OpenGL无法与VBO绘制三角形
我最近开始使用OpenGL编程，发现这个教程网站名为“open.gl”。 第二篇教程解释了使用“现代”OpenGL绘制多边形的过程，但在紧跟教程之后，我无法在屏幕上看到我的三角形。 我一直在四处搜寻，想知道我错过了什么，但到目前为止，我不知道为什么我的三角形不能在屏幕上绘制。 我错过了一些非常简单的东西吗？
我使用SDL创建窗口和GLEW来检查硬件上的OpenGL函数，就像在教程中一样。 我也做了检查，看看OpenGL上下文版本是“3.2”。
#include <stdio.h>
#include "glew.h"
#include <SDL.h>
#include <SDL_opengl.h>
const int SCREEN_WIDTH = 800;
const int SCREEN_HEIGHT = 600;
const GLchar* vertexSource =
"#version 150 coren"
"in vec2 position;"
"void main() {"
" gl_Position = vec4(position, 0.0, 1.0);"
"}";
const GLchar* fragmentSource =
"#version 150 coren"
"out vec4 outColor;"
"void main() {"
" outColor = vec4(1.0, 1.0, 1.0, 1.0,);"
"}";
GLfloat vertices[] =
{
0.0f, 0.5f,
0.5f, -0.5f,
-0.5f, -0.5f
};
int main( int argc, char* argv[] )
{
SDL_Init( SDL_INIT_VIDEO );
// OpenGL core profile - deprecated functions are disabled
SDL_GL_SetAttribute( SDL_GL_CONTEXT_PROFILE_MASK,
SDL_GL_CONTEXT_PROFILE_CORE );
// OpenGL version 3.2
SDL_GL_SetAttribute( SDL_GL_CONTEXT_MAJOR_VERSION, 3 );
SDL_GL_SetAttribute( SDL_GL_CONTEXT_MINOR_VERSION, 2 );
SDL_Window* window = SDL_CreateWindow( "SDL OpenGL",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
SCREEN_WIDTH,
SCREEN_HEIGHT,
SDL_WINDOW_OPENGL );
SDL_GLContext context = SDL_GL_CreateContext( window );
glewExperimental = GL_TRUE;
if( glewInit() != GLEW_OK )
{
printf( "Failed to init glew!n" );
return -1;
}
glClearColor( 0.0f, 0.0f, 0.3f, 1.0f );
GLuint vao;
glGenVertexArrays( 1, &vao );
glBindVertexArray(vao);
GLuint vbo;
glGenBuffers( 1, &vbo );
glBindBuffer( GL_ARRAY_BUFFER, vbo );
glBufferData( GL_ARRAY_BUFFER,
sizeof(vertices),
vertices,
GL_STATIC_DRAW );
GLuint vertexShader = glCreateShader( GL_VERTEX_SHADER );
glShaderSource( vertexShader, 1, &vertexSource, NULL );
glCompileShader( vertexShader );
GLuint fragmentShader = glCreateShader( GL_FRAGMENT_SHADER );
glShaderSource( fragmentShader, 1, &fragmentSource, NULL );
glCompileShader( fragmentShader );
GLuint shaderProgram = glCreateProgram();
glAttachShader( shaderProgram, vertexShader );
glAttachShader( shaderProgram, fragmentShader );
glBindFragDataLocation( shaderProgram, 0, "outColor" );
glLinkProgram( shaderProgram );
glUseProgram( shaderProgram );
GLuint posAttrib = glGetAttribLocation( shaderProgram, "position" );
glEnableVertexAttribArray( posAttrib );
glVertexAttribPointer( posAttrib, 2, GL_FLOAT, GL_FALSE, 0, 0 );
SDL_Event windowEvent;
while( true )
{
if( SDL_PollEvent( &windowEvent ) )
{
if( windowEvent.type == SDL_QUIT )
break;
if( windowEvent.type == SDL_KEYUP &&
windowEvent.key.keysym.sym == SDLK_ESCAPE )
break;
}
glClear( GL_COLOR_BUFFER_BIT );
glDrawArrays( GL_TRIANGLES, 0, 3 );
SDL_GL_SwapWindow( window );
}
glDeleteProgram( shaderProgram );
glDeleteShader( fragmentShader );
glDeleteShader( vertexShader );
glDeleteBuffers( 1, &vbo );
glDeleteVertexArrays( 1, &vao );
SDL_GL_DeleteContext( context );
SDL_Quit();
return 0;
}