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Kaezin

I need help starting out...

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Is there anything wrong with this?
int DrawGLScene(GLvoid)									// Here''s Where We Do All The Drawing
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);	// Clear The Screen And The Depth Buffer
	glLoadIdentity();									// Reset The View
	glTranslatef(0.0f,0.0f,-5.0f);

	glColor3f(0.5f,0.5f,1.0f);				// Set The Color To Blue One Time Only
	glBegin(GL_QUADS);					// Start Drawing Quads
		glVertex3f(-1.0f, 1.0f, 0.0f);			// Left And Up 1 Unit (Top Left)
		glVertex3f( 1.0f, 1.0f, 0.0f);			// Right And Up 1 Unit (Top Right)
		glVertex3f( 1.0f,-1.0f, 0.0f);				// Right And Down One Unit (Bottom Right)
		glVertex3f(-1.0f,-1.0f, 0.0f);			// Left And Down One Unit (Bottom Left)
	glEnd();

	return TRUE;						
}

I can''t seem to get anything to show on the screen.  Can anyone help me please?    

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Hi, try putting this in the line before you return:
SwapBuffers(hDC);

Kenneth Wilhelmsen
http://www.fsentertainment.com
--------------------------
He who joyfully marches to music in rank and file has already earned my contempt. He has
been given a large brain by mistake, since for him the spinal cord would fully suffice. This
disgrace to civilization should be done away with at once. Heroism at command, senseless
brutality, deplorable love-of-country stance, how violently I hate all this, how despicable and ignoble war is; I would rather be torn to shreds than be a part of so base an action! It is my conviction that killing under the cloak of war is nothing but an act of murder

[edited by - kenwi on July 30, 2002 4:03:58 PM]

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I really should have given the whole file; I already have SwapBuffers(hDC) in the WinMain. Here's the whole file:

    
/*
* This Code Was Created By Jeff Molofee 2000
* A HUGE Thanks To Fredric Echols For Cleaning Up
* And Optimizing The Base Code, Making It More Flexible!
* If You've Found This Code Useful, Please Let Me Know.
* Visit My Site At nehe.gamedev.net
*/

#include <windows.h> // Header File For Windows
#include <stdio.h> // Header File For Standard Input/Output
#include <gl\gl.h> // Header File For The OpenGL32 Library
#include <gl\glu.h> // Header File For The GLu32 Library
#include <gl\glaux.h> // Header File For The Glaux Library

HDC hDC=NULL; // Private GDI Device Context
HGLRC hRC=NULL; // Permanent Rendering Context
HWND hWnd=NULL; // Holds Our Window Handle
HINSTANCE hInstance; // Holds The Instance Of The Application

bool keys[256]; // Array Used For The Keyboard Routine
bool active=TRUE; // Window Active Flag Set To TRUE By Default
bool fullscreen=TRUE; // Fullscreen Flag Set To Fullscreen Mode By Default

GLfloat xrot; // X Rotation ( NEW )
GLfloat yrot; // Y Rotation ( NEW )
GLfloat zrot; // Z Rotation ( NEW )

GLuint texture[2]; // Storage For One Texture ( NEW )

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration For WndProc

AUX_RGBImageRec *LoadBMP(char *Filename) // Loads A Bitmap Image
{
FILE *File=NULL; // File Handle

if (!Filename) // Make Sure A Filename Was Given
{
return NULL; // If Not Return NULL
}

File=fopen(Filename,"r"); // Check To See If The File Exists

if (File) // Does The File Exist?
{
fclose(File); // Close The Handle
return auxDIBImageLoad(Filename); // Load The Bitmap And Return A Pointer
}

return NULL; // If Load Failed Return NULL
}

int LoadGLTextures() // Load Bitmaps And Convert To Textures
{
int Status=FALSE; // Status Indicator

AUX_RGBImageRec *TextureImage[1]; // Create Storage Space For The Texture

memset(TextureImage,0,sizeof(void *)*1); // Set The Pointer To NULL

// Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit
if (TextureImage[0]=LoadBMP("data/brick.bmp"))
{
Status=TRUE; // Set The Status To TRUE

glGenTextures(1, &texture[0]); // Create The Texture

// Typical Texture Generation Using Data From The Bitmap
glBindTexture(GL_TEXTURE_2D, texture[0]);
glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
}

if (TextureImage[0]) // If Texture Exists
{
if (TextureImage[0]->data) // If Texture Image Exists
{
free(TextureImage[0]->data); // Free The Texture Image Memory
}

free(TextureImage[0]); // Free The Image Structure
}

return Status; // Return The Status
}

GLvoid ReSizeGLScene(GLsizei width, GLsizei height) // Resize And Initialize The GL Window
{
if (height==0) // Prevent A Divide By Zero By
{
height=1; // Making Height Equal One
}

glViewport(0,0,width,height); // Reset The Current Viewport

glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix

// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
}

int InitGL(GLvoid) // All Setup For OpenGL Goes Here
{
if (!LoadGLTextures()) // Jump To Texture Loading Routine ( NEW )
{
return FALSE; // If Texture Didn't Load Return FALSE
}

glEnable(GL_TEXTURE_2D); // Enable Texture Mapping ( NEW )
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
return TRUE; // Initialization Went OK
}

int DrawGLScene(GLvoid) // Here's Where We Do All The Drawing
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
glLoadIdentity(); // Reset The View
glTranslatef(0.0f,0.0f,-5.0f);

//glRotatef(xrot,1.0f,0.0f,0.0f);

//glBindTexture(GL_TEXTURE_2D, texture[0]);

glColor3f(0.5f,0.5f,1.0f); // Set The Color To Blue One Time Only
glBegin(GL_QUADS); // Start Drawing Quads
glVertex3f(-1.0f, 1.0f, 0.0f); // Left And Up 1 Unit (Top Left)
glVertex3f( 1.0f, 1.0f, 0.0f); // Right And Up 1 Unit (Top Right)
glVertex3f( 1.0f,-1.0f, 0.0f); // Right And Down One Unit (Bottom Right)
glVertex3f(-1.0f,-1.0f, 0.0f); // Left And Down One Unit (Bottom Left)
glEnd();

return TRUE; // Keep Going
}

GLvoid KillGLWindow(GLvoid) // Properly Kill The Window
{
if (fullscreen) // Are We In Fullscreen Mode?
{
ChangeDisplaySettings(NULL,0); // If So Switch Back To The Desktop
ShowCursor(TRUE); // Show Mouse Pointer
}

if (hRC) // Do We Have A Rendering Context?
{
if (!wglMakeCurrent(NULL,NULL)) // Are We Able To Release The DC And RC Contexts?
{
MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
}

if (!wglDeleteContext(hRC)) // Are We Able To Delete The RC?
{
MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
}
hRC=NULL; // Set RC To NULL
}

if (hDC && !ReleaseDC(hWnd,hDC)) // Are We Able To Release The DC
{
MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hDC=NULL; // Set DC To NULL
}

if (hWnd && !DestroyWindow(hWnd)) // Are We Able To Destroy The Window?
{
MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hWnd=NULL; // Set hWnd To NULL
}

if (!UnregisterClass("OpenGL",hInstance)) // Are We Able To Unregister Class
{
MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION);
hInstance=NULL; // Set hInstance To NULL
}
}

/* This Code Creates Our OpenGL Window. Parameters Are: *
* title - Title To Appear At The Top Of The Window *
* width - Width Of The GL Window Or Fullscreen Mode *
* height - Height Of The GL Window Or Fullscreen Mode *
* bits - Number Of Bits To Use For Color (8/16/24/32) *
* fullscreenflag - Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE) */


BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag)
{
GLuint PixelFormat; // Holds The Results After Searching For A Match

WNDCLASS wc; // Windows Class Structure

DWORD dwExStyle; // Window Extended Style

DWORD dwStyle; // Window Style

RECT WindowRect; // Grabs Rectangle Upper Left / Lower Right Values

WindowRect.left=(long)0; // Set Left Value To 0

WindowRect.right=(long)width; // Set Right Value To Requested Width

WindowRect.top=(long)0; // Set Top Value To 0

WindowRect.bottom=(long)height; // Set Bottom Value To Requested Height


fullscreen=fullscreenflag; // Set The Global Fullscreen Flag


hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window

wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window.

wc.lpfnWndProc = (WNDPROC) WndProc; // WndProc Handles Messages

wc.cbClsExtra = 0; // No Extra Window Data

wc.cbWndExtra = 0; // No Extra Window Data

wc.hInstance = hInstance; // Set The Instance

wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon

wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer

wc.hbrBackground = NULL; // No Background Required For GL

wc.lpszMenuName = NULL; // We Don't Want A Menu

wc.lpszClassName = "OpenGL"; // Set The Class Name


if (!RegisterClass(&wc)) // Attempt To Register The Window Class

{
MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

if (fullscreen) // Attempt Fullscreen Mode?

{
DEVMODE dmScreenSettings; // Device Mode

memset(&dmScreenSettings,0,sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared

dmScreenSettings.dmSize=sizeof(dmScreenSettings); // Size Of The Devmode Structure

dmScreenSettings.dmPelsWidth = width; // Selected Screen Width

dmScreenSettings.dmPelsHeight = height; // Selected Screen Height

dmScreenSettings.dmBitsPerPel = bits; // Selected Bits Per Pixel

dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

// Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar.

if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
{
// If The Mode Fails, Offer Two Options. Quit Or Use Windowed Mode.

if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
{
fullscreen=FALSE; // Windowed Mode Selected. Fullscreen = FALSE

}
else
{
// Pop Up A Message Box Letting User Know The Program Is Closing.

MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP);
return FALSE; // Return FALSE

}
}
}

if (fullscreen) // Are We Still In Fullscreen Mode?

{
dwExStyle=WS_EX_APPWINDOW; // Window Extended Style

dwStyle=WS_POPUP; // Windows Style

ShowCursor(FALSE); // Hide Mouse Pointer

}
else
{
dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window Extended Style

dwStyle=WS_OVERLAPPEDWINDOW; // Windows Style

}

AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust Window To True Requested Size


// Create The Window

if (!(hWnd=CreateWindowEx( dwExStyle, // Extended Style For The Window

"OpenGL", // Class Name

title, // Window Title

dwStyle | // Defined Window Style

WS_CLIPSIBLINGS | // Required Window Style

WS_CLIPCHILDREN, // Required Window Style

0, 0, // Window Position

WindowRect.right-WindowRect.left, // Calculate Window Width

WindowRect.bottom-WindowRect.top, // Calculate Window Height

NULL, // No Parent Window

NULL, // No Menu

hInstance, // Instance

NULL))) // Dont Pass Anything To WM_CREATE

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

static PIXELFORMATDESCRIPTOR pfd= // pfd Tells Windows How We Want Things To Be

{
sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor

1, // Version Number

PFD_DRAW_TO_WINDOW | // Format Must Support Window

PFD_SUPPORT_OPENGL | // Format Must Support OpenGL

PFD_DOUBLEBUFFER, // Must Support Double Buffering

PFD_TYPE_RGBA, // Request An RGBA Format

bits, // Select Our Color Depth

0, 0, 0, 0, 0, 0, // Color Bits Ignored

0, // No Alpha Buffer

0, // Shift Bit Ignored

0, // No Accumulation Buffer

0, 0, 0, 0, // Accumulation Bits Ignored

16, // 16Bit Z-Buffer (Depth Buffer)

0, // No Stencil Buffer

0, // No Auxiliary Buffer

PFD_MAIN_PLANE, // Main Drawing Layer

0, // Reserved

0, 0, 0 // Layer Masks Ignored

};

if (!(hDC=GetDC(hWnd))) // Did We Get A Device Context?

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) // Did Windows Find A Matching Pixel Format?

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

if(!SetPixelFormat(hDC,PixelFormat,&pfd)) // Are We Able To Set The Pixel Format?

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

if (!(hRC=wglCreateContext(hDC))) // Are We Able To Get A Rendering Context?

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

if(!wglMakeCurrent(hDC,hRC)) // Try To Activate The Rendering Context

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

ShowWindow(hWnd,SW_SHOW); // Show The Window

SetForegroundWindow(hWnd); // Slightly Higher Priority

SetFocus(hWnd); // Sets Keyboard Focus To The Window

ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen


if (!InitGL()) // Initialize Our Newly Created GL Window

{
KillGLWindow(); // Reset The Display

MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
return FALSE; // Return FALSE

}

return TRUE; // Success

}

LRESULT CALLBACK WndProc( HWND hWnd, // Handle For This Window

UINT uMsg, // Message For This Window

WPARAM wParam, // Additional Message Information

LPARAM lParam) // Additional Message Information

{
switch (uMsg) // Check For Windows Messages

{
case WM_ACTIVATE: // Watch For Window Activate Message

{
if (!HIWORD(wParam)) // Check Minimization State

{
active=TRUE; // Program Is Active

}
else
{
active=FALSE; // Program Is No Longer Active

}

return 0; // Return To The Message Loop

}

case WM_SYSCOMMAND: // Intercept System Commands

{
switch (wParam) // Check System Calls

{
case SC_SCREENSAVE: // Screensaver Trying To Start?

case SC_MONITORPOWER: // Monitor Trying To Enter Powersave?

return 0; // Prevent From Happening

}
break; // Exit

}

case WM_CLOSE: // Did We Receive A Close Message?

{
PostQuitMessage(0); // Send A Quit Message

return 0; // Jump Back

}

case WM_KEYDOWN: // Is A Key Being Held Down?

{
keys[wParam] = TRUE; // If So, Mark It As TRUE

return 0; // Jump Back

}

case WM_KEYUP: // Has A Key Been Released?

{
keys[wParam] = FALSE; // If So, Mark It As FALSE

return 0; // Jump Back

}

case WM_SIZE: // Resize The OpenGL Window

{
ReSizeGLScene(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height

return 0; // Jump Back

}
}

// Pass All Unhandled Messages To DefWindowProc

return DefWindowProc(hWnd,uMsg,wParam,lParam);
}

int WINAPI WinMain( HINSTANCE hInstance, // Instance

HINSTANCE hPrevInstance, // Previous Instance

LPSTR lpCmdLine, // Command Line Parameters

int nCmdShow) // Window Show State

{
MSG msg; // Windows Message Structure

BOOL done=FALSE; // Bool Variable To Exit Loop


// Ask The User Which Screen Mode They Prefer

if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
{
fullscreen=FALSE; // Windowed Mode

}

// Create Our OpenGL Window

if (!CreateGLWindow("NeHe's Texture Mapping Tutorial",640,480,16,fullscreen))
{
return 0; // Quit If Window Was Not Created

}

while(!done) // Loop That Runs While done=FALSE

{
if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting?

{
if (msg.message==WM_QUIT) // Have We Received A Quit Message?

{
done=TRUE; // If So done=TRUE

}
else // If Not, Deal With Window Messages

{
TranslateMessage(&msg); // Translate The Message

DispatchMessage(&msg); // Dispatch The Message

}
}
else // If There Are No Messages

{
// Draw The Scene. Watch For ESC Key And Quit Messages From DrawGLScene()

if ((active && !DrawGLScene()) || keys[VK_ESCAPE]) // Active? Was There A Quit Received?

{
done=TRUE; // ESC or DrawGLScene Signalled A Quit

}
else // Not Time To Quit, Update Screen

{
SwapBuffers(hDC); // Swap Buffers (Double Buffering)

}

if (keys[VK_F1]) // Is F1 Being Pressed?

{
keys[VK_F1]=FALSE; // If So Make Key FALSE

KillGLWindow(); // Kill Our Current Window

fullscreen=!fullscreen; // Toggle Fullscreen / Windowed Mode

// Recreate Our OpenGL Window

if (!CreateGLWindow("NeHe's Texture Mapping Tutorial",640,480,16,fullscreen))
{
return 0; // Quit If Window Was Not Created

}
}
}
}

// Shutdown

KillGLWindow(); // Kill The Window

return (msg.wParam); // Exit The Program

}

I'm using NeHe's modified tutorial number 6.

[edited by - Kaezin on July 30, 2002 4:31:20 PM]

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***This isn''t going to fix your problem, but it is a usual ''gotcha'' for beginners***
Double check your polygon winding order when you are trying to figure out why polygons arn''t appearing. The default is COUNTER clockwise. But you can change that with a simple OpenGL call. I noticed that your Quad was going Clockwise, so I bring it up...

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I thought you could go clockwise or counterclockwise, just as long as you don't jump around randomly? Thanks, though, I'll try everyone's suggestions =Þ

*EDIT*
The NULL thing worked, thanks!

[edited by - Kaezin on July 30, 2002 12:44:52 AM]

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Guest Anonymous Poster
If you draw it clockwise the back of the polygon is facing you and it will not be rendered if a texture is added to it

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So textures are done clockwise and quad points counter clockwise. Hmmmm - that makes sense

Anyway, up to now I would always just do clockwise for both and it would draw the textures fine. I also draw both front and back faces though.


Luigi Pino
www.lp23.com

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Forget what I said - that''s just the way I did it. Anyway, as an aside you can change the orientation with glFrontFace() with the parameter GL_CW or GL_CCW.


Luigi Pino
www.lp23.com

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The problem is that you had textures enabled. Since there was a bound texture, and you did not specify texture coordinates, nothing showed up. You can use PmanC''s suggestion, but I prefer to actually disable texturing instead of binding a non-existent texture.

glDisable(GL_TEXTURE_2D);
but make sure you re-enable it after you draw the any non-textured stuff:
glEnable(GL_TEXTURE_2D);

***500 error***

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