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View Full Version : Query on Line Stipple



nagesh
05-21-2015, 08:52 PM
Hi All,

When I was Browsing a example for line stipple I got the following code

#define drawOneLine(x1,y1,x2,y2) glBegin(GL_LINES); \
glVertex2f ((x1),(y1)); glVertex2f ((x2),(y2)); glEnd();

void init(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel (GL_FLAT);
}

void display(void)
{
int i;

glClear (GL_COLOR_BUFFER_BIT);

/* select white for all lines */
glColor3f (1.0, 1.0, 1.0);

/* in 1st row, 3 lines, each with a different stipple */
glEnable (GL_LINE_STIPPLE);

glLineStipple (1, 0x0101); /* dotted */
drawOneLine (50.0, 125.0, 150.0, 125.0);
glLineStipple (1, 0x00FF); /* dashed */
drawOneLine (150.0, 125.0, 250.0, 125.0);
glLineStipple (1, 0x1C47); /* dash/dot/dash */
drawOneLine (250.0, 125.0, 350.0, 125.0);

/* in 2nd row, 3 wide lines, each with different stipple */
glLineWidth (5.0);
glLineStipple (1, 0x0101); /* dotted */
drawOneLine (50.0, 100.0, 150.0, 100.0);
glLineStipple (1, 0x00FF); /* dashed */
drawOneLine (150.0, 100.0, 250.0, 100.0);
glLineStipple (1, 0x1C47); /* dash/dot/dash */
drawOneLine (250.0, 100.0, 350.0, 100.0);
glLineWidth (1.0);

/* in 3rd row, 6 lines, with dash/dot/dash stipple */
/* as part of a single connected line strip */
glLineStipple (1, 0x1C47); /* dash/dot/dash */
glBegin (GL_LINE_STRIP);
for (i = 0; i < 7; i++)
glVertex2f (50.0 + ((GLfloat) i * 50.0), 75.0);
glEnd ();

/* in 4th row, 6 independent lines with same stipple */
for (i = 0; i < 6; i++) {
drawOneLine (50.0 + ((GLfloat) i * 50.0), 50.0,
50.0 + ((GLfloat)(i+1) * 50.0), 50.0);
}

/* in 5th row, 1 line, with dash/dot/dash stipple */
/* and a stipple repeat factor of 5 */
glLineStipple (5, 0x1C47); /* dash/dot/dash */
drawOneLine (50.0, 25.0, 350.0, 25.0);

glDisable (GL_LINE_STIPPLE);
glFlush ();
}

void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);
}

with the output as shown in figure 1....


But when the same code is executed in OPENGL the out was different and it was as shown in figure2....


Which output is correct????