最简单，简约的opengl 3.2可可项目 [英] The simplest, minimalistic, opengl 3.2 cocoa project

问题描述

我已经使用了传统的openGL与可可多年，但我现在正在努力，以转换到openGL 3.2。在互联网有几个例子，但他们都太复杂（许多甚至不编译任何更多在XCode 5.1下）。有人可以写一个最简单，简约，最小的可可代码的例子，只是为NSOpenGLView绘制一个读三角形？ （无花式着色器，无displayCallbacks，代码行越少越好）。

I have used the legacy openGL with cocoa for years, but I'm now struggling to make the transition to openGL 3.2. There are several examples in the internet, but they are all too complex (and many don't even compile any more under XCode 5.1). Could someone write an example of the simplest, minimalistic, minimum cocoa code just to draw a read triangle to a NSOpenGLView? (no fancy shaders, no displayCallbacks, the fewer the code lines, the better).

推荐答案

http://stackoverflow.com/a/22502999/4946861

在xcode 6.3.2中我有一个例子运行后替换

In xcode 6.3.2 I got the example running afterreplacement of

（id）initWithFrame：（NSRect）frame

with

（void）awakeFromNib

并替换

self = [super initWithFrame：frame pixelFormat：pixelFormat];

with

super.pixelFormat = pixelFormat;

并删除

return self;

或详细写出：

#import "MyOpenGLView.h"

@implementation MyOpenGLView


- (void)awakeFromNib
{
    NSLog(@"...was here");
    // 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];

    super.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));

}


- (void)drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];

    // Drawing code here.

    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

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