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/*
* Draw samples of wide lines, smooth lines and stippled lines in
* all combinations.
*
* Brian Paul
* 13 Feb 2015
*/
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <GL/glew.h> // just for GL_ALIASED_LINE_WIDTH_RANGE
#include "glut_wrap.h"
static int w, h;
static float g, lw = 3.0;
static void
draw_line_sample(GLboolean smooth, GLboolean stipple, GLfloat width)
{
float r0 = 0.4;
float r1 = 0.8;
float r2 = 0.9;
float r3 = 0.95;
int i;
glLineWidth(width);
if (stipple) {
glEnable(GL_LINE_STIPPLE);
}
else {
glDisable(GL_LINE_STIPPLE);
}
if (smooth) {
glEnable(GL_LINE_SMOOTH);
glEnable(GL_BLEND);
}
else {
glDisable(GL_LINE_SMOOTH);
glDisable(GL_BLEND);
}
/* spokes */
glBegin(GL_LINES);
for (i = 0; i < 360; i += 10) {
float x0 = r0 * cos(i * M_PI / 180.0);
float y0 = r0 * sin(i * M_PI / 180.0);
float x1 = r1 * cos(i * M_PI / 180.0);
float y1 = r1 * sin(i * M_PI / 180.0);
glVertex2f(x0, y0);
glVertex2f(x1, y1);
}
glEnd();
/* circle */
glBegin(GL_LINE_STRIP);
for (i = 0; i <= 360; i += 10) {
float x = r2 * cos(i * M_PI / 180.0);
float y = r2 * sin(i * M_PI / 180.0);
glVertex2f(x, y);
}
glEnd();
/* box */
glBegin(GL_LINE_STRIP);
glVertex2f(-r3, -r3);
glVertex2f( r3, -r3);
glVertex2f( r3, r3);
glVertex2f(-r3, r3);
glVertex2f(-r3, -r3);
glEnd();
}
static void
Init(void)
{
GLfloat range[2];
char title[1000];
printf("GL_RENDERER = %s\n", (const char *) glGetString(GL_RENDERER));
printf("GL_VERSION = %s\n", (const char *) glGetString(GL_VERSION));
glGetFloatv(GL_ALIASED_LINE_WIDTH_RANGE, range);
printf("Aliased line width range %.5f .. %.5f\n", range[0], range[1]);
glGetFloatv(GL_LINE_WIDTH_RANGE, range);
printf("Smooth line width range %.5f .. %.5f\n", range[0], range[1]);
glGetFloatv(GL_LINE_WIDTH_GRANULARITY, &g);
printf("line width granularity %f\n", g);
fflush(stdout);
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glBlendFunc(GL_SRC_ALPHA, GL_ONE);
/* pattern: |- -- --- ---- | */
glLineStipple(2, 0x1eed);
sprintf(title, "Line Sampler (%s)", (const char *) glGetString(GL_RENDERER));
glutSetWindowTitle(title);
}
static void
Draw(void)
{
int i;
glClear(GL_COLOR_BUFFER_BIT);
for (i = 0; i < 2; i++) {
float width = i ? lw : 1.0;
glViewport(0*w, i*h, w, h);
draw_line_sample(GL_FALSE, GL_FALSE, width);
glViewport(1*w, i*h, w, h);
draw_line_sample(GL_TRUE, GL_FALSE, width);
glViewport(2*w, i*h, w, h);
draw_line_sample(GL_FALSE, GL_TRUE, width);
glViewport(3*w, i*h, w, h);
draw_line_sample(GL_TRUE, GL_TRUE, width);
}
glutSwapBuffers();
}
static void
Reshape(int width, int height)
{
w = width / 4;
h = height / 2;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
static void
Key(unsigned char key, int x, int y)
{
if (key == 'w') {
lw -= g;
if (lw < g)
lw = g;
}
else if (key == 'W') {
lw += g;
}
if (key == 27)
exit(0);
printf("line width %.5f\n", lw);
fflush(stdout);
glutPostRedisplay();
}
int
main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitWindowPosition(0, 0);
glutInitWindowSize(1000, 500);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
if (!glutCreateWindow("Line Sampler")) {
exit(1);
}
Init();
glutReshapeFunc(Reshape);
glutKeyboardFunc(Key);
glutDisplayFunc(Draw);
glutMainLoop();
return 0;
}
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