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/************************************************************************
Handy functions for common OpenGL tasks
$Id: gltools.cxx 446 2005-06-18 13:58:15Z garland $
************************************************************************/
#include <gfx/gfx.h>
#ifdef HAVE_OPENGL
#include <gfx/gltools.h>
#include <cassert>
namespace gfx
{
using std::cerr;
using std::endl;
GLuint opengl_pick_nil = (~0);
GLuint opengl_pick_zmax = (~0);
void begin_opengl_pick(int *where, double radius, GLuint *buffer, int size)
{
GLint vp[4];
glGetIntegerv(GL_VIEWPORT, vp);
glSelectBuffer(size, buffer);
glRenderMode(GL_SELECT);
glInitNames();
glPushName(opengl_pick_nil);
glMatrixMode(GL_PROJECTION);
glPushMatrix(); // Save the current transformation
glLoadIdentity();
gluPickMatrix(where[0], vp[3] - where[1], radius, radius, vp);
}
GLuint complete_opengl_pick(GLuint *buffer)
{
glMatrixMode(GL_PROJECTION);
glPopMatrix(); // get rid of the pick matrix
glFlush();
GLint nhits = glRenderMode(GL_RENDER);
GLuint *hit = NULL;
GLuint hit_nnames = 0;
GLuint zmin = opengl_pick_zmax;
GLuint *ptr = buffer;
for(int i=0; i<nhits; i++)
{
GLuint nnames = *ptr++;
GLuint cur_zmin = *ptr++;
/* GLuint cur_zmax = */ *ptr++;
if( cur_zmin < zmin )
{
zmin = cur_zmin;
hit = ptr;
hit_nnames = nnames;
}
ptr+=nnames;
}
buffer[0] = hit_nnames;
if( hit )
{
for(int k=0; k<hit_nnames; k++)
buffer[k+1] = hit[k];
return *hit;
}
else
return opengl_pick_nil;
}
void report_opengl_stacks()
{
GLint depth;
glGetIntegerv(GL_PROJECTION_STACK_DEPTH, &depth);
cerr << " Projection stack depth = " << depth;
glGetIntegerv(GL_MAX_PROJECTION_STACK_DEPTH, &depth);
cerr << " (" << depth << " max)" << endl;
glGetIntegerv(GL_MODELVIEW_STACK_DEPTH, &depth);
cerr << " ModelView stack depth = " << depth;
glGetIntegerv(GL_MAX_MODELVIEW_STACK_DEPTH, &depth);
cerr << " (" << depth << " max)" << endl;
glGetIntegerv(GL_TEXTURE_STACK_DEPTH, &depth);
cerr << " Texture stack depth = " << depth;
glGetIntegerv(GL_MAX_TEXTURE_STACK_DEPTH, &depth);
cerr << " (" << depth << " max)" << endl;
}
void check_opengl_errors(const char *msg)
{
bool stack_error = false;
for(GLenum err=glGetError(); err!=GL_NO_ERROR; err=glGetError())
{
cerr << "GL ERROR ";
if( msg ) cerr << msg;
cerr << ": " << (const char *)gluErrorString(err) << endl;
if( err==GL_STACK_OVERFLOW || err==GL_STACK_UNDERFLOW )
stack_error = true;
}
if( stack_error ) report_opengl_stacks();
}
void camera_lookat(const Vec3& min, const Vec3& max, double aspect)
{
Vec3 up(0, 1, 0);
double fovy = 60.0;
Vec3 at = (max + min)/2.0; // look at the center of the bbox
double radius = norm(max - at); // radius of a bounding sphere
double d = 3*radius / tan(fovy * M_PI/180.0);
Vec3 from = at;
from[2] += d;
double znear = d/20;
double zfar = 10*d;
glMatrixMode(GL_PROJECTION);
gluPerspective(fovy, aspect, znear, zfar);
glMatrixMode(GL_MODELVIEW);
gluLookAt(from[0], from[1], from[2],
at[0], at[1], at[2],
up[0], up[1], up[2]);
}
void ortho_camera_lookat(const Vec3& min, const Vec3& max, double aspect)
{
Vec3 up(0, 1, 0);
double fovy = 60.0;
Vec3 at = (max + min)/2.0; // look at the center of the bbox
double radius = norm(max - at); // radius of a bounding sphere
double d = 3*radius / tan(fovy * M_PI/180.0);
Vec3 from = at;
from[2] += d;
Vec3 diag = max-min;
double width = MAX(diag[0], diag[1]); width=MAX(width, diag[2]);
width *= 1.1;
double znear = d/20;
double zfar = 10*d;
glMatrixMode(GL_PROJECTION);
glOrtho(-aspect/2*width, aspect/2*width, -0.5*width, 0.5*width, znear, zfar);
glMatrixMode(GL_MODELVIEW);
gluLookAt(from[0], from[1], from[2],
at[0], at[1], at[2],
up[0], up[1], up[2]);
}
int unproject_pixel(int *pixel, double *world, double z)
{
GLdouble modelMatrix[16];
GLdouble projMatrix[16];
GLint viewport[4];
glGetDoublev(GL_PROJECTION_MATRIX, projMatrix);
glGetDoublev(GL_MODELVIEW_MATRIX, modelMatrix);
glGetIntegerv(GL_VIEWPORT, viewport);
// Notice that we have to correct the y pixel coordinate. GL
// assigns the origin to the lower left corner, while FLTK assigns
// the origin to the upper left corner.
return gluUnProject(pixel[0], viewport[3]-pixel[1], z,
modelMatrix, projMatrix, viewport,
world, world+1, world+2);
}
} // namespace gfx
#endif /* HAVE_OPENGL */
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