I’m trying to make my first polygon.
Because I wrote a code, complied it and voila … the triangle is not displayed 🙁
What is wrong with this code?
#pragma once
#include <Windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <gl\GL.h>
#include <gl\glu.h>
#include <gl\glut.h>
HDC hDC=NULL;
HGLRC hRC=NULL;
GLvoid GL_ReSizeGLScene(GLsizei width, GLsizei height);
int GL_init( GLvoid );
int GL_drawit( GLvoid );
typedef struct {
HWND hWnd;
} Glab_t;
static Glab_t glab;
char szClassName[ ] = "GLab";
static LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
switch (message) {
case WM_DESTROY:
PostQuitMessage (0);
break;
case WM_SIZE:
GL_ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));
break;
default:
return DefWindowProc (hwnd, message, wParam, lParam);
}
return 0;
}
int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) {
MSG messages;
RECT rect;
WNDCLASSEX wndClass;
int screenWidth, screenHeight;
int x, y, w, h;
GLuint PixelFormat;
screenWidth = GetSystemMetrics(SM_CXSCREEN);
screenHeight = GetSystemMetrics(SM_CYSCREEN);
rect.left = (screenWidth - 582) / 2;
rect.top = (screenHeight - 358) / 2;
rect.right = rect.left + 582;
rect.bottom = rect.top + 358;
x = rect.left;
y = rect.top;
w = 640;
h = 480;
wndClass.hInstance = hInstance;
wndClass.lpszClassName = szClassName;
wndClass.lpfnWndProc = WindowProcedure;
wndClass.style = CS_DBLCLKS;
wndClass.cbSize = sizeof (WNDCLASSEX);
wndClass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wndClass.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wndClass.hCursor = LoadCursor (NULL, IDC_ARROW);
wndClass.lpszMenuName = NULL;
wndClass.cbClsExtra = 0;
wndClass.cbWndExtra = 0;
wndClass.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
if (!RegisterClassEx (&wndClass)) {
return 0;
}
glab.hWnd = CreateWindowEx (
0,
szClassName,
"GLab - OpenGL",
WS_OVERLAPPEDWINDOW,
x,
y,
w,
h,
HWND_DESKTOP,
NULL,
hInstance,
NULL
);
static PIXELFORMATDESCRIPTOR pfd= {
sizeof(PIXELFORMATDESCRIPTOR),
1,
PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA,
16, // Can be 32 tough :)
0, 0, 0, 0, 0, 0,
0,
0,
0,
0, 0, 0, 0,
16,
0,
0,
PFD_MAIN_PLANE,
0,
0, 0, 0
};
if (!(hDC=GetDC(glab.hWnd))) {
MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE;
}
if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) {
MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE;
}
if(!SetPixelFormat(hDC,PixelFormat,&pfd)) {
MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE;
}
if (!(hRC=wglCreateContext(hDC))) {
MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE;
}
if(!wglMakeCurrent(hDC,hRC)) {
MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE;
}
ShowWindow (glab.hWnd, nCmdShow);
SetForegroundWindow(glab.hWnd);
SetFocus(glab.hWnd);
GL_ReSizeGLScene( w, h );
if (!GL_init() ) {
MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return false;
}
if( !GL_drawit() ) {
MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return false;
}
while (GetMessage (&messages, NULL, 0, 0)) {
TranslateMessage(&messages);
DispatchMessage(&messages);
}
return messages.wParam;
}
GLvoid GL_ReSizeGLScene(GLsizei width, GLsizei height) {
if (height==0) {
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();
}
int GL_init( GLvoid ) {
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
glClearDepth(1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
return true;
}
int GL_drawit( GLvoid ) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
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();
return true;
}
Using MC Visual C++ 2010 Express and OpenGL 1.4.
You need a
SwapBuffers()call in there after you render your scene:EDIT: I also moved your
GL_drawit()call to the event loop so it redraws in response to resize events. Well, any event at all really.