OpenGL, draw two polygons in the same time (by mouse clicks)
- by YoungSalafi
im trying to draw 2 polygons at the same time depending on user input from the opengl screen... so i made 2 arrays which each one of them will carry the vertices of each polygon ... i think my logic is right but the program still prints only polygon and delete the old polygon if you draw a polygon again . and its acting weird too please check the code yourself here it is :
P.S dont mind the delete function right now.. i know it missing something.
#include <windows.h>
#include <gl/gl.h>
#include <gl/glut.h>
void Draw();
void Set_Transformations();
void Initialize(int argc, char *argv[]);
void OnKeyPress(unsigned char key, int x, int y);
void DeleteVer();
void MouseClick(int bin, int state , int x , int y);
void GetOGLPos(int x, int y,float* arrY,float* arrX);
void DrawPolygon(float* arrX,float* arrY);
float xPos[20];
float yPos[20];
float xPos2[20];
float yPos2[20];
float fx = 0,fy = 0;
float size = 10;
int count = 0;
bool done = false;
bool flag = true;
void Initialize(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA);
glutInitWindowPosition(100, 100);
glutInitWindowSize(600, 600);
glutCreateWindow("OpenGL Lab1");
Set_Transformations();
glutDisplayFunc(Draw);
glutMouseFunc(MouseClick);
glutKeyboardFunc(OnKeyPress);
glutMainLoop();
}
void Set_Transformations()
{
glClearColor(1, 1, 1, 1);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(-200, 200, -200, 200);
}
void OnKeyPress(unsigned char key, int x, int y)
{
if (key == 27)
exit(0);
switch(key)
{
case 13: //enter key it will draw
done = true;
glutPostRedisplay();
flag=!flag; // this flag to switch to the other array that the vertices will be stored in, in order to draw the second polygon
break;
}
}
void MouseClick(int button, int state , int x , int y)
{
switch (button)
{
case GLUT_RIGHT_BUTTON:
if (state == GLUT_DOWN)
{
if (count>0)
{
DeleteVer(); //dont mind this right now
}
}
break;
case GLUT_LEFT_BUTTON:
if (state == GLUT_DOWN)
{
if(count<20)
{
if(flag =true){ // drawing first polygon
GetOGLPos(x, y,xPos,yPos);}
if (flag=false) //drawing second polygon after Enter is pressed
GetOGLPos(x, y,xPos2,yPos2);
}
}
break;
}
}
void GetOGLPos(int x, int y,float* arrY,float* arrX) //getting the vertices from the user
{
GLint viewport[4];
GLdouble modelview[16];
GLdouble projection[16];
GLfloat winX, winY, winZ;
GLdouble posX, posY, posZ;
glGetDoublev( GL_MODELVIEW_MATRIX, modelview );
glGetDoublev( GL_PROJECTION_MATRIX, projection );
glGetIntegerv( GL_VIEWPORT, viewport );
winX = (float)x;
winY = (float)viewport[3] - (float)y;
glReadPixels( x, int(winY), 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ );
gluUnProject( winX, winY, winZ, modelview, projection, viewport, &posX, &posY, &posZ);
arrX[count] = posX;
arrY[count] = posY;
count++;
glPointSize( 6.0 );
glBegin(GL_POINTS);
glVertex2f(posX,posY);
glEnd();
glFlush();
}
void DeleteVer(){ //dont mind this
glColor3f ( 1, 1, 1);
glBegin(GL_POINTS);
glVertex2f(xPos[count-1],yPos[count-1]);
glEnd();
glFlush();
xPos[count] = NULL;
yPos[count] = NULL;
count--;
glColor3f ( 0, 0, 0);
}
void DrawPolygon(float* arrX,float* arrY)
{
int n=0;
glColor3f ( 0, 0, 0);
glBegin(GL_POLYGON);
while(n<count)
{
glVertex2f(arrX[n],arrY[n]);
n++;
}
count=0;
glEnd();
glFlush();
}
void Draw() //main drawing func
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(0, 0, 0);
if(done)
{
DrawPolygon(xPos,yPos);
DrawPolygon(xPos2,yPos2);
}
glFlush();
}
int main(int argc, char *argv[])
{
Initialize(argc, argv);
return 0;
}
