vertexShader == 0) {
            return 0;
        }
        //获取fragment shader
        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
        if (fragmentShader == 0) {
            return 0;
        }
        //创建一个空的渲染程序
        int program = GLES20.glCreateProgram();
        if (program != 0) {
            //添加vertexShader到渲染程序
            GLES20.glAttachShader(program, vertexShader);
            //添加fragmentShader到渲染程序
            GLES20.glAttachShader(program, fragmentShader);
            //关联为可执行渲染程序
            GLES20.glLinkProgram(program);
            int[] linsStatus = new int[1];
            //检测是否关联成功
            GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linsStatus, 0);
            if (linsStatus[0] != GLES20.GL_TRUE) {
                Log.d(TAG, "link program error");
                GLES20.glDeleteProgram(program);
                program = 0;
            }
        }
        return program;

    }

}

  1. Render书写
    MyRender.java

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    import android.content.Context;
    import android.opengl.GLES20;
    import android.opengl.GLSurfaceView;

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

    public class MyRender implements GLSurfaceView.Renderer {

        private Context context;

        private BitmapTexture bitmapTexture;

        public MyRender(Context context) {
            this.context = context;
        }

        @Override
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
            bitmapTexture = new BitmapTexture(context);
            bitmapTexture.onSurfaceCreated();
        }

        @Override
        public void onSurfaceChanged(GL10 gl, int width, int height) {
            //宽高
            GLES20.glViewport(0, 0, width, height);
        }

        @Override
        public void onDrawFrame(GL10 gl) {
            //清空颜色
            GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
            //设置背景颜色
    //        GLES20.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

            bitmapTexture.draw();
        }
    }

  2. GLSurfaceView引用Renderer

MyGLSurfaceView.java

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import android.content.Context;
import android.opengl.GLSurfaceView;
import android.util.AttributeSet;

public class MyGLSurfaceView extends GLSurfaceView{

    public MyGLSurfaceView(Context context) {
        this(context, null);
    }

    public MyGLSurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setEGLContextClientVersion(2);
        setRenderer(new MyRender(context));
    }
}

-------------The End-------------