Attached is a test program that renders an indexed GL_LINES
primitive using both glDrawElements and glDrawRangeElements
(selected by pressing the 'v' key). There seems to be a
problem with glDrawRangeElements when the (min, max) range is
(0, 1) and I am only drawing one line. If I increase the max
range it seems to have no problem (even though I am still only
rendering the first line.
scott
P.S. Happy New Year everyone.
--
Scott McMillan mailto:[EMAIL PROTECTED]
Cambridge Research Associates http://www.cambridge.com
1430 Spring Hill Road, Ste. 200 Voice: (703) 790-0505 x7235
McLean, VA 22102 Fax: (703) 790-0370
#include <GL/gl.h>
#include <GL/glu.h>
#include <GL/glut.h>
#include <stdio.h>
#include <stdlib.h>
int vertex_arrays_flag = 1;
GLfloat vertices[8][3] = {{-3, 1, -10},
{-3,-1, -10},
{-1, 1, -10},
{-1,-1, -10},
{ 1, 1, -10},
{ 1,-1, -10},
{ 3, 1, -10},
{ 3,-1, -10}};
unsigned int indices[8] = {0,1,2,3,4,5,6,7};
void init(void)
{
glClearColor(0.0, 0.0, 0.0, 0.0);
glPolygonMode(GL_FRONT, GL_LINE);
}
float num = 3.0;
void display(void)
{
int i;
glClear(GL_COLOR_BUFFER_BIT);
if (vertex_arrays_flag == 1)
{
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glDrawRangeElements(GL_LINES,
0,
1, /* HERE: Change this to 7 and things work */
2, GL_UNSIGNED_INT, indices);
glDisableClientState(GL_VERTEX_ARRAY);
}
else
{
glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glDrawElements(GL_LINES, 2, GL_UNSIGNED_INT, indices);
glDisableClientState(GL_VERTEX_ARRAY);
}
glutSwapBuffers();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, (GLfloat)w/(GLfloat)h, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void keyboard(unsigned char key, int x, int y)
{
switch (key)
{
case 27:
exit(0);
break;
case 'v':
vertex_arrays_flag = 1 - vertex_arrays_flag;
fprintf(stderr, "Using glDrawRangeElements: %d\n",
vertex_arrays_flag);
break;
}
}
int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(500,500);
glutInitWindowPosition(50,50);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(display);
glutIdleFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();
return 0;
}
