openGL es2.0 创建可移动的纹理平面-蒲公英云

openGL es2.0 创建可移动的纹理平面

一、Java部分代码

package com.gzdxid.utils;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import android.opengl.GLES20;
public class DrawRectMove {
    int mProgram;
    int muMVPMatrixHandle;
    int maPositionHandle;
    int maTexCoorHandle;
    int muSpanHandle;
    FloatBuffer mVertexBuffer;
    FloatBuffer mTexCoorBuffer;
    int vCount=0;
    public DrawRectMove(float width,float height,int mProgram) {
        // TODO Auto-generated constructor stub
        initVertex(width,height);
        initShader(mProgram);
    }
    private void initVertex(float width, float height) {
        // TODO Auto-generated method stub
        vCount = 6;
        float w = width / 2;
        float h = height / 2;
        float vertices[] = new float[] { 
        -w,  h, 0,
        -w, -h, 0,
         w, -h, 0,
         w, -h, 0,
         w,  h, 0,
        -w,  h, 0,
        };
        ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length * 4);
        vbb.order(ByteOrder.nativeOrder());
        mVertexBuffer = vbb.asFloatBuffer();
        mVertexBuffer.put(vertices);
        mVertexBuffer.position(0);
        float texCoor[] = new float[] { 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0 };
        ByteBuffer cbb = ByteBuffer.allocateDirect(texCoor.length * 4);
        cbb.order(ByteOrder.nativeOrder());
        mTexCoorBuffer = cbb.asFloatBuffer();
        mTexCoorBuffer.put(texCoor);
        mTexCoorBuffer.position(0);
    }
    private void initShader(int mProgram) {
        // TODO Auto-generated method stub
        this.mProgram = mProgram;
        muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
        maPositionHandle = GLES20.glGetAttribLocation(mProgram, "aPosition");
        maTexCoorHandle = GLES20.glGetAttribLocation(mProgram, "aTexCoor");
        muSpanHandle=GLES20.glGetUniformLocation(mProgram, "uSpan");
    }
    public void drawSelf(int texId,float currStart){
        GLES20.glUseProgram(mProgram);
        GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, MatrixState.getFinalMatrix(), 0);
        GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 3*4, mVertexBuffer);
        GLES20.glVertexAttribPointer(maTexCoorHandle, 2, GLES20.GL_FLOAT, false, 2*4, mTexCoorBuffer);
        GLES20.glEnableVertexAttribArray(maPositionHandle);
        GLES20.glEnableVertexAttribArray(maTexCoorHandle);
        GLES20.glUniform1f(muSpanHandle, currStart);
        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texId);
        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vCount);
    }
}

二、定点着色器：

uniform mat4 uMVPMatrix;
attribute vec3 aPosition;
attribute vec2 aTexCoor;
varying vec2 vTextureCoord;
void main()
{
   gl_Position=uMVPMatrix*vec4(aPosition,1);
   vTextureCoord=aTexCoor;
}

三、片源着色器：
precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D sTexture;
uniform float uSpan;
void main()
{
vec2 st_Result=vec2(0,0);
st_Result.x=vTextureCoord.x;
st_Result.y=vTextureCoord.y+uSpan;
gl_FragColor=texture2D(sTexture,st_Result);
}

这里面是移动y轴参数，当然也可以移动x轴的。在Java代码中的drawSelf()中，currStart参数改变影响图片在指定大小平面上移动。