当我尝试使用OpenGL渲染三角形时，出现空白屏幕。
我正在关注a tutorial，除了核心配置文件代码块外，我的代码与本教程的代码相同。
我正在Mac上运行
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
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") << " shader" << std::endl;
std::cout << message << std::endl;
}
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(void)
{
GLFWwindow* window;
/* Initialize the library */
if (!glfwInit())
return -1;
/* Core profile */
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
/* Create a windowed mode window and its OpenGL context */
window = glfwCreateWindow(640, 480, "Hello World", NULL, NULL);
if (!window)
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent(window);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
if(glewInit() != GLEW_OK)
std::cout <<"error!";
std::cout << "Version: " << glGetString(GL_VERSION) << " :Version " << std::endl;
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 410 core\n"
"\n"
"layout(location = 0) in vec4 position;"
"\n"
"void main(){\n"
" gl_Position = position;\n"
"}\n";
std::string fragmentShader =
"#version 410 core\n"
"\n"
"layout(location = 0) out vec4 color;"
"\n"
"void main(){\n"
" color = vec4(1.0, 0.0, 0.0, 1.0);\n"
"}\n";
unsigned int shader = CreateShader(vertexShader, fragmentShader);
glUseProgram(shader);
/* Loop until the user closes the window */
while (!glfwWindowShouldClose(window))
{
/* Render here */
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 3);
/* glBegin(GL_TRIANGLES);
glVertex2f(-0.5, -0.5);
glVertex2f(0, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
*/
/* Swap front and back buffers */
glfwSwapBuffers(window);
/* Poll for and process events */
glfwPollEvents();
}
glfwTerminate();
return 0;
}
答案 0 :(得分：2)
一些问题：
#version 410着色器；您请求的GL上下文版本应达到或超过您要定位的着色器版本。将您请求的GL版本提高到4.1，或者将GLSL #version放回150。glfwWindowHint()呼叫glfwCreateWindow() 不会做任何有用的事情；它只会影响 next glfwCreateWindow()调用。glValidateProgram()本身并不像听起来那样有用（如果您不实际检查GL_VALIDATE_STATUS，这无疑会有用）；如果要验证程序链接成功，则查询GL_LINK_STATUS。一起：
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <cstdarg>
struct Program
{
static GLuint Load( const char* shader, ... )
{
GLuint prog = glCreateProgram();
va_list args;
va_start( args, shader );
while( shader )
{
const GLenum type = va_arg( args, GLenum );
AttachShader( prog, type, shader );
shader = va_arg( args, const char* );
}
va_end( args );
glLinkProgram( prog );
CheckStatus( prog );
return prog;
}
private:
static void CheckStatus( GLuint obj )
{
GLint status = GL_FALSE;
if( glIsShader(obj) ) glGetShaderiv( obj, GL_COMPILE_STATUS, &status );
if( glIsProgram(obj) ) glGetProgramiv( obj, GL_LINK_STATUS, &status );
if( status == GL_TRUE ) return;
GLchar log[ 1 << 15 ] = { 0 };
if( glIsShader(obj) ) glGetShaderInfoLog( obj, sizeof(log), NULL, log );
if( glIsProgram(obj) ) glGetProgramInfoLog( obj, sizeof(log), NULL, log );
std::cerr << log << std::endl;
std::exit( EXIT_FAILURE );
}
static void AttachShader( GLuint program, GLenum type, const char* src )
{
GLuint shader = glCreateShader( type );
glShaderSource( shader, 1, &src, NULL );
glCompileShader( shader );
CheckStatus( shader );
glAttachShader( program, shader );
glDeleteShader( shader );
}
};
int main()
{
if( !glfwInit() )
return -1;
/* Core profile */
glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE );
glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 4 );
glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 1 );
/* Create a windowed mode window and its OpenGL context */
GLFWwindow* window = glfwCreateWindow( 640, 480, "Hello World", NULL, NULL );
if( !window )
{
glfwTerminate();
return -1;
}
/* Make the window's context current */
glfwMakeContextCurrent( window );
if( glewInit() != GLEW_OK )
std::cout << "error!";
std::cout << "Version: " << glGetString( GL_VERSION ) << " :Version " << std::endl;
GLuint vao = 0;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
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 410 core\n"
"layout(location = 0) in vec4 position;\n"
"void main(){\n"
" gl_Position = position;\n"
"}\n";
std::string fragmentShader =
"#version 410 core\n"
"layout(location = 0) out vec4 color;\n"
"void main(){\n"
" color = vec4(1.0, 0.0, 0.0, 1.0);\n"
"}\n";
unsigned int shader = Program::Load( vertexShader.c_str(), GL_VERTEX_SHADER, fragmentShader.c_str(), GL_FRAGMENT_SHADER, NULL );
glUseProgram( shader );
while( !glfwWindowShouldClose( window ) )
{
glClear( GL_COLOR_BUFFER_BIT );
glDrawArrays( GL_TRIANGLES, 0, 3 );
glfwSwapBuffers( window );
glfwPollEvents();
}
glfwTerminate();
return 0;
}