First of all: hi everyone
I got some (maybe easy) questions for you and i hope someone will be so gentle and answer them. I started some days ago with opengl and i am using the ide Dev-C (i started c++ with it). Can you recommend me a âbetterâ one (freeware and windows ?).
I started with a program, which moves balls and let them bounce in a square around. The first problem is, that the moving balls are giving me a graphic failure (see the pic below):
http://img703.imageshack.us/i/probv.jpg/
Code for the Ball-drawing:
void circle(float center_y, float center_x, float z, float radius) {
float x = 0.0f;
float y = 0.0f;
glBegin(GL_POLYGON);
for( double theta = 0.0; theta <= (2*M_PI); theta += ((M_PI) / 180.0) ) {
y = center_y + ( sin( theta ) * radius );
x = center_x + ( cos( theta ) * radius );
glVertex3f( x, y, z );
}
glEnd();
}
I tried to draw the ball in two halfsides, to vary the drawing angle (M_PI) - why do i get these drawing faults?
I added the whole code down. Red is the circle stuff and blue the moving-the-ball-part.
I also attached the files.
The other question is:
The program is not quite âfastâ. I expected it to be faster such as adding a delay to slow it down. As i know the screen is redrawn with the command âSwapBuffers (hDC);â.
I am just concerned because if i want to create more complex stuff this will not work so. If i am doing a big mistake please tell me.
regards
claus
#include <windows.h>
#include <gl/gl.h>
#include <cmath>
#include <ctime>
LRESULT CALLBACK WndProc (HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam);
void EnableOpenGL (HWND hWnd, HDC *hDC, HGLRC *hRC);
void DisableOpenGL (HWND hWnd, HDC hDC, HGLRC hRC);
void circle(float center_y, float center_x, float z, float radius) {
float x = 0.0f;
float y = 0.0f;
glBegin(GL_POLYGON);
for( double theta = 0.0; theta <= (2*M_PI); theta += ((M_PI) / 180.0) ) {
y = center_y + ( sin( theta ) * radius );
x = center_x + ( cos( theta ) * radius );
glVertex3f( x, y, z );
}
glEnd();
}
double zufall(float r_wert, float o_grenze, float u_grenze)
{
int r1,r2,r3 = 0;
double r4,r5,r6;
time_t t;
time(&t);
// srand((unsigned int)t);
while (r6 < u_grenze or r6 > o_grenze or r3 == 0) {
r1 = rand() % 1000 + 1;
r2 = rand() % 1000 + 1;
r4 = (double) r1;
r5 = (double) r2;
r3 = (rand() % 3 - 1);
r6 = (r4/(r5*r_wert))*r3;
}
return(r6);
}
int WINAPI WinMain (HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int iCmdShow)
{
WNDCLASS wc;
float theta = 0.0f;
HWND hWnd;
HDC hDC;
HGLRC hRC;
MSG msg;
BOOL bQuit = FALSE;
wc.style = CS_OWNDC;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor (NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) GetStockObject (BLACK_BRUSH);
wc.lpszMenuName = NULL;
wc.lpszClassName = "GLSample";
RegisterClass (&wc);
hWnd = CreateWindow (
"GLSample", "OpenGL Sample",
WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE,
0, 0, 500, 500,
NULL, NULL, hInstance, NULL);
EnableOpenGL (hWnd, &hDC, &hRC);
float z1=1,z2=0.95,b=0.015;
int anzahl = 2;
float rx[anzahl];
float ry[anzahl];
float x[anzahl];
float y[anzahl];
int i;
for (i;i<anzahl;i++)
{
x[i] = zufall(0.1, 1, -1);
y[i] = zufall(0.1, 1, -1);
rx[i] = zufall(100, 0.5, -0.5);
ry[i] = zufall(100, 0.5, -0.5);
}
i = 1;
float gr = 0.025;
float grenze = 0.86, lgrenze = 0.9;
glColor3f( 1.0f, 1.0f, 1.0f );
glBegin(GL_LINES);
glVertex3f( lgrenze, lgrenze, 0.0);
glVertex3f( -lgrenze,lgrenze, 0.0);
glVertex3f( -lgrenze, -lgrenze, 0.0);
glVertex3f( lgrenze, -lgrenze, 0.0);
glVertex3f( -lgrenze, -lgrenze, 0.0);
glVertex3f( -lgrenze, lgrenze, 0.0);
glVertex3f( lgrenze, lgrenze, 0.0);
glVertex3f( lgrenze, -lgrenze, 0.0);
glEnd();
SwapBuffers (hDC);
while (!bQuit)
{
if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
{
if (msg.message == WM_QUIT)
{
bQuit = TRUE;
}
else
{
TranslateMessage (&msg);
DispatchMessage (&msg);
}
}
else
{
/* glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
glClear (GL_COLOR_BUFFER_BIT);
glPushMatrix ();
glRotatef (theta, 0.0f, 0.0f, 1.0f);
*/
/*
glBegin(GL_TRIANGLES);
glColor4f(1.0f, 0.0f, 0.0f, 1.0f); // Rot
glVertex2f(0.50f, 0.50f);
glColor4f(0.0f, 1.0f, 0.0f, 1.0f); // GrĂźn
glVertex2f(0.0f, 0.50f);
glColor4f(0.0f, 0.0f, 1.0f, 1.0f); // Blau
glVertex2f(0.50f, -0.50f);
glColor4f(1.0f, 0.0f, 0.0f, 1.0f); // Rot
glVertex2f(-0.50f, -0.50f);
glColor4f(0.0f, 1.0f, 0.0f, 1.0f); // GrĂźn
glVertex2f(-0.1f, -0.10f);
glColor4f(0.0f, 0.0f, 1.0f, 1.0f); // Blau
glVertex2f(0.50f, -0.50f);
glEnd();
*/
// glColor3f (1, 1, 1);
// glPointSize (10);
// glBegin (GL_POINTS);
[b] for (i=0;i<anzahl;i++)
{
if (x[i] >= grenze) rx[i] = -rx[i];
if (y[i] >= grenze) ry[i] = -ry[i];
if (x[i] <= -grenze && rx[i] < 0) rx[i] = -rx[i];
if (y[i] <= -grenze && ry[i] < 0) ry[i] = -ry[i];
glColor3f (0.0, 0.0, 0.0);
circle(y[i], x[i], 0.0, gr);
x[i] = x[i]+rx[i];
y[i] = y[i]+ry[i];
glColor3f (1.0, 1.0, 1.0);
circle(y[i], x[i], 0.0, gr);
}[/b]
// glPopMatrix ();
SwapBuffers (hDC);
// theta += 1.0f;
// Sleep (5);
}
}
DisableOpenGL (hWnd, hDC, hRC);
DestroyWindow (hWnd);
return msg.wParam;
}
LRESULT CALLBACK WndProc (HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
return 0;
case WM_CLOSE:
PostQuitMessage (0);
return 0;
case WM_DESTROY:
return 0;
case WM_KEYDOWN:
switch (wParam)
{
case VK_ESCAPE:
PostQuitMessage(0);
return 0;
}
return 0;
default:
return DefWindowProc (hWnd, message, wParam, lParam);
}
}
void EnableOpenGL (HWND hWnd, HDC *hDC, HGLRC *hRC)
{
PIXELFORMATDESCRIPTOR pfd;
int iFormat;
*hDC = GetDC (hWnd);
ZeroMemory (&pfd, sizeof (pfd));
pfd.nSize = sizeof (pfd);
pfd.nVersion = 1;
pfd.dwFlags = PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
pfd.iPixelType = PFD_TYPE_RGBA;
pfd.cColorBits = 24;
pfd.cDepthBits = 16;
pfd.iLayerType = PFD_MAIN_PLANE;
iFormat = ChoosePixelFormat (*hDC, &pfd);
SetPixelFormat (*hDC, iFormat, &pfd);
*hRC = wglCreateContext( *hDC );
wglMakeCurrent( *hDC, *hRC );
}
void DisableOpenGL (HWND hWnd, HDC hDC, HGLRC hRC)
{
wglMakeCurrent (NULL, NULL);
wglDeleteContext (hRC);
ReleaseDC (hWnd, hDC);
}