void Camera3D::draw_gl ()
{
Vector3DF pnt;
int va, vb;
if ( !mOps[0] ) return;
// Box testing
//
// NOTES: This demonstrates AABB box testing against the frustum
// Boxes tested are 10x10x10 size, spaced apart from each other so we can see them.
if ( mOps[5] ) {
glPushMatrix ();
glEnable ( GL_LIGHTING );
glColor3f ( 1, 1, 1 );
Vector3DF bmin, bmax, vmin, vmax;
int lod;
for (float y=0; y < 100; y += 10.0 ) {
for (float z=-100; z < 100; z += 10.0 ) {
for (float x=-100; x < 100; x += 10.0 ) {
bmin.Set ( x, y, z );
bmax.Set ( x+8, y+8, z+8 );
if ( boxInFrustum ( bmin, bmax ) ) {
lod = (int) calculateLOD ( bmin, 1, 5, 300.0 );
//rendGL->drawCube ( bmin, bmax, Vector3DF(1,1,1) );
}
}
}
}
glPopMatrix ();
}
glDisable ( GL_LIGHTING );
glLoadMatrixf ( getViewMatrix().GetDataF() );
// Frustum planes (world space)
//
// NOTE: The frustum planes are drawn as discs because
// they are boundless (infinite). The minimum information contained in the
// plane equation is normal direction and distance from plane to origin.
// This sufficiently defines infinite planes for inside/outside testing,
// but cannot be used to draw the view frustum without more information.
// Drawing is done as discs here to verify the frustum plane equations.
if ( mOps[2] ) {
glBegin ( GL_POINTS );
glColor3f ( 1, 1, 0 );
Vector3DF norm;
Vector3DF side, up;
for (int n=0; n < 6; n++ ) {
norm.Set ( frustum[n][0], frustum[n][1], frustum[n][2] );
glColor3f ( n/6.0, 1.0- (n/6.0), 0.5 );
side = Vector3DF(0,1,0); side.Cross ( norm ); side.Normalize ();
up = side; up.Cross ( norm ); up.Normalize();
norm *= frustum[n][3];
for (float y=-50; y < 50; y += 1.0 ) {
for (float x=-50; x < 50; x += 1.0 ) {
if ( x*x+y*y < 1000 ) {
//pnt = side * x + up * y - norm;
pnt = side;
Vector3DF tv = up;
tv *= y;
pnt *= x;
pnt += tv;
pnt -= norm;
glVertex3f ( pnt.x, pnt.y, pnt.z );
}
}
}
}
glEnd ();
}
// Inside/outside testing
//
// NOTES: This code demonstrates frustum clipping
// tests on individual points.
if ( mOps[4] ) {
glColor3f ( 1, 1, 1 );
glBegin ( GL_POINTS );
for (float z=-100; z < 100; z += 4.0 ) {
for (float y=0; y < 100; y += 4.0 ) {
for (float x=-100; x < 100; x += 4.0 ) {
if ( pointInFrustum ( x, y, z) ) {
glVertex3f ( x, y, z );
}
}
}
}
glEnd ();
}
// Inverse rays (world space)
//
// NOTES: This code demonstrates drawing
// inverse camera rays, as might be needed for raytracing or hit testing.
if ( mOps[3] ) {
glBegin ( GL_LINES );
glColor3f ( 0, 1, 0);
for (float x = 0; x <= 1.0; x+= 0.5 ) {
for (float y = 0; y <= 1.0; y+= 0.5 ) {
pnt = inverseRay ( x, y, mFar );
pnt += from_pos;
glVertex3f ( from_pos.x, from_pos.y, from_pos.z ); // all inverse rays originate at the camera center
glVertex3f ( pnt.x, pnt.y, pnt.z );
}
}
glEnd ();
}
// Projection
//
// NOTES: This code demonstrates
// perspective projection _without_ using the OpenGL pipeline.
// Projection is done by the camera class. A cube is drawn on the near plane.
// Cube geometry
Vector3DF pnts[8];
Vector3DI edge[12];
pnts[0].Set ( 0, 0, 0 ); pnts[1].Set ( 10, 0, 0 ); pnts[2].Set ( 10, 0, 10 ); pnts[3].Set ( 0, 0, 10 ); // lower points (y=0)
pnts[4].Set ( 0, 10, 0 ); pnts[5].Set ( 10, 10, 0 ); pnts[6].Set ( 10, 10, 10 ); pnts[7].Set ( 0, 10, 10 ); // upper points (y=10)
edge[0].Set ( 0, 1, 0 ); edge[1].Set ( 1, 2, 0 ); edge[2].Set ( 2, 3, 0 ); edge[3].Set ( 3, 0, 0 ); // 4 lower edges
edge[4].Set ( 4, 5, 0 ); edge[5].Set ( 5, 6, 0 ); edge[6].Set ( 6, 7, 0 ); edge[7].Set ( 7, 4, 0 ); // 4 upper edges
edge[8].Set ( 0, 4, 0 ); edge[9].Set ( 1, 5, 0 ); edge[10].Set ( 2, 6, 0 ); edge[11].Set ( 3, 7, 0 ); // 4 vertical edges
// -- White cube is drawn using OpenGL projection
if ( mOps[6] ) {
glBegin ( GL_LINES );
glColor3f ( 1, 1, 1);
for (int e = 0; e < 12; e++ ) {
va = edge[e].x;
vb = edge[e].y;
glVertex3f ( pnts[va].x, pnts[va].y, pnts[va].z );
glVertex3f ( pnts[vb].x, pnts[vb].y, pnts[vb].z );
}
glEnd ();
}
//---- Draw the following in camera space..
// NOTES:
// The remainder drawing steps are done in
// camera space. This is done by multiplying by the
// inverse_rotation matrix, which transforms from camera to world space.
// The camera axes, near, and far planes can now be drawn in camera space.
glPushMatrix ();
glLoadMatrixf ( getViewMatrix().GetDataF() );
glTranslatef ( from_pos.x, from_pos.y, from_pos.z );
glMultMatrixf ( invrot_matrix.GetDataF() ); // camera space --to--> world space
// -- Red cube is drawn on the near plane using software projection pipeline. See Camera3D::project
if ( mOps[6] ) {
glBegin ( GL_LINES );
glColor3f ( 1, 0, 0);
Vector4DF proja, projb;
for (int e = 0; e < 12; e++ ) {
va = edge[e].x;
vb = edge[e].y;
proja = project ( pnts[va] );
projb = project ( pnts[vb] );
if ( proja.w > 0 && projb.w > 0 && proja.w < 1 && projb.w < 1) { // Very simple Z clipping (try commenting this out and see what happens)
glVertex3f ( proja.x, proja.y, proja.z );
glVertex3f ( projb.x, projb.y, projb.z );
}
}
glEnd ();
}
// Camera axes
glBegin ( GL_LINES );
float to_d = (from_pos - to_pos).Length();
glColor3f ( .8,.8,.8); glVertex3f ( 0, 0, 0 ); glVertex3f ( 0, 0, -to_d );
glColor3f ( 1,0,0); glVertex3f ( 0, 0, 0 ); glVertex3f ( 10, 0, 0 );
glColor3f ( 0,1,0); glVertex3f ( 0, 0, 0 ); glVertex3f ( 0, 10, 0 );
glColor3f ( 0,0,1); glVertex3f ( 0, 0, 0 ); glVertex3f ( 0, 0, 10 );
glEnd ();
if ( mOps[1] ) {
// Near plane
float sy = tan ( mFov * DEGtoRAD / 2.0);
float sx = sy * mAspect;
glColor3f ( 0.8, 0.8, 0.8 );
glBegin ( GL_LINE_LOOP );
glVertex3f ( -mNear*sx, mNear*sy, -mNear );
glVertex3f ( mNear*sx, mNear*sy, -mNear );
glVertex3f ( mNear*sx, -mNear*sy, -mNear );
glVertex3f ( -mNear*sx, -mNear*sy, -mNear );
glEnd ();
// Far plane
glBegin ( GL_LINE_LOOP );
glVertex3f ( -mFar*sx, mFar*sy, -mFar );
glVertex3f ( mFar*sx, mFar*sy, -mFar );
glVertex3f ( mFar*sx, -mFar*sy, -mFar );
glVertex3f ( -mFar*sx, -mFar*sy, -mFar );
glEnd ();
// Subview Near plane
float l, r, t, b;
l = -sx + 2.0*sx*mTile.x; // Tile is in range 0 <= x,y <= 1
r = -sx + 2.0*sx*mTile.z;
t = sy - 2.0*sy*mTile.y;
b = sy - 2.0*sy*mTile.w;
glColor3f ( 0.8, 0.8, 0.0 );
glBegin ( GL_LINE_LOOP );
glVertex3f ( l * mNear, t * mNear, -mNear );
glVertex3f ( r * mNear, t * mNear, -mNear );
glVertex3f ( r * mNear, b * mNear, -mNear );
glVertex3f ( l * mNear, b * mNear, -mNear );
glEnd ();
// Subview Far plane
glBegin ( GL_LINE_LOOP );
glVertex3f ( l * mFar, t * mFar, -mFar );
glVertex3f ( r * mFar, t * mFar, -mFar );
glVertex3f ( r * mFar, b * mFar, -mFar );
glVertex3f ( l * mFar, b * mFar, -mFar );
glEnd ();
}
glPopMatrix ();
}
bool QFrustum::boundingBoxInFrustum(const QBoundingBox& boundingBox) const
{
QVector3D center = boundingBox.getCenter();
return boxInFrustum(center, boundingBox.max() - center);
}
