我目前正在学习OpenGL,并且一直在使用SDL2,当我尝试运行一个简单的程序时,我得到一个黑屏。任何帮助,将不胜感激。我正在使用OpenGL 2.1和vc编译器。
这是我的代码
#include <iostream>
#include <SDL.h>
#include <Windows.h>
#include <gl/GL.h>
#include <gl/GLU.h>
using namespace std;
int main(int argc, char* argv[]) {
int width, height;
width = 640;
height = 480;
SDL_Init(SDL_INIT_EVERYTHING);
SDL_Window* win;
win = SDL_CreateWindow("SDL Application", 100, 100, width, height, SDL_WINDOW_SHOWN | SDL_WINDOW_OPENGL);
SDL_GLContext context;
context = SDL_GL_CreateContext(win);
SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
height = (height <= 0) ? height = height : height = 1;
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, (GLfloat) width / (GLfloat) height, 0.1f, 100.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
SDL_GL_SwapWindow(win);
glColor3f(1.0f, 1.0f, 1.0f);
glTranslatef(-1.5f, 0.0f, -6.0f);
glBegin(GL_TRIANGLES);
glVertex3f(0.0f, 1.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f);
glEnd();
glTranslatef(3.0f, 0.0f, 0.0f);
glBegin(GL_QUADS);
glVertex3f(-1.0f, 1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glEnd();
SDL_Delay(5000);
SDL_GL_DeleteContext(context);
SDL_DestroyWindow(win);
SDL_Quit();
return 0;
}
答案 0 :(得分:1)
这些顺序是错误的:
SDL_GLContext context; context = SDL_GL_CreateContext(win); SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1); SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
必须在创建上下文之前设置OpenGL上下文属性(它们是控制上下文创建过程的状态变量)。
这没有任何意义:首先你清除,然后交换,然后你绘制(进入一个未定义的后缓冲区,因为后交换缓冲区的内容在交换后未定义)然后你不< / em>交换。
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); SDL_GL_SwapWindow(win); glColor3f(1.0f, 1.0f, 1.0f); /* this translate will move the triangle out * of the NDC space i.e. it gets clipped or * won't be visible at all. */ glTranslatef(-1.5f, 0.0f, -6.0f); glBegin(GL_TRIANGLES); glVertex3f(0.0f, 1.0f, 0.0f);
这应该是
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(1.0f, 1.0f, 1.0f);
glBegin(GL_TRIANGLES);
glVertex3f(0.0f, 1.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f);
glEnd();
glTranslatef(3.0f, 0.0f, 0.0f);
glBegin(GL_QUADS);
glVertex3f(-1.0f, 1.0f, 0.0f);
glVertex3f(1.0f, 1.0f, 0.0f);
glVertex3f(1.0f, -1.0f, 0.0f);
glVertex3f(-1.0f, -1.0f, 0.0f);
glEnd();
SDL_GL_SwapWindow(win);
SDL_Delay(5000);
完全没有任何意义。其余的代码仍然存在很多问题,但如果你改变它,你至少应该在黑色地面上看到一些白色三角形。