OpenGL之图片色彩处理（三）

阳光穿透心脏的1/2处 2022-05-21 05:29 342阅读 0赞

一、OpenGL图片绘制的一般步骤：

1、编写顶点着色器和片元着色器；

2、编写需要绘制的图形类，包括：加载着色器脚本内容，加载图片数据，图片绘制；

3、配置绘制环境，绘制图片。

二、具体如下：

1、 编写顶点着色器程序（glsl语言）：

attribute vec4 vPosition;
    attribute vec2 vCoordinate;//纹理数据
    uniform mat4 vMatrix;
    //给片元传递数据（纹理，变换前的顶点，变换后的顶点）
    varying vec2 aCoordinate;
    varying vec4 aPos;
    varying vec4 gPosition;
    
    void main(){
        gl_Position=vMatrix*vPosition;
        aPos=vPosition;
        aCoordinate=vCoordinate;
        gPosition=vMatrix*vPosition;
    }

2、 编写片元着色器程序（glsl语言）：

precision mediump float;
    
    uniform sampler2D vTexture;
    uniform int vChangeType;
    uniform vec3 vChangeColor;
    uniform int vIsHalf;
    uniform float uXY;
    
    //给片元传递的数据（纹理数据，变换前顶点，变换后顶点）
    varying vec2 aCoordinate;
    varying vec4 aPos;
    varying vec4 gPosition;
    
    //修改颜色（防止颜色值超过一）
    void modifyColor(vec4 color){
         color.r=max(min(color.r,1.0),0.0);
         color.g=max(min(color.g,1.0),0.0);
         color.b=max(min(color.b,1.0),0.0);
         color.a=max(min(color.a,1.0),0.0);
     }
    void main() {
       vec4 nColor=texture2D(vTexture,aCoordinate);
       if(aPos.x>0.0 || vIsHalf == 0){
            if(vChangeType==1){
                //浮点算法     Gray=R * 0.3+G * 0.59+B * 0.114
                float gray=(nColor.r*0.3+nColor.g*0.59+nColor.b*0.114);
                gl_FragColor=vec4(gray,gray,gray,nColor.a);
            }else if(vChangeType==2){
                vec4 colorWarm=nColor+vec4(0.1,0.1,0.0,0.0);
                modifyColor(colorWarm);
                gl_FragColor=colorWarm;
            }else if(vChangeType==3){
                vec4 colorCold=nColor+vec4(0.0,0.0,0.1,0.0);
                modifyColor(colorCold);
                gl_FragColor=colorCold;
            }else if(vChangeType==4){
                vec2 texSize = vec2(1500.0f,1500.0f);
                vec2 upTex=vec2(aCoordinate.x-1.0/texSize.x,aCoordinate.y-1.0/texSize.y);
                vec4 newTex=texture2D(vTexture,upTex);
                vec4 delTex=nColor-newTex;
                gl_FragColor=delTex;
            }else if(vChangeType==5){
                gl_FragColor=texture2D(vTexture,vec2(1.0-aCoordinate.x,1.0-aCoordinate.y));
            }else{
                gl_FragColor=nColor;
            }
       }else{
            gl_FragColor=nColor;
       }
    }

3、编写绘制图像类（java）

public class Image extends ShaderUtils {
    
        private FloatBuffer bPos;
        private FloatBuffer bCoord;
    
        //图片四个角的坐标
        public final float[] sPos = {
                -1.0f, 1.0f,
                -1.0f, -1.0f,
                1.0f, 1.0f,
                1.0f, -1.0f
    
        };
        //图片四个角的纹理坐标
        public final float[] sCoord = {
                0.0f, 0.0f,
                0.0f, 1.0f,
                1.0f, 0.0f,
                1.0f, 1.0f,
        };
    
        private int mProgram;
        private int glHPosition;
        private int glHTexture;
        private int glHCoordinate;
        public int glHMatrix;
        private int hIsHalf;
        public int glHUxy;
        private int hChangeType;
        private int hChangeColor;
    
        public Image(GLSurfaceView mView) {
            initData();
            initShader(mView);
        }
    
        private void initShader(GLSurfaceView mv) {
            /*//加载顶点着色器的脚本内容
            String mVertexShader = loadFromAssetsFile("filter/vertex.glsl", mv.getResources());
            //加载片元着色器的脚本内容
            String mFragmentShader = loadFromAssetsFile("filter/fragment.glsl", mv.getResources());
            mProgram=createProgram(mVertexShader,mFragmentShader);*/
            mProgram=createProgram(mv.getResources(),"filter/vertex.glsl","filter/fragment.glsl");
            glHPosition= GLES20.glGetAttribLocation(mProgram,"vPosition");
            glHCoordinate=GLES20.glGetAttribLocation(mProgram,"vCoordinate");
            glHTexture=GLES20.glGetUniformLocation(mProgram,"vTexture");
            glHMatrix=GLES20.glGetUniformLocation(mProgram,"vMatrix");
            hIsHalf=GLES20.glGetUniformLocation(mProgram,"vIsHalf");
            glHUxy=GLES20.glGetUniformLocation(mProgram,"uXY");
            hChangeType=GLES20.glGetUniformLocation(mProgram,"vChangeType");
            hChangeColor=GLES20.glGetUniformLocation(mProgram,"vChangeColor");
        }
    
        private void initData() {
            bPos = getFloatBuffer(sPos);
            bCoord = getFloatBuffer(sCoord);
        }
    
        private int count=1;
        public float[][] images = new float[][]{
                {
      0.0f, 0.0f, 0.0f}//原图
                , {
      0.299f, 0.587f, 0.114f}//灰度
                , {
      0.1f, 0.1f, 0.0f}//暖色调
                , {
      0.0f, 0.0f, 0.1f}//冷色调
                , {
      0.2125f, 0.7154f, 0.0721f}//浮雕
                , {
      0.0f, 0.0f, 0.0f}
                , {
      0.0f, 0.0f, 0.0f}
                , {
      0.0f, 0.0f, 0.0f}
        };
        public void drawSelf(int textureId) {
            GLES20.glUseProgram(mProgram);
            GLES20.glUniform1i(hChangeType,count);
            GLES20.glUniform3fv(hChangeColor,1,images[count],0);
            GLES20.glUniform1i(hIsHalf,0);
            GLES20.glEnableVertexAttribArray(glHPosition);
            GLES20.glEnableVertexAttribArray(glHCoordinate);
            GLES20.glUniform1i(glHTexture,0);
            GLES20.glVertexAttribPointer(glHPosition,2,GLES20.GL_FLOAT,false,0,bPos);
            GLES20.glVertexAttribPointer(glHCoordinate,2,GLES20.GL_FLOAT,false,0,bCoord);
            GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP,0,4);
        }
    }

这个里面的ShaderUtils是编写好的工具类，作用是加载着色器程序。

4、编写渲染类SGLView（java）

public class SGLView extends GLSurfaceView implements GLSurfaceView.Renderer{
    
        private Image image;
        private int textureId;
        private Bitmap mBitmap;
        private float uXY;
    
        private float[] mViewMatrix = new float[16];
        private float[] mProjectMatrix = new float[16];
        private float[] mMVPMatrix = new float[16];
    
        public SGLView(Context context) {
            super(context);
            init();
        }
    
        private void init() {
            setEGLContextClientVersion(2);
            setRenderer(this);
            setRenderMode(RENDERMODE_CONTINUOUSLY);
        }
    
        @Override
        public void onSurfaceCreated(GL10 gl, EGLConfig config) {
            GLES20.glClearColor(1.0f,1.0f,1.0f,1.0f);
            GLES20.glEnable(GLES20.GL_TEXTURE_2D);
            image = new Image(this);
            textureId = createTexture();
        }
    
        //创建纹理
        private int createTexture() {
            mBitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.girl);
            int[] texture = new int[1];
            if(mBitmap != null && !mBitmap.isRecycled()){
                //生成纹理
                GLES20.glGenTextures(1,texture,0);
                GLES20.glBindTexture(GLES20.GL_TEXTURE_2D,texture[0]);
                GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_MIN_FILTER,GLES20.GL_NEAREST);
                GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_MAG_FILTER,GLES20.GL_LINEAR);
    
                GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_WRAP_S,GLES20.GL_CLAMP_TO_EDGE);
                GLES20.glTexParameterf(GLES20.GL_TEXTURE_2D,GLES20.GL_TEXTURE_WRAP_T,GLES20.GL_CLAMP_TO_EDGE);
    
                //根据以上参数，生成纹理
                GLUtils.texImage2D(GLES20.GL_TEXTURE_2D,0,mBitmap,0);
    
                return texture[0];
            }
            return 0;
        }
    
        @Override
        public void onSurfaceChanged(GL10 gl, int width, int height) {
            GLES20.glViewport(0,0,width,height);
    
            int w = mBitmap.getWidth();
            int h = mBitmap.getHeight();
            float swh = (float)w/h;
            float sWH = (float)width/height;
            uXY = sWH;
            if(sWH > swh){
                Matrix.orthoM(mProjectMatrix,0,-1,1,-swh/sWH,swh/sWH,3,5);
            }else{
                Matrix.orthoM(mProjectMatrix,0,-1,1,-sWH/swh,sWH/swh,3,5);
            }
            //设置相机的位置
            Matrix.setLookAtM(mViewMatrix,0,0,0,5.0f,0,0,0,0,1.0f,0);
            //计算变换矩阵
            Matrix.multiplyMM(mMVPMatrix,0,mProjectMatrix,0,mViewMatrix,0);
        }
    
        @Override
        public void onDrawFrame(GL10 gl) {
            GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT|GLES20.GL_DEPTH_BUFFER_BIT);
    
            GLES20.glUniform1f(image.glHUxy, uXY);
            GLES20.glUniformMatrix4fv(image.glHMatrix, 1, false, mMVPMatrix, 0);
            image.drawSelf(textureId);
        }
    }

5、在Activity中加载SGLView

public class Main2Activity extends AppCompatActivity {
    
      
        private SGLView sView;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            sView = new SGLView(this);
            setContentView(sView);
        }
    
        @Override
        protected void onResume() {
            super.onResume();
            sView.onResume();
        }
    
        @Override
        protected void onPause() {
            super.onPause();
            sView.onPause();
        }
    }