Android OpenGL ES基本用法（11），简单滤镜操作

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目录

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加入简单的滤镜操作

fragment_shader1.glsl

precision mediump float;
varying vec2 ft_Position;
uniform sampler2D sTexture;
void main() {
    gl_FragColor = vec4(vec3(1.0 - texture2D(sTexture, ft_Position)), 1.0);
}

fragment_shader2.glsl

precision mediump float;
varying vec2 ft_Position;
uniform sampler2D sTexture;
void main() {
    lowp vec4 textureColor = texture2D(sTexture, ft_Position);
     float gray = textureColor.r * 0.2125 + textureColor.g * 0.7154 + textureColor.b * 0.0721;
     gl_FragColor = vec4(gray, gray, gray, textureColor.w);
}

fragment_shader3.glsl

precision mediump float;
varying vec2 ft_Position;
uniform sampler2D sTexture;
void main() {
    lowp vec4 textureColor = texture2D(sTexture, ft_Position);
    gl_FragColor = vec4((textureColor.rgb + vec3(-0.5f)), textureColor.w);
}

读取shader的时候，读取各自对应的

package com.example.opengl.eglpic;

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

import com.example.opengl.R;
import com.example.opengl.egl.MyGlSurfaceView;
import com.example.opengl.egl.ShaderUtil;

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

public class PicRenderMulti implements MyGlSurfaceView.EGLRender {

    private Context context;

    private float[] vertexData = {
            -1f, -1f,
            1f, -1f,
            -1f, 1f,
            1f, 1f
    };
    private FloatBuffer vertexBuffer;

    private float[] fragmentData = {
            0f, 1f,
            1f, 1f,
            0f, 0f,
            1f, 0f
    };
    private FloatBuffer fragmentBuffer;

    private int program;
    private int vPosition;
    private int fPosition;

    private int sampler;

    private int vboId;

    private int textureId;
    private int curIndex;

    public void setTextureId(int textureId, int curIndex) {
        this.textureId = textureId;
        this.curIndex = curIndex;
    }

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

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

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

    @Override
    public void onSurfaceCreated() {
        String vertexSource = ShaderUtil.readRawTxt(context, R.raw.vertex_shader);
        String fragmentSource;
        switch (curIndex) {
            case 0:
                fragmentSource = ShaderUtil.readRawTxt(context, R.raw.fragment_shader1);
                break;
            case 1:
                fragmentSource = ShaderUtil.readRawTxt(context, R.raw.fragment_shader2);
                break;
            case 2:
                fragmentSource = ShaderUtil.readRawTxt(context, R.raw.fragment_shader3);
                break;
            default:
                fragmentSource = ShaderUtil.readRawTxt(context, R.raw.fragment_shader);
        }
        program = ShaderUtil.createProgram(vertexSource, fragmentSource);

        vPosition = GLES20.glGetAttribLocation(program, "v_Position");
        fPosition = GLES20.glGetAttribLocation(program, "f_Position");
        sampler = GLES20.glGetUniformLocation(program, "sTexture");

        int[] vbos = new int[1];
        GLES20.glGenBuffers(1, vbos, 0);
        vboId = vbos[0];

        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);
        GLES20.glBufferData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4 + fragmentData.length * 4, null, GLES20.GL_STATIC_DRAW);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, 0, vertexData.length * 4, vertexBuffer);
        GLES20.glBufferSubData(GLES20.GL_ARRAY_BUFFER, vertexData.length * 4, fragmentData.length * 4, fragmentBuffer);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }

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

    @Override
    public void onDrawFrame() {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
        GLES20.glClearColor(1f, 0f, 0f, 1f);

        GLES20.glUseProgram(program);

        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureId);


        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, vboId);

        GLES20.glEnableVertexAttribArray(vPosition);
        GLES20.glVertexAttribPointer(vPosition, 2, GLES20.GL_FLOAT, false, 8,
                0);

        GLES20.glEnableVertexAttribArray(fPosition);
        GLES20.glVertexAttribPointer(fPosition, 2, GLES20.GL_FLOAT, false, 8,
                vertexData.length * 4);

        GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);

        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0);
        GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
    }
}