我正在学习C ++中的OpenGL教程(Youtube上的Cherno)。我有以下代码,但无论我尝试什么,我都无法得到一个三角形。创建一个窗口,我没有错误等,我甚至可以用glClearColor改变背面颜色。但没有三角形!
有关信息,我通过Homebrew安装了GLFW / GLEW,我正在使用CLion。
CMakeList.txt
cmake_minimum_required(VERSION 3.3)
project(Lib_Test)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -framework Cocoa -framework OpenGL -framework IOKit")
set(SOURCE_FILES src/main.cpp CMakeLists.txt)
# add extra include directories
include_directories(/usr/local/include)
# add extra lib directories
link_directories(/usr/local/lib)
add_executable(Lib_Test main.cpp)
target_link_libraries(Lib_Test glfw)
target_link_libraries(Lib_Test glew)
find_package (GLM REQUIRED)
include_directories(include)
的main.cpp
#include <stdio.h>
#include <iostream>
#include <GL/glew.h>
#include <GLFW/glfw3.h>
static unsigned int CompileShader(unsigned int type, const std::string& source)
{
unsigned int id = glCreateShader(type);
const char* src = source.c_str();
glShaderSource(id, 1, &src, nullptr);
glCompileShader(id);
int result;
glGetShaderiv(id, GL_COMPILE_STATUS, &result);
if (result == GL_FALSE)
{
int length;
glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
char* message = (char*)alloca(length * sizeof(char));
glGetShaderInfoLog(id, length, &length, message);
std::cout << "Failed to compile " <<
(type == GL_VERTEX_SHADER ? "vertex" : "fragment") << std::endl;
std::cout << message << std::endl;
glDeleteShader(id);
return 0;
}
return id;
}
static unsigned int CreateShader(const std::string& vertexShader, const std::string& fragmentShader)
{
unsigned int program = glCreateProgram();
unsigned int vs = CompileShader(GL_VERTEX_SHADER, vertexShader);
unsigned int fs = CompileShader(GL_FRAGMENT_SHADER, fragmentShader);
glAttachShader(program, vs);
glAttachShader(program, fs);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(vs);
glDeleteShader(fs);
return program;
}
int main(){
// Initialise GLFW
if( !glfwInit() )
{
fprintf( stderr, "Failed to initialize GLFW\n" );
return -1;
}
glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4); // We want OpenGL 3.3
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window; // (In the accompanying source code, this variable is global for simplicity)
window = glfwCreateWindow( 640, 480, "My App", NULL, NULL);
if( window == NULL ){
fprintf( stderr, "Failed to open GLFW window.\n" );
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glewExperimental=true; // Needed in core profile
if (glewInit() != GLEW_OK) {
fprintf(stderr, "Failed to initialize GLEW\n");
return -1;
}
float positions[6] = {
-0.5f, -0.5f,
0.0f, 0.5f,
0.5f, -0.5f
};
unsigned int buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), positions, GL_STATIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float)*2, 0);
std::string vertexShader =
"#version 330 core\n";
"\n";
"layout(location = 0) in vec4 position;\n";
"\n";
"void main()\n";
"{\n";
" gl_Position = position\n";
"}\n";
std::string fragmentShader =
"#version 330 core\n";
"\n";
"layout(location = 0) out vec4 color;\n";
"\n";
"void main()\n";
"{\n";
" color = vec4(1.0, 0.0, 0.0, 1.0)\n";
"}\n";
unsigned int shader = CreateShader(vertexShader, fragmentShader);
glUseProgram(shader);
while( !glfwWindowShouldClose(window) )
{
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0 ,3);
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwTerminate();
return 0;
}
答案 0 :(得分:2)
你必须创建&amp;在Core上下文中绑定VAO,它不像在兼容性上下文中那样是可选的。
答案 1 :(得分:1)
除了genpflaut的回答,我还提到你的着色器代码根本不会编译。
您必须删除字符串文字之间的分号,并在color = vec4(1.0, 0.0, 0.0, 1.0)
之后删除分号。
你的代码看起来应该是这样的:
std::string vertexShader =
"#version 330 core\n"
"\n"
"layout(location = 0) in vec4 position;\n"
"\n"
"void main()\n"
"{\n"
" gl_Position = position;\n"
"}\n";
std::string fragmentShader =
"#version 330 core\n"
"\n"
"layout(location = 0) out vec4 color;\n"
"\n"
"void main()\n"
"{\n"
" color = vec4(1.0, 0.0, 0.0, 1.0);\n"
"}\n";
如果生成并绑定顶点数组对象,则在生成缓冲区对象之前,代码将正常运行。
在glBindBuffer(GL_ARRAY_BUFFER, buffer)
之前添加以下行:
unsigned int vao;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
请参阅OpenGL 3.3 core profile specification, E.2.2 Removed Features, page 344
也不推荐使用默认的顶点数组对象(名称为零)。当没有绑定缓冲区对象或没有绑定顶点数组对象时调用
VertexAttribPointer
将生成INVALID_OPERATION错误,因为在没有绑定顶点数组对象时将调用任何数组绘制命令。