marenan

09-23-2006, 07:46 PM

Hi,

Now I can only create pleasing the positive stereo,but for negative, objects of the scene are not pop out of the screen,why?

the code:

StereoProjection (double dfLeftBorder, double dfRightBorder,

double dfBottomBorder, double dfTopBorder, double dfNearBorder,

double dfFarBorder, double dfTargetPlane, double dfCameraToTargetDistance,

double dfStereoMagnitudeAdj, double dfParallaxBalanceAdj,

int WhichEyeProjection)

// Perform the asymmetric frustum perspective projection for one eye's

// subfield.

// The projection is in the direction of the negative z axis.

//

// dfLeftBorder, dfRightBorder, dfBottomBorder, dfTopBorder =

// The coordinate range, in the z-axis target plane, which will be

// displayed on the screen. The ratio between (dfRightBorder-dfLeftBorder)

// and (dfTopBorder-dfBottomBorder) should equal the aspect ratio of the

// scene. Also, dfLeftBorder must be less than dfRightBorder, and

// dfTopBorder must be less than dfBottomBorder.

//

// dfNearBorder, dfFarBorder =

// The z-coordinate values of the clipping planes. Since the projection is

// in the direction of the negative z axis, dfNearBorder needs to be

// greater than dfFarBorder. Any element with a z-coordinate value greater

// than dfNearBorder, or less than dfFarBorder, will be clipped out.

//

// dfTargetPlane =

// The z-coordinate value of the mid-target plane that will, by default,

// project to zero parallax. This value should reside somewhere between

// dfNearBorder and dfFarBorder.

//

// dfCameraToTargetDistance =

// The distance from the center of projection to the plane of zero

// parallax. This distance needs to be greater than the difference between

// dfNearBorder and dfTargetPlane, in order for the near clipping plane

// to lie in front of the camera.

//

// dfStereoMagnitudeAdj =

// The desired magnitude of the stereo effect. 0.0 would result in no

// stereo effect at all, 1.0 would be a good default value, 2.0 would

// be a very strong (perhaps uncomfortable) stereo effect. This value

// should never be less than 0.0.

//

// dfParallaxBalanceAdj =

// The amount by which to affect the asymmetry of the projection frustum,

// effectively adjusting the stereo parallax balance. 0.0 would result

// in extreme negative parallax (with objects at infinite distance

// projecting to display surface), 1.0 would be a good default value

// (dfTargetPlane will project to zero parallax at the display surface),

// 2.0 would result in considerable positive parallax (most of the scene

// projecting behind the display surface). This value should never be less

// than 0.0. When this value equals 0.0, the projection frustum is

// perfectly symmetrical.

//

// WhichEyeProjection =

// Equals LEFT_EYE_PROJECTION or RIGHT_EYE_PROJECTION.

{

// the X & Y axis ranges, in the target Z plane

double dfXRange = dfRightBorder - dfLeftBorder;

double dfYRange = dfTopBorder - dfBottomBorder;

// midpoints of the X & Y axis ranges

double dfXMidpoint = (dfRightBorder + dfLeftBorder) / 2.0;

double dfYMidpoint = (dfTopBorder + dfBottomBorder) / 2.0;

// convert clipping plane positions to distances in front of camera

double dfCameraPlane = dfTargetPlane + dfCameraToTargetDistance;

double dfNearClipDistance = dfCameraPlane - dfNearBorder;

double dfFarClipDistance = dfCameraPlane - dfFarBorder;

// Determine the stereoscopic camera offset. A good rule of thumb is

// for the overall camera separation to equal about 7% of the

// window's X-axis range in the XY-plane of the target

// ("target" being mid-object or the center of interest in the

// scene).

double dfStereoCameraOffset = dfXRange * STEREO_MAGNITUDE_CONSTANT *

dfStereoMagnitudeAdj;

dfStereoCameraOffset /= 2.0; // offset each camera by half the overall sep

if (WhichEyeProjection == LEFT_EYE_PROJECTION) // left cam has neg offset

dfStereoCameraOffset = -dfStereoCameraOffset;

// Determine the amount by which the projection frustum will be made

// asymmetrical in order to affect a nice parallax balance between

// negative parallax (popping out of the display) and positive

// parallax (residing behind the display surface). With no frustum

// asymmetry, everything resides in negative parallax.

double dfFrustumAsymmetry = -dfStereoCameraOffset * dfParallaxBalanceAdj;

// since glFrustum() maps the window borders based on the near clipping

// plane rather than the target plane, X and Y range values need

// to be adjusted by the ratio of those two distances

double n_over_d = dfNearClipDistance / dfCameraToTargetDistance;

dfXRange *= n_over_d;

dfYRange *= n_over_d;

dfFrustumAsymmetry *= n_over_d;

// determine the shape of the projection frustum; note that if

// FrustumRight doesn't equal -FrustumLeft, that makes this an

// asymmetric frustum projection

double FrustumTop = dfYRange / 2.0;

double FrustumBottom = -dfYRange / 2.0;

double FrustumRight = (dfXRange / 2.0) + dfFrustumAsymmetry;

double FrustumLeft = (-dfXRange / 2.0) + dfFrustumAsymmetry;

// glMatrixMode(GL_PROJECTION) needs to have been called already

glLoadIdentity(); // obtain a vanilla trans matrix to modify

// this matrix transformation performs the actual persp projection

glFrustum (FrustumLeft, FrustumRight, FrustumBottom, FrustumTop,

dfNearClipDistance, dfFarClipDistance);

// this matrix transformation does two things: Translates the stereo

// camera towards the left (left camera) or the right (right

// camera), and also offsets the entire geometry such that the

// virtual camera is at (0.0, 0.0, 0.0) where glFrustum() expects

// it to be

glTranslated (-dfXMidpoint - dfStereoCameraOffset, -dfYMidpoint,

-dfCameraPlane);

}

Now I can only create pleasing the positive stereo,but for negative, objects of the scene are not pop out of the screen,why?

the code:

StereoProjection (double dfLeftBorder, double dfRightBorder,

double dfBottomBorder, double dfTopBorder, double dfNearBorder,

double dfFarBorder, double dfTargetPlane, double dfCameraToTargetDistance,

double dfStereoMagnitudeAdj, double dfParallaxBalanceAdj,

int WhichEyeProjection)

// Perform the asymmetric frustum perspective projection for one eye's

// subfield.

// The projection is in the direction of the negative z axis.

//

// dfLeftBorder, dfRightBorder, dfBottomBorder, dfTopBorder =

// The coordinate range, in the z-axis target plane, which will be

// displayed on the screen. The ratio between (dfRightBorder-dfLeftBorder)

// and (dfTopBorder-dfBottomBorder) should equal the aspect ratio of the

// scene. Also, dfLeftBorder must be less than dfRightBorder, and

// dfTopBorder must be less than dfBottomBorder.

//

// dfNearBorder, dfFarBorder =

// The z-coordinate values of the clipping planes. Since the projection is

// in the direction of the negative z axis, dfNearBorder needs to be

// greater than dfFarBorder. Any element with a z-coordinate value greater

// than dfNearBorder, or less than dfFarBorder, will be clipped out.

//

// dfTargetPlane =

// The z-coordinate value of the mid-target plane that will, by default,

// project to zero parallax. This value should reside somewhere between

// dfNearBorder and dfFarBorder.

//

// dfCameraToTargetDistance =

// The distance from the center of projection to the plane of zero

// parallax. This distance needs to be greater than the difference between

// dfNearBorder and dfTargetPlane, in order for the near clipping plane

// to lie in front of the camera.

//

// dfStereoMagnitudeAdj =

// The desired magnitude of the stereo effect. 0.0 would result in no

// stereo effect at all, 1.0 would be a good default value, 2.0 would

// be a very strong (perhaps uncomfortable) stereo effect. This value

// should never be less than 0.0.

//

// dfParallaxBalanceAdj =

// The amount by which to affect the asymmetry of the projection frustum,

// effectively adjusting the stereo parallax balance. 0.0 would result

// in extreme negative parallax (with objects at infinite distance

// projecting to display surface), 1.0 would be a good default value

// (dfTargetPlane will project to zero parallax at the display surface),

// 2.0 would result in considerable positive parallax (most of the scene

// projecting behind the display surface). This value should never be less

// than 0.0. When this value equals 0.0, the projection frustum is

// perfectly symmetrical.

//

// WhichEyeProjection =

// Equals LEFT_EYE_PROJECTION or RIGHT_EYE_PROJECTION.

{

// the X & Y axis ranges, in the target Z plane

double dfXRange = dfRightBorder - dfLeftBorder;

double dfYRange = dfTopBorder - dfBottomBorder;

// midpoints of the X & Y axis ranges

double dfXMidpoint = (dfRightBorder + dfLeftBorder) / 2.0;

double dfYMidpoint = (dfTopBorder + dfBottomBorder) / 2.0;

// convert clipping plane positions to distances in front of camera

double dfCameraPlane = dfTargetPlane + dfCameraToTargetDistance;

double dfNearClipDistance = dfCameraPlane - dfNearBorder;

double dfFarClipDistance = dfCameraPlane - dfFarBorder;

// Determine the stereoscopic camera offset. A good rule of thumb is

// for the overall camera separation to equal about 7% of the

// window's X-axis range in the XY-plane of the target

// ("target" being mid-object or the center of interest in the

// scene).

double dfStereoCameraOffset = dfXRange * STEREO_MAGNITUDE_CONSTANT *

dfStereoMagnitudeAdj;

dfStereoCameraOffset /= 2.0; // offset each camera by half the overall sep

if (WhichEyeProjection == LEFT_EYE_PROJECTION) // left cam has neg offset

dfStereoCameraOffset = -dfStereoCameraOffset;

// Determine the amount by which the projection frustum will be made

// asymmetrical in order to affect a nice parallax balance between

// negative parallax (popping out of the display) and positive

// parallax (residing behind the display surface). With no frustum

// asymmetry, everything resides in negative parallax.

double dfFrustumAsymmetry = -dfStereoCameraOffset * dfParallaxBalanceAdj;

// since glFrustum() maps the window borders based on the near clipping

// plane rather than the target plane, X and Y range values need

// to be adjusted by the ratio of those two distances

double n_over_d = dfNearClipDistance / dfCameraToTargetDistance;

dfXRange *= n_over_d;

dfYRange *= n_over_d;

dfFrustumAsymmetry *= n_over_d;

// determine the shape of the projection frustum; note that if

// FrustumRight doesn't equal -FrustumLeft, that makes this an

// asymmetric frustum projection

double FrustumTop = dfYRange / 2.0;

double FrustumBottom = -dfYRange / 2.0;

double FrustumRight = (dfXRange / 2.0) + dfFrustumAsymmetry;

double FrustumLeft = (-dfXRange / 2.0) + dfFrustumAsymmetry;

// glMatrixMode(GL_PROJECTION) needs to have been called already

glLoadIdentity(); // obtain a vanilla trans matrix to modify

// this matrix transformation performs the actual persp projection

glFrustum (FrustumLeft, FrustumRight, FrustumBottom, FrustumTop,

dfNearClipDistance, dfFarClipDistance);

// this matrix transformation does two things: Translates the stereo

// camera towards the left (left camera) or the right (right

// camera), and also offsets the entire geometry such that the

// virtual camera is at (0.0, 0.0, 0.0) where glFrustum() expects

// it to be

glTranslated (-dfXMidpoint - dfStereoCameraOffset, -dfYMidpoint,

-dfCameraPlane);

}