最简单、简约、opengl 3.2 cocoa项目

我已经使用旧版 openGL 和 cocoa 多年了，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、最小的可可代码示例，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）。

这是基于中代码的答案https://github.com/beelsebob/Cocoa-GL-Tutorial https://github.com/beelsebob/Cocoa-GL-Tutorial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，但我发现更容易理解代码，并且更少的混乱......（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. 制作新的可可应用程序
2. 将自定义视图添加到界面生成器中的应用程序窗口
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，这是代码MyOpenGLView.h:

    #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

  

这是代码MyOpenGLView.m:

    #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