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09.18.2008 at 04:00PM PDT, ID: 23744313
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Attachment Details

OpenGL -- "void(move)" function

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9.2
Zones:

OpenGL Graphics & Game Programming, C Programming Language

I'm taking a class in OpenGL.  We've been giving some examples files that required modification.

The program below draws a square.   I've already replaced the "lines" with "square" (mouse function).   I've also modified the "move()" function.    Although the program compiles/builds fine, the move() function doesn't seem to work properly.  

With the commented out move() function, it draws the square but it is using lines.   It is supposed to already draw a square when dragging/moving the mouse.

What am I missing?  

EEH
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#include <stdlib.h>
#include <GL/glut.h>
 
float xm, ym, xmm, ymm;
float width = 500, height = 500;
int first = 0;
 
 
void mouse(int btn, int state, int x, int y)
{
	if (btn == GLUT_LEFT_BUTTON && state == GLUT_DOWN)
	{
		xm = x / width;
		ym = (height - y) / height;
		glColor3f(0.0, 0.0, 1.0);
		glLogicOp(GL_XOR);
		first = 0;
	}
	if (btn == GLUT_LEFT_BUTTON && state == GLUT_UP)
	{
		glRectf(xm, ym, xmm, ymm);
		glFlush();
		glColor3f(0.0, 1.0, 0.0);
		xmm = x / width;
		ymm = (height - y) / height;
		glLogicOp(GL_COPY);
		glRectf(xm, ym, xmm, ymm);
		glFlush();
	}
}
 
void myReshape(int w, int h)
{
   	glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, 1, 0, 1);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
 
   	glViewport(0, 0, w, h);
	width = w; height = h;
}
 
 
 
 
//void move(int x, int y)
//{
//	if (first == 1)
//	{
//		glBegin(GL_LINES);
//			glVertex2f(xm, ym);
//			glVertex2f(xmm, ymm);
//		glEnd();
//		glutSwapBuffers();
//		glFlush();
//	}
//
//	xmm = x / width;
//	ymm = (height - y) / height;
//	glBegin(GL_LINES);
//		glVertex2f(xm, ym);
//		glVertex2f(xmm, ymm);
//	glEnd();
//	glutSwapBuffers ();
//	glFlush();
//	first = 1;
//}
 
 
void move(int x, int y)
{
	if (first == 1)
	{
		glRectf(xm, ym, xmm, ymm);
		glFlush();
	}
	xmm = x / width;
    ymm = (height - y) / height;
	glRectf(xm, ym, xmm, ymm);
	glFlush();
	first = 1;
}
 
 
void myinit() 
{
    glClearColor (0.0, 0.0, 0.0, 1.0);
}
 
/* display callback required by GLUT */
 
void display() 
{
	glClear(GL_COLOR_BUFFER_BIT);
	glutSwapBuffers();
	glFlush();
}
 
int main(int argc, char** argv) 
{
    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
	glutInitWindowPosition(100, 100);
	glutInitWindowSize(width, height);
    glutCreateWindow("Rubberband");
    myinit ();	
	glEnable(GL_COLOR_LOGIC_OP);
    glutReshapeFunc (myReshape);
    glutMouseFunc (mouse);
    glutMotionFunc(move);
    glutDisplayFunc(display);
    glutMainLoop();
}
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Answered By: itsmeandnobodyelse
Expert Since: 10/02/2003
Accepted Solutions: 2581
Computer Expertise: Guru
itsmeandnobodyelse has been an Expert for 5 years 3 months, during which he has posted 11196 comments and answered 2581 questions. itsmeandnobodyelse is just one of 71 experts in the OpenGL Graphics & Game Programming Zone. 1 expert collaborated on this answer, which was graded an "A" by the asker.
 
 
20081119-EE-VQP-47 / EE_QW_2_20070628