OpenGLES（七）-GLSL案例：纹理颜色混合OpenGLES（七）-GLSL案例：纹理颜色混合

attribute vec4 position;
attribute vec4 positionColor;
attribute vec2 textureCoord;

varying lowp vec2 varyingTexCoord;
varying vec4 varyingColor;

void main() {
    varyingColor = positionColor;
    varyingTexCoord = textureCoord;
    gl_Position = position;
}

precision highp float;
varying lowp vec2 varyingTexCoord;
varying vec4 varyingColor;
uniform sampler2D colorMap;
uniform lowp float alpha;

void main() {
    vec4 vTexColor = texture2D(colorMap, varyingTexCoord);
    vec4 vColor = varyingColor;
    gl_FragColor = vTexColor * (1.0 - alpha) + vColor * alpha;
}

    //初始化s顶点缓存区
    GLuint buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, sizeof(vertex), &vertex, GL_DYNAMIC_DRAW);
    //将顶点数据传入着色器
    GLuint position = glGetAttribLocation(self.myProgram, "position");
    glEnableVertexAttribArray(position);
    glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat*)NULL + 0);
    //将纹理坐标传入着色器
    GLuint texCoord = glGetAttribLocation(self.myProgram, "textureCoord");
    glEnableVertexAttribArray(texCoord);
    glVertexAttribPointer(texCoord, 2, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat*)NULL + 3);
    //将颜色传入着色器
    GLuint positionColor = glGetAttribLocation(self.myProgram, "positionColor");
    glEnableVertexAttribArray(positionColor);
    glVertexAttribPointer(positionColor, 3, GL_FLOAT, GL_FALSE, sizeof(GLfloat) * 8, (GLfloat*)NULL + 5);

    //加载纹理并传入片元着色器
    GLuint texture = [self loadImage];
    glActiveTexture(texture);
    glUniform1i(glGetUniformLocation(self.myProgram, "colorMap"), 0);
    glUniform1f(glGetUniformLocation(self.myProgram, "alpha"), 0.3);
    //使用索引绘图
    glDrawElements(GL_TRIANGLES, sizeof(indices) / sizeof(indices[0]), GL_UNSIGNED_INT, indices);
    
    [self.myContent presentRenderbuffer:GL_RENDERBUFFER];