多年来，我一直在使用可可的传统 openGL，但我现在正在努力过渡到 openGL 3.2。互联网上有几个例子，但它们都太复杂了（很多甚至不再在 XCode 5.1 下编译）。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 displayCallbacks，代码行越少越好）。
【问题讨论】：
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中。 (2) 我在一个函数中完成所有初始化。 (3) 我删除了所有的错误验证码。这不是你应该为产品做的事情，但我发现更容易理解代码而不是混乱......（查看 Cocoa-GL-Tutorial 以获得正确的错误处理）。
步骤（用 Xcode 5.1 测试）：
MyOpenGLView.h 的代码：这是MyOpenGLView.m的代码：
【讨论】：
https://stackoverflow.com/a/22502999/4946861
在 xcode 6.3.2 中，我得到了替换
后运行的示例(id)initWithFrame:(NSRect)frame
与(void)awakeFromNib
替换
self = [super initWithFrame:frame pixelFormat:pixelFormat];
与super.pixelFormat=pixelFormat;
和删除return self;
或详细写出来：
#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
【讨论】：