OpenGL在Mac上没有绘制任何东西，Objective-C

Z时代
2024-01-10
分类：问答

我想绘制一些使用OpenGL与VAO和VBO对象的东西。要做到这一点，我只需要分类NSOpenGLView。默认情况下，使用OpenGL v2.1，所以，我放了一个PixelFormat，编写代码，并解决了所有打印错误。目前该应用运行良好，但没有任何东西在窗口绘制，即使glClearColor也没有效果。请帮助我找到并解决问题。我的操作系统是带有OpenGL v4.1的Mac v10.12。OpenGL在Mac上没有绘制任何东西，Objective-C

MyOpenGLView.m，第1部分：

#import "MyOpenGLView.h" 
#include <OpenGL/gl3.h> 
#include "error.h" 
static const char *vertexShaderSource = 
"#version 410\n" 
"in vec3 posAttr;\n" 
"in vec3 colAttr;\n" 
"out vec3 col;\n" 
"void main() {\n" 
" col = colAttr;\n" 
" gl_Position.xyz = posAttr;\n" 
" gl_Position.w = 1.0;\n" 
" col = colAttr;\n" 
"}\n"; 
static const char *fragmentShaderSource = 
"#version 410\n" 
"in vec3 col;\n" 
"out vec4 color;\n" 
"void main() {\n" 
" color.rgb = col;\n" 
" color.a = 1.0;\n" 
//" color = vec4(1,1,1,1);\n" 
"}\n"; 
// Shader properties 
GLuint m_posAttr; 
GLuint m_colAttr; 
GLuint program; 
// Arrays of positions and colors 
float fTriangle[9]; 
float fTriangleColor[9]; 
// Low-level VBOs and VBAs 
GLuint uiVBO[2]; 
GLuint uiVAO[1]; 
GLuint makeShader(GLenum type, const char *source) { 
    GLuint shader; 
    shader = glCreateShader(type); 
    GetError(); 
    glShaderSource(shader, 1, &source, NULL); 
    GetError(); 
    glCompileShader(shader); 
    GetError(); 
#if defined(DEBUG) 
    GLint logLength; 
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logLength); 
    GetError(); 
    if (logLength > 0) { 
     GLchar *log = malloc((size_t)logLength); 
     glGetShaderInfoLog(shader, logLength, &logLength, log); 
     GetError(); 
     NSLog(@"Shader compilation failed with error:\n%s", log); 
     free(log); 
    } 
#endif 
    GLint status; 
    glGetShaderiv(shader, GL_COMPILE_STATUS, &status); 
    GetError(); 
    if (0 == status) { 
     glDeleteShader(shader); 
     GetError(); 
     NSLog(@"Shader compilation failed from code!"); 
     assert(0); 
    } 
    return shader; 
}

MyOpenGLView.m，第2部分：

//// General staff 
@implementation MyOpenGLView 
- (void)awakeFromNib { 
    // Positions and colors of figures 
    fTriangle[0] = -0.4f; fTriangle[1] = 0.1f; fTriangle[2] = 0.0f; 
    fTriangle[3] = 0.4f; fTriangle[4] = 0.1f; fTriangle[5] = 0.0f; 
    fTriangle[6] = 0.0f; fTriangle[7] = 0.7f; fTriangle[8] = 0.0f; 
    fTriangleColor[0] = 1.0f; fTriangleColor[1] = 0.0f; fTriangleColor[2] = 0.0f; 
    fTriangleColor[3] = 0.0f; fTriangleColor[4] = 1.0f; fTriangleColor[5] = 0.0f; 
    fTriangleColor[6] = 0.0f; fTriangleColor[7] = 0.0f; fTriangleColor[8] = 1.0f; 
    NSOpenGLPixelFormatAttribute attrs[] = { 
     NSOpenGLPFADoubleBuffer, 
     NSOpenGLPFADepthSize, 24, 
     NSOpenGLPFAOpenGLProfile, 
     NSOpenGLProfileVersion4_1Core, 
     0 
    }; 
    NSOpenGLPixelFormat *pf = [[NSOpenGLPixelFormat alloc] initWithAttributes:attrs]; 
    if (!pf) { 
     NSLog(@"No OpenGL pixel format"); 
    } 
    NSOpenGLContext* context = [[NSOpenGLContext alloc] initWithFormat:pf shareContext:nil]; 
    [self setPixelFormat:pf]; 
    [self setOpenGLContext:context]; 
    NSLog(@"%s", glGetString(GL_VERSION)); 
    GetError(); 
    GLuint vertexShader = makeShader(GL_VERTEX_SHADER, vertexShaderSource); 
    GLuint fragmentShader = makeShader(GL_FRAGMENT_SHADER, fragmentShaderSource); 
    program = glCreateProgram(); 
    GetError(); 
    glAttachShader(program, vertexShader); 
    GetError(); 
    glAttachShader(program, fragmentShader); 
    GetError(); 
    glLinkProgram(program); 
    GetError(); 
    GLint status; 
    glGetProgramiv(program, GL_LINK_STATUS, &status); 
    GetError(); 
    if (0 == status) { 
     NSLog(@"Failed to link shader program"); 
     assert(0); 
    } 
    m_posAttr = glGetAttribLocation(program, "posAttr"); 
    GetError(); 
    m_colAttr = glGetAttribLocation(program, "colAttr"); 
    GetError(); 
    glGenVertexArrays(1, &uiVAO[0]); 
    glGenBuffers(2, &uiVBO[0]); 
    GetError(); 
} 
- (void)drawRect:(NSRect)dirtyRect { 
    [super drawRect:dirtyRect]; 
    glClearColor(0, 0, 0, 0); 
    glClear(GL_COLOR_BUFFER_BIT); 
    glUseProgram(program); 
    GetError(); 
    glBindVertexArray(uiVAO[0]); 
    GetError(); 
    glBindBuffer(GL_ARRAY_BUFFER, uiVBO[0]); 
    glBufferData(GL_ARRAY_BUFFER, 9*sizeof(float), fTriangle, GL_STATIC_DRAW); 
    glEnableVertexAttribArray(m_posAttr); 
    GetError(); 
    glVertexAttribPointer(m_posAttr, 3, GL_FLOAT, GL_FALSE, 0, 0); 
    GetError(); 
    glBindBuffer(GL_ARRAY_BUFFER, uiVBO[1]); 
    glBufferData(GL_ARRAY_BUFFER, 9*sizeof(float), fTriangleColor, GL_STATIC_DRAW); 
    glEnableVertexAttribArray(m_colAttr); 
    GetError(); 
    glVertexAttribPointer(m_colAttr, 3, GL_FLOAT, GL_FALSE, 0, 0); 
    GetError(); 
    glDrawArrays(GL_TRIANGLES, 0, 3); 
    GetError(); 
    glDisableVertexAttribArray(m_posAttr); 
    glDisableVertexAttribArray(m_colAttr); 
    glFlush(); 
    GetError(); 
} 
- (void)dealloc { 
    glDeleteProgram(program); 
    glDeleteBuffers(2, uiVBO); 
    glDeleteVertexArrays(1, uiVAO); 
    GetError(); 
} 
@end

error.h：

//// Prints OpenGL errors 
#ifndef __ERROR_H__ 
#define __ERROR_H__ 
#include <stdlib.h> 
#include <assert.h> 
#ifdef DEBUG 
#define GetError()\ 
{\ 
for (GLenum Error = glGetError(); (GL_NO_ERROR != Error); Error = glGetError())\ 
{\ 
switch (Error)\ 
{\ 
case GL_INVALID_ENUM:  printf("\n%s\n\n", "GL_INVALID_ENUM"  ); assert(0); break;\ 
case GL_INVALID_VALUE:  printf("\n%s\n\n", "GL_INVALID_VALUE" ); assert(0); break;\ 
case GL_INVALID_OPERATION: printf("\n%s\n\n", "GL_INVALID_OPERATION"); assert(0); break;\ 
case GL_OUT_OF_MEMORY:  printf("\n%s\n\n", "GL_OUT_OF_MEMORY" ); assert(0); break;\ 
default:                    break;\ 
}\ 
}\ 
} 
#else 
#define GetError() 
#endif /* DEBUG  */ 
#endif /* __ERROR_H__ */