drawing cylinders from scratch

[fallout]

Hi,

I'm trying to draw a cylinder from scratch. I can't seem to find anywhere on the net that will tell me howto do this. Can anybody point me to a good tutorial on howto build cylinders and other round objects from scratch??

Thanks!

[endash]

Use a triangle strip and assign vertices based on r*sin(theta), r*cos(theta), +/- (height/2).

/*
*A P P L I C A T I O N I D E N T I F I C A T I O N
*
* OPEN GL
* CYLINDER VER 0.00001
*
*/

/*I N C L U D E S*/
#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>

/* W I N D O W S G L O B A L S, D E F I N E S A N D P R O T O T Y P E S */
/*Windows Globals*/
/*Make the class name into a global variable*/
CHAR szAppName[]="Win OpenGL";

HWND ghWnd; /* handle for our window */
HDC ghDC; /* handle for device context */
HGLRC ghRC; /* handle for render context */

/*Defines*/
#define SWAPBUFFERS SwapBuffers(ghDC) /*makes scene visible under current device context*/
#define BLACK_INDEX 0 /*black for background*/
#define RED_INDEX 13 /*green for wireframe globe object*/
#define WIDTH 640 /*starting window pixel width*/
#define HEIGHT 480 /*starting window pixel height*/

/*Prototypes or procedures for window and pixel format*/
LONG WINAPI MainWndProc (HWND, UINT, WPARAM, LPARAM);
BOOL bSetupPixelFormat(HDC);

/* O P E N GL G L O B A L S, D E F I N E S A N D P R O T O T Y P E S */
/*OpenGL globals*/
GLfloat cylinderDiam, cylinderHeight, diaminc, heightinc;
GLdouble radius;

/*OpenGL defines*/
#define CYLINDER 1 /*The object to be rendered*/

/*OpenGL prototypes or functions*/
GLvoid resize(GLsizei, GLsizei);
GLvoid initializeGL(GLsizei, GLsizei);
GLvoid drawScene(GLvoid);
void endCylinderView( GLdouble, GLdouble, GLdouble, GLdouble);



/* R E G I S T E R F R A M E C L A S S A N D C R E A T E A S W I N D O W */

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
MSG msg;
WNDCLASS wndclass;

/* Register the frame class */
wndclass.style = 0;
wndclass.lpfnWndProc = (WNDPROC)MainWndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (hInstance, szAppName);
wndclass.hCursor = LoadCursor (NULL,IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wndclass.lpszMenuName = szAppName;
wndclass.lpszClassName = szAppName;

if (!RegisterClass (&wndclass) )
return FALSE;

/* Create the frame */
ghWnd = CreateWindow (szAppName,
"CYLINDER VER 0.0001",
WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
CW_USEDEFAULT,
CW_USEDEFAULT,
WIDTH,
HEIGHT,
NULL,
NULL,
hInstance,
NULL);

/* make sure window was created */
if (!ghWnd)
return FALSE;

/* show and update main window */
ShowWindow (ghWnd, nCmdShow);

UpdateWindow (ghWnd);

/* animation loop */
while (1) {
/*
* Process all pending messages
*/

while (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE) == TRUE)
{
if (GetMessage(&msg, NULL, 0, 0) )
{
TranslateMessage(&msg);
DispatchMessage(&msg);
} else {
return TRUE;
}
}
drawScene();
}
}


/* W I N 32 A P I W I N D O W´ s G E T D E V I C E C O N T E X T */
/* I T´ S R E N D E R I N G C O N T E X T */
/* A N D U S E R K E Y B O A R D R O U T I N E S */
/* main window procedure */
LONG WINAPI MainWndProc (
HWND hWnd, /*handle for our window */
UINT uMsg, /*messages*/
WPARAM wParam,
LPARAM lParam)
{
LONG lRet = 1;
PAINTSTRUCT ps;
RECT rect;

switch (uMsg) {

/*Win procedural call to get device context with window´s handle*/
/*Win procedural call to get render context concurrent with device context*/
case WM_CREATE:
ghDC = GetDC(hWnd);
if (!bSetupPixelFormat(ghDC))
PostQuitMessage (0);

ghRC = wglCreateContext(ghDC);
wglMakeCurrent(ghDC, ghRC);
GetClientRect(hWnd, &rect);
initializeGL(rect.right, rect.bottom);
break;

/*Win32 Api Paint*/
case WM_PAINT:
BeginPaint(hWnd, &ps);
EndPaint(hWnd, &ps);
break;
/*Win32 Api window´s size*/
case WM_SIZE:
GetClientRect(hWnd, &rect);
resize(rect.right, rect.bottom);
break;

/*Win32 Api to close window and reset render and device context to zero*/
case WM_CLOSE:
if (ghRC)
wglDeleteContext(ghRC);
if (ghDC)
ReleaseDC(hWnd, ghDC);
ghRC = 0;
ghDC = 0;

DestroyWindow (hWnd);
break;

/*Win32 Api to destroy window and delete render and device context*/
case WM_DESTROY:
if (ghRC)
wglDeleteContext(ghRC);
if (ghDC)
ReleaseDC(hWnd, ghDC);
PostQuitMessage (0);
break;

/*User controlled Kyboard routines*/
case WM_KEYDOWN:
switch (wParam) {
case VK_LEFT:
diaminc += 0.2F;
break;
case VK_RIGHT:
diaminc -= 0.2F;
break;
case VK_UP:
heightinc += 0.2F;
break;
case VK_DOWN:
heightinc -= 0.2F;
break;
}
/* Windows procedure for messages*/
default:
lRet = DefWindowProc (hWnd, uMsg, wParam, lParam);
break;
}

return lRet;
}

/* D E T E R M I N A T I O N O F D E P T H A N D P I X E L F O R M A T*/

BOOL bSetupPixelFormat(HDC hdc)
{
PIXELFORMATDESCRIPTOR pfd, *ppfd;
int pixelformat;

ppfd = &pfd;

ppfd->nSize = sizeof(PIXELFORMATDESCRIPTOR);
ppfd->nVersion = 1;
ppfd->dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER;
ppfd->dwLayerMask = PFD_MAIN_PLANE;
ppfd->iPixelType = PFD_TYPE_COLORINDEX;
ppfd->cColorBits = 8;
ppfd->cDepthBits = 16;
ppfd->cAccumBits = 0;
ppfd->cStencilBits = 0;

pixelformat = ChoosePixelFormat(hdc, ppfd);

if ( (pixelformat = ChoosePixelFormat(hdc, ppfd)) == 0 )
{
MessageBox(NULL, "ChoosePixelFormat failed", "Error", MB_OK);
return FALSE;
}

if (SetPixelFormat(hdc, pixelformat, ppfd) == FALSE)
{
MessageBox(NULL, "SetPixelFormat failed", "Error", MB_OK);
return FALSE;
}

return TRUE;
}


/* O P E N GL R E S I Z E A N D P R O J E C T I O N T R A N S F O R M S*/
GLvoid resize( GLsizei width, GLsizei height )
{
GLfloat aspect;

glViewport( 0, 0, width, height );

aspect = (GLfloat) width / height;

glMatrixMode( GL_PROJECTION );
glLoadIdentity();
gluPerspective( 45.0, aspect, 3.0, 7.0 );
glMatrixMode( GL_MODELVIEW );
}

/*SCENE SETUP*/

/* Object creation */
GLvoid createObjects()
{
GLUquadricObj *quadObj;

glNewList(CYLINDER, GL_COMPILE);
quadObj = gluNewQuadric ();
gluQuadricDrawStyle (quadObj, GLU_FILL);
gluQuadricNormals (quadObj, GLU_SMOOTH);
gluCylinder (quadObj, 0.3, 0.3, 0.6, 12, 2);
glEndList();

}

/* Function Initialize Scene objects */
GLvoid initializeGL(GLsizei width, GLsizei height)
{
GLfloat maxObjectSize, aspect;
GLdouble near_plane, far_plane;

/* Initial depth and background */
glClearIndex( (GLfloat)BLACK_INDEX);
glClearDepth( 1.0 );

/* Initial depth test */
glEnable(GL_DEPTH_TEST);

glMatrixMode( GL_PROJECTION );
aspect = (GLfloat) width / height;
gluPerspective( 45.0, aspect, 3.0, 7.0 );
glMatrixMode( GL_MODELVIEW );

near_plane = 3.0;
far_plane = 12.0;
maxObjectSize = 3.0F;
radius = near_plane + maxObjectSize/2.0;

cylinderDiam = 0.0F;
cylinderHeight = 0.0F;
diaminc = 3.0F;
heightinc = 0.0F;

createObjects();
}


/*Set model transform for object (i) using glTranslatef, glScalef, glRotatef, and/or equivalent.*/
void endCylinderView(GLdouble radius, GLdouble twist, GLdouble cylinderDiam,
GLdouble cylinderHeight)
{
glTranslated(0.0, 0.0, -radius);
glRotated(-twist, 0.0, 0.0, 1.0);
glRotated(-cylinderDiam, 1.0, 0.0, 0.0);
glRotated(cylinderHeight, 0.0, 0.0, 1.0);

}

/* O P E N GL R E F R E S H */

/* Final Function to Draw current scene objects, ect */

GLvoid drawScene(GLvoid)
{
/*Clear previous frame depth and color buffer enabling next frame*/
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

/*access OpenGl´s matrix stack to save transformations*/
glPushMatrix();

/*User´s Kayboard values*/
cylinderDiam += diaminc*.5;
cylinderHeight += heightinc*.5;

/*Call to object´s function with current values*/
endCylinderView(radius, 0, cylinderDiam, cylinderHeight);

/* Final Call for Objects to be rendered*/
glIndexi(RED_INDEX);
glCallList(CYLINDER);

/*restore OpenGl´s matrix stack transformations to continue to translatef*/
glPopMatrix();

/* Make scene visible */
SWAPBUFFERS;
}

/*
*
*
* OPEN GL
* CYLINDER
*
*/

/*I N C L U D E S*/
#include <windows.h>
#include <GL/gl.h>
#include <GL/glu.h>

/* W I N D O W S G L O B A L S, D E F I N E S A N D P R O T O T Y P E S */
/*Windows Globals*/
/*Make the class name into a global variable*/
CHAR szAppName[]="Win OpenGL";

HWND ghWnd; /* handle for our window */
HDC ghDC; /* handle for device context */
HGLRC ghRC; /* handle for render context */

/*Defines*/
#define SWAPBUFFERS SwapBuffers(ghDC) /*makes scene visible under current device context*/
#define BLACK_INDEX 0 /*black for background*/
#define RED_INDEX 13 /*green for wireframe globe object*/
#define WIDTH 640 /*starting window pixel width*/
#define HEIGHT 480 /*starting window pixel height*/

/*Prototypes or procedures for window and pixel format*/
LONG WINAPI MainWndProc (HWND, UINT, WPARAM, LPARAM);
BOOL bSetupPixelFormat(HDC);

/* O P E N GL G L O B A L S, D E F I N E S A N D P R O T O T Y P E S */
/*OpenGL globals*/
GLfloat cylinderDiam, cylinderHeight, diaminc, heightinc;
GLdouble radius;

/*OpenGL defines*/
#define CYLINDER 1 /*The object to be rendered*/

/*OpenGL prototypes or functions*/
GLvoid resize(GLsizei, GLsizei);
GLvoid initializeGL(GLsizei, GLsizei);
GLvoid drawScene(GLvoid);
void endCylinderView( GLdouble, GLdouble, GLdouble, GLdouble);



/* R E G I S T E R F R A M E C L A S S A N D C R E A T E A S W I N D O W */

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
MSG msg;
WNDCLASS wndclass;

/* Register the frame class */
wndclass.style = 0;
wndclass.lpfnWndProc = (WNDPROC)MainWndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon (hInstance, szAppName);
wndclass.hCursor = LoadCursor (NULL,IDC_ARROW);
wndclass.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wndclass.lpszMenuName = szAppName;
wndclass.lpszClassName = szAppName;

if (!RegisterClass (&wndclass) )
return FALSE;

/* Create the frame */
ghWnd = CreateWindow (szAppName,
"CYLINDER VER 0.0001",
WS_OVERLAPPEDWINDOW | WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
CW_USEDEFAULT,
CW_USEDEFAULT,
WIDTH,
HEIGHT,
NULL,
NULL,
hInstance,
NULL);

/* make sure window was created */
if (!ghWnd)
return FALSE;

/* show and update main window */
ShowWindow (ghWnd, nCmdShow);

UpdateWindow (ghWnd);

/* animation loop */
while (1) {
/*
* Process all pending messages
*/

while (PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE) == TRUE)
{
if (GetMessage(&msg, NULL, 0, 0) )
{
TranslateMessage(&msg);
DispatchMessage(&msg);
} else {
return TRUE;
}
}
drawScene();
}
}


/* W I N 32 A P I W I N D O W´ s G E T D E V I C E C O N T E X T */
/* I T´ S R E N D E R I N G C O N T E X T */
/* A N D U S E R K E Y B O A R D R O U T I N E S */
/* main window procedure */
LONG WINAPI MainWndProc (
HWND hWnd, /*handle for our window */
UINT uMsg, /*messages*/
WPARAM wParam,
LPARAM lParam)
{
LONG lRet = 1;
PAINTSTRUCT ps;
RECT rect;

switch (uMsg) {

/*Win procedural call to get device context with window´s handle*/
/*Win procedural call to get render context concurrent with device context*/
case WM_CREATE:
ghDC = GetDC(hWnd);
if (!bSetupPixelFormat(ghDC))
PostQuitMessage (0);

ghRC = wglCreateContext(ghDC);
wglMakeCurrent(ghDC, ghRC);
GetClientRect(hWnd, &rect);
initializeGL(rect.right, rect.bottom);
break;

/*Win32 Api Paint*/
case WM_PAINT:
BeginPaint(hWnd, &ps);
EndPaint(hWnd, &ps);
break;
/*Win32 Api window´s size*/
case WM_SIZE:
GetClientRect(hWnd, &rect);
resize(rect.right, rect.bottom);
break;

/*Win32 Api to close window and reset render and device context to zero*/
case WM_CLOSE:
if (ghRC)
wglDeleteContext(ghRC);
if (ghDC)
ReleaseDC(hWnd, ghDC);
ghRC = 0;
ghDC = 0;

DestroyWindow (hWnd);
break;

/*Win32 Api to destroy window and delete render and device context*/
case WM_DESTROY:
if (ghRC)
wglDeleteContext(ghRC);
if (ghDC)
ReleaseDC(hWnd, ghDC);
PostQuitMessage (0);
break;

/*User controlled Kyboard routines*/
case WM_KEYDOWN:
switch (wParam) {
case VK_LEFT:
diaminc += 0.2F;
break;
case VK_RIGHT:
diaminc -= 0.2F;
break;
case VK_UP:
heightinc += 0.2F;
break;
case VK_DOWN:
heightinc -= 0.2F;
break;
}
/* Windows procedure for messages*/
default:
lRet = DefWindowProc (hWnd, uMsg, wParam, lParam);
break;
}

return lRet;
}

/* D E T E R M I N A T I O N O F D E P T H A N D P I X E L F O R M A T*/

BOOL bSetupPixelFormat(HDC hdc)
{
PIXELFORMATDESCRIPTOR pfd, *ppfd;
int pixelformat;

ppfd = &pfd;

ppfd->nSize = sizeof(PIXELFORMATDESCRIPTOR);
ppfd->nVersion = 1;
ppfd->dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER;
ppfd->dwLayerMask = PFD_MAIN_PLANE;
ppfd->iPixelType = PFD_TYPE_COLORINDEX;
ppfd->cColorBits = 8;
ppfd->cDepthBits = 16;
ppfd->cAccumBits = 0;
ppfd->cStencilBits = 0;

pixelformat = ChoosePixelFormat(hdc, ppfd);

if ( (pixelformat = ChoosePixelFormat(hdc, ppfd)) == 0 )
{
MessageBox(NULL, "ChoosePixelFormat failed", "Error", MB_OK);
return FALSE;
}

if (SetPixelFormat(hdc, pixelformat, ppfd) == FALSE)
{
MessageBox(NULL, "SetPixelFormat failed", "Error", MB_OK);
return FALSE;
}

return TRUE;
}


/* O P E N GL R E S I Z E A N D P R O J E C T I O N T R A N S F O R M S*/
GLvoid resize( GLsizei width, GLsizei height )
{
GLfloat aspect;

glViewport( 0, 0, width, height );

aspect = (GLfloat) width / height;

glMatrixMode( GL_PROJECTION );
glLoadIdentity();
gluPerspective( 45.0, aspect, 3.0, 7.0 );
glMatrixMode( GL_MODELVIEW );
}

/*SCENE SETUP*/

/* Object creation */
GLvoid createObjects()
{
GLUquadricObj *quadObj;

glNewList(CYLINDER, GL_COMPILE);
quadObj = gluNewQuadric ();
gluQuadricDrawStyle (quadObj, GLU_FILL);
gluQuadricNormals (quadObj, GLU_SMOOTH);
gluCylinder (quadObj, 0.3, 0.3, 0.6, 12, 2);
glEndList();

}

/* Function Initialize Scene objects */
GLvoid initializeGL(GLsizei width, GLsizei height)
{
GLfloat maxObjectSize, aspect;
GLdouble near_plane, far_plane;

/* Initial depth and background */
glClearIndex( (GLfloat)BLACK_INDEX);
glClearDepth( 1.0 );

/* Initial depth test */
glEnable(GL_DEPTH_TEST);

glMatrixMode( GL_PROJECTION );
aspect = (GLfloat) width / height;
gluPerspective( 45.0, aspect, 3.0, 7.0 );
glMatrixMode( GL_MODELVIEW );

near_plane = 3.0;
far_plane = 12.0;
maxObjectSize = 3.0F;
radius = near_plane + maxObjectSize/2.0;

cylinderDiam = 0.0F;
cylinderHeight = 0.0F;
diaminc = 3.0F;
heightinc = 0.0F;

createObjects();
}


/*Set model transform for object (i) using glTranslatef, glScalef, glRotatef, and/or equivalent.*/
void endCylinderView(GLdouble radius, GLdouble twist, GLdouble cylinderDiam,
GLdouble cylinderHeight)
{
glTranslated(0.0, 0.0, -radius);
glRotated(-twist, 0.0, 0.0, 1.0);
glRotated(-cylinderDiam, 1.0, 0.0, 0.0);
glRotated(cylinderHeight, 0.0, 0.0, 1.0);

}

/* O P E N GL R E F R E S H */

/* Final Function to Draw current scene objects, ect */

GLvoid drawScene(GLvoid)
{
/*Clear previous frame depth and color buffer enabling next frame*/
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );

/*access OpenGl´s matrix stack to save transformations*/
glPushMatrix();

/*User´s Kayboard values*/
cylinderDiam += diaminc*.5;
cylinderHeight += heightinc*.5;

/*Call to object´s function with current values*/
endCylinderView(radius, 0, cylinderDiam, cylinderHeight);

/* Final Call for Objects to be rendered*/
glIndexi(RED_INDEX);
glCallList(CYLINDER);

/*restore OpenGl´s matrix stack transformations to continue to translatef*/
glPopMatrix();

/* Make scene visible */
SWAPBUFFERS;
}

oops double post!

[Silkut]

cylinder from scratch ? what's this ? Can someone explain me ? :)

If you want to make a cylinder, you can use the quadratic solution, check http://nehe.gamedev.net