cocoa - 最简单、简约、opengl 3.2 cocoa项目

Question

我多年来一直使用旧版 openGL 和 cocoa，但现在我正在努力过渡到 openGL 3.2。互联网上有几个例子，但它们都太复杂了(许多甚至在 XCode 5.1 下不再编译)。有人可以编写一个最简单、简约、最小的 cocoa 代码示例，只是为了将读取三角形绘制到 NSOpenGLView 吗？ (没有花哨的着色器，没有显示回调，代码行越少越好)。

Answer 1

这是基于https://github.com/beelsebob/Cocoa-GL-Tutorial中的代码的答案我更改了这些内容: (1) openGL 上下文是在自定义 NSOpenGLView 中创建的，而不是直接附加到窗口。 (2) 我将所有初始化都放在一个函数中。 (3)我把错误验证码全部删除了。这不是你应该为产品做的事情，但我发现它更容易理解代码并且更少困惑......(查看 Cocoa-GL-Tutorial 以进行正确的错误处理)。

步骤(使用 Xcode 5.1 测试):

1. 创建一个新的 cocoa 应用程序
2. 将自定义 View 添加到界面构建器中的应用窗口
3. 添加一个 Objective-C 类，子类化 NSOpenGLView，我将其命名为 MyOpenGLView
4. 在界面构建器中，选择 CustomView，选择 Identity Inspector(右上角的图标之一)，然后在 Custom Class 中选择 MyOpenGLView
5. 现在，这是 MyOpenGLView.h 的代码:

    #import <Cocoa/Cocoa.h>    #import <OpenGL/OpenGL.h>    #import <OpenGL/gl3.h>    @interface MyOpenGLView : NSOpenGLView    {        GLuint shaderProgram;        GLuint vertexArrayObject;        GLuint vertexBuffer;        GLint positionUniform;        GLint colourAttribute;        GLint positionAttribute;    }    @end

这是MyOpenGLView.m的代码:

    #import "MyOpenGLView.h"    @implementation MyOpenGLView    - (id)initWithFrame:(NSRect)frame    {        // 1. Create a context with opengl pixel format        NSOpenGLPixelFormatAttribute pixelFormatAttributes[] =        {            NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core,            NSOpenGLPFAColorSize    , 24                           ,            NSOpenGLPFAAlphaSize    , 8                            ,            NSOpenGLPFADoubleBuffer ,            NSOpenGLPFAAccelerated  ,            NSOpenGLPFANoRecovery   ,            0        };        NSOpenGLPixelFormat *pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:pixelFormatAttributes];        self = [super initWithFrame:frame pixelFormat:pixelFormat];        // 2. Make the context current        [[self openGLContext] makeCurrentContext];        // 3. Define and compile vertex and fragment shaders        GLuint  vs;        GLuint  fs;        const char    *vss="#version 150\n\        uniform vec2 p;\        in vec4 position;\        in vec4 colour;\        out vec4 colourV;\        void main (void)\        {\        colourV = colour;\        gl_Position = vec4(p, 0.0, 0.0) + position;\        }";        const char    *fss="#version 150\n\        in vec4 colourV;\        out vec4 fragColour;\        void main(void)\        {\        fragColour = colourV;\        }";        vs = glCreateShader(GL_VERTEX_SHADER);        glShaderSource(vs, 1, &vss, NULL);        glCompileShader(vs);        fs = glCreateShader(GL_FRAGMENT_SHADER);        glShaderSource(fs, 1, &fss, NULL);        glCompileShader(fs);        printf("vs: %i, fs: %i\n",vs,fs);        // 4. Attach the shaders        shaderProgram = glCreateProgram();        glAttachShader(shaderProgram, vs);        glAttachShader(shaderProgram, fs);        glBindFragDataLocation(shaderProgram, 0, "fragColour");        glLinkProgram(shaderProgram);        // 5. Get pointers to uniforms and attributes        positionUniform = glGetUniformLocation(shaderProgram, "p");        colourAttribute = glGetAttribLocation(shaderProgram, "colour");        positionAttribute = glGetAttribLocation(shaderProgram, "position");        glDeleteShader(vs);        glDeleteShader(fs);        printf("positionUniform: %i, colourAttribute: %i, positionAttribute: %i\n",positionUniform,colourAttribute,positionAttribute);        // 6. Upload vertices (1st four values in a row) and colours (following four values)        GLfloat vertexData[]= { -0.5,-0.5,0.0,1.0,   1.0,0.0,0.0,1.0,                                -0.5, 0.5,0.0,1.0,   0.0,1.0,0.0,1.0,                                 0.5, 0.5,0.0,1.0,   0.0,0.0,1.0,1.0,                                 0.5,-0.5,0.0,1.0,   1.0,1.0,1.0,1.0};        glGenVertexArrays(1, &vertexArrayObject);        glBindVertexArray(vertexArrayObject);        glGenBuffers(1, &vertexBuffer);        glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);        glBufferData(GL_ARRAY_BUFFER, 4*8*sizeof(GLfloat), vertexData, GL_STATIC_DRAW);        glEnableVertexAttribArray((GLuint)positionAttribute);        glEnableVertexAttribArray((GLuint)colourAttribute  );        glVertexAttribPointer((GLuint)positionAttribute, 4, GL_FLOAT, GL_FALSE, 8*sizeof(GLfloat), 0);        glVertexAttribPointer((GLuint)colourAttribute  , 4, GL_FLOAT, GL_FALSE, 8*sizeof(GLfloat), (char*)0+4*sizeof(GLfloat));        return self;    }    - (void)drawRect:(NSRect)dirtyRect    {        [super drawRect:dirtyRect];        glClearColor(0.0, 0.0, 0.0, 1.0);        glClear(GL_COLOR_BUFFER_BIT);        glUseProgram(shaderProgram);        GLfloat p[]={0,0};        glUniform2fv(positionUniform, 1, (const GLfloat *)&p);        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);        [[self openGLContext] flushBuffer];    }    @end