应该建立一个vertex shader文件和一个pixel shader文件，分别命名为shader.vsh和shader.fsh。
shader.vsh:
attribute vec3 position; //入参，主程序会将数值传入 void main() { gl_Position = vec4(position,1); //顶点经过投影变换变换后的位置 }
shader.fsh:
void main() { gl_FragColor = vec4(0.5,0.5,0.5,1); //顶点的颜色 }
ViewController.m中的代码如下：
// // ViewController.m // OpenGL学习Demo // // Created by 孙建飞 on 16/7/9. // Copyright © 2016年 sjf. All rights reserved. // #import "ViewController.h" #import <OpenGLES/ES3/gl.h> #import <OpenGLES/ES3/glext.h> @interface ViewController () { EAGLContext *context; //EAGLContent是苹果在ios平台下实现的opengles渲染层，用于渲染结果在目标surface上的更新。 GLuint program;//？？？？？？？？ GLuint vertexID; // GLvoid *vec; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; //三点的坐标： GLKVector3 vec[3]={ {0.5,0.5,0}, {-0.5,-0.5,0}, {0.5,-0.5,0}, }; //初始化EAGLContext时指定ES版本号OPenGLES3 context=[[EAGLContext alloc]initWithAPI:kEAGLRenderingAPIOpenGLES3]; if (!context) { NSLog(@"failed to create ES context !") ; } // GLKView *view=(GLKView *)self.view; view.context=context; view.drawableDepthFormat=GLKViewDrawableDepthFormat24; [EAGLContext setCurrentContext:context]; glEnable(GL_DEPTH_TEST);//开启深度测试，就是让离你近的物体可以遮挡离你远的物体 glClearColor(0.1, 0.2, 0.3, 1); //设置surface的清除颜色，也就是渲染到屏幕上的背景色。 // [self loadShaders]; glEnable(GL_DEPTH_TEST); glClearColor(0.1, 0.2, 0.3, 1); // glGenVertexArrays(<#GLsizei n#>, <#GLuint *arrays#>) glGenVertexArrays(1, &vertexID);//生成一个vao对象 glBindVertexArray(vertexID); //绑定vao GLuint bufferID; glGenBuffers(1, &bufferID); //生成vbo // glBindBuffer(GL_ARRAY_BUFFER, bufferID); //绑定 // glBufferData(<#GLenum target#>, <#GLsizeiptr size#>, <#const GLvoid *data#>, <#GLenum usage#>) glBufferData(GL_ARRAY_BUFFER, sizeof(vec), vec, GL_STATIC_DRAW); //填充缓冲对象 GLuint loc=glGetAttribLocation(program, "position"); //获得shader里position变量的索引 glEnableVertexAttribArray(loc); //启用这个索引 glVertexAttribPointer(loc, 3, GL_FLOAT, GL_FALSE, sizeof(GLKVector3), 0); //设置这个索引需要填充的内容 glBindVertexArray(0); //释放vao glBindBuffer(GL_ARRAY_BUFFER, 0); //释放vbo } //隐藏状态栏 - (BOOL)prefersStatusBarHidden { return YES; } // -(void)glkView:(GLKView *)view drawInRect:(CGRect)rect { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //清除surface内容，恢复至初始状态。 glBindVertexArray(vertexID); glUseProgram(program); //使用shader glDrawArrays(GL_TRIANGLES, 0, 3); //绘制三角形 glBindVertexArray(0); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0); } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } /***************************加载shader***************************/ - (BOOL)loadShaders { GLuint vertShader, fragShader; NSString *vertShaderPathname, *fragShaderPathname; // Create shader program. program = glCreateProgram(); // Create and compile vertex shader. vertShaderPathname = [[NSBundle mainBundle] pathForResource:@"shader" ofType:@"vsh"]; if (![self compileShader:&vertShader type:GL_VERTEX_SHADER file:vertShaderPathname]) { NSLog(@"Failed to compile vertex shader"); return NO; } // Create and compile fragment shader. fragShaderPathname = [[NSBundle mainBundle] pathForResource:@"shader" ofType:@"fsh"]; if (![self compileShader:&fragShader type:GL_FRAGMENT_SHADER file:fragShaderPathname]) { NSLog(@"Failed to compile fragment shader"); return NO; } // Attach vertex shader to program. glAttachShader(program, vertShader); // Attach fragment shader to program. glAttachShader(program, fragShader); // Link program. if (![self linkProgram:program]) { NSLog(@"Failed to link program: %d", program); if (vertShader) { glDeleteShader(vertShader); vertShader = 0; } if (fragShader) { glDeleteShader(fragShader); fragShader = 0; } if (program) { glDeleteProgram(program); program = 0; } return NO; } // Release vertex and fragment shaders. if (vertShader) { glDetachShader(program, vertShader); glDeleteShader(vertShader); } if (fragShader) { glDetachShader(program, fragShader); glDeleteShader(fragShader); } return YES; } - (BOOL)compileShader:(GLuint *)shader type:(GLenum)type file:(NSString *)file { GLint status; const GLchar *source; source = (GLchar *)[[NSString stringWithContentsOfFile:file encoding:NSUTF8StringEncoding error:nil] UTF8String]; if (!source) { NSLog(@"Failed to load vertex shader"); return NO; } *shader = glCreateShader(type); glShaderSource(*shader, 1, &source, NULL); glCompileShader(*shader); #if defined(DEBUG) GLint logLength; glGetShaderiv(*shader, GL_INFO_LOG_LENGTH, &logLength); if (logLength > 0) { GLchar *log = (GLchar *)malloc(logLength); glGetShaderInfoLog(*shader, logLength, &logLength, log); NSLog(@"Shader compile log: %s", log); free(log); } #endif glGetShaderiv(*shader, GL_COMPILE_STATUS, &status); if (status == 0) { glDeleteShader(*shader); return NO; } return YES; } - (BOOL)linkProgram:(GLuint)prog { GLint status; glLinkProgram(prog); #if defined(DEBUG) GLint logLength; glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &logLength); if (logLength > 0) { GLchar *log = (GLchar *)malloc(logLength); glGetProgramInfoLog(prog, logLength, &logLength, log); NSLog(@"Program link log: %s", log); free(log); } #endif glGetProgramiv(prog, GL_LINK_STATUS, &status); if (status == 0) { return NO; } return YES; } - (BOOL)validateProgram:(GLuint)prog { GLint logLength, status; glValidateProgram(prog); glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &logLength); if (logLength > 0) { GLchar *log = (GLchar *)malloc(logLength); glGetProgramInfoLog(prog, logLength, &logLength, log); NSLog(@"Program validate log: %s", log); free(log); } glGetProgramiv(prog, GL_VALIDATE_STATUS, &status); if (status == 0) { return NO; } return YES; } @end
运行后得到如下：
参考文献：