OpenGL播放yuv视频

//data指向yuv420p数据
- (void)playVideoData:(void *)data
{
[EAGLContext setCurrentContext:_glContext];
if (!_textureY)
{
glGenTextures(1, &_textureY);
glGenTextures(1, &_textureU);
glGenTextures(1, &_textureV);
}
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, _textureY);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED_EXT, _videoW, _videoH, 0, GL_RED_EXT, GL_UNSIGNED_BYTE, data);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);


glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, _textureU);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED_EXT, _videoW/2, _videoH/2, 0, GL_RED_EXT, GL_UNSIGNED_BYTE, data + _videoW * _videoH);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, _textureV);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED_EXT, _videoW/2, _videoH/2, 0, GL_RED_EXT, GL_UNSIGNED_BYTE, data + _videoW * _videoH * 5 / 4);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

[self render];
}

- (void)render
{
[EAGLContext setCurrentContext:_glContext];
glViewport(0, 0, 320, 320);
glClearColor(0.0, 0.6, 0.0, 1.0);

static c*****t GLfloat squareVertices[] = {
-1.0f, -1.0f,
1.0f, -1.0f,
-1.0f,1.0f,
1.0f,1.0f,
};

static c*****t GLfloat coordVertices[] = {
0.0f, 1.0f,
1.0f, 1.0f,
0.0f,0.0f,
1.0f,0.0f,
};
//GLuint vertices;
//glGenBuffers(1, &vertices);
//glBindBuffer(GL_ARRAY_BUFFER, vertices);
//glBufferData(GL_ARRAY_BUFFER, sizeof(squareVertices), squareVertices, GL_STATIC_DRAW);

glClear(GL_COLOR_BUFFER_BIT);

glUseProgram(_program);

// Update uniform value
//glUniform1f(uniforms[UNIFORM_TRANSLATE], 0.0f);
GLuint textureUniformY = glGetUniformLocation(_program, "SamplerY");
GLuint textureUniformU = glGetUniformLocation(_program, "SamplerU");
GLuint textureUniformV = glGetUniformLocation(_program, "SamplerV");

// Update attribute values
glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, squareVertices);
glEnableVertexAttribArray(ATTRIB_VERTEX);

glVertexAttribPointer(ATTRIB_TEXTURE, 2, GL_FLOAT, 0, 0, coordVertices);
glEnableVertexAttribArray(ATTRIB_TEXTURE);

glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, _textureY);
glUniform1i(textureUniformY, 0);

glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, _textureU);
glUniform1i(textureUniformU, 1);

glActiveTexture(GL_TEXTURE2);
glBindTexture(GL_TEXTURE_2D, _textureV);
glUniform1i(textureUniformV, 2);

// Draw
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

//glFlush();
[_glContext presentRenderbuffer:GL_RENDERBUFFER];
}

//Shader.vsh
attribute vec4 position; // 1
//uniform float translate;
attribute vec2 TexCoordIn; // New
varying vec2 TexCoordOut; // New

void main(void)
{
gl_Position = position; // 6
TexCoordOut = TexCoordIn;
}

//Shader.fsh
varying lowp vec2 TexCoordOut;

uniform sampler2D SamplerY;
uniform sampler2D SamplerU;
uniform sampler2D SamplerV;

void main(void)
{
mediump vec3 yuv;
lowp vec3 rgb;

yuv.x = texture2D(SamplerY, TexCoordOut).r;
yuv.y = texture2D(SamplerU, TexCoordOut).r - 0.5;
yuv.z = texture2D(SamplerV, TexCoordOut).r - 0.5;

rgb = mat3( 1, 1, 1,
0, -0.39465,2.03211,
1.13983, -0.58060,0) * yuv;

gl_FragColor = vec4(rgb, 1);

}