OpenCascade/occt
1
0
Fork 0
mirror of https://git.dev.opencascade.org/repos/occt.git synced 2025-04-04 18:06:22 +03:00
Code Packages Releases Activity

0026401: Visualization - small boxes in front of big one disappear in perspective view

Browse Source
This commit is contained in:
apl 2015-07-20 20:26:05 +03:00 committed by bugmaster
parent 29a4908e18
commit 5a19c30371
2 changed files with 117 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
src/Graphic3d/Graphic3d_Camera.cxx
View File

@ -1040,7 +1040,9 @@ void Graphic3d_Camera::ZFitAll (const Standard_Real theScaleFactor, const Bnd_Bo
aPntsToMeasure.Append (gp_Pnt (aGraphicBB[3], aGraphicBB[4], aGraphicBB[2]));
aPntsToMeasure.Append (gp_Pnt (aGraphicBB[3], aGraphicBB[4], aGraphicBB[5]));
if (!theMinMax.IsVoid() && !theMinMax.IsWhole())
Standard_Boolean isFiniteMinMax = !theMinMax.IsVoid() && !theMinMax.IsWhole();
if (isFiniteMinMax)
{
Standard_Real aMinMax[6];
theMinMax.Get (aMinMax[0], aMinMax[1], aMinMax[2], aMinMax[3], aMinMax[4], aMinMax[5]);
@ -1060,10 +1062,10 @@ void Graphic3d_Camera::ZFitAll (const Standard_Real theScaleFactor, const Bnd_Bo
gp_Pnt aCamEye = myEye;
gp_Pln aCamPln (aCamEye, aCamDir);
Standard_Real aModelMinDist = RealLast();
Standard_Real aModelMaxDist = RealFirst();
Standard_Real aGraphicMinDist = RealLast();
Standard_Real aGraphicMaxDist = RealFirst();
Standard_Real aModelMinDist = RealLast();
Standard_Real aModelMaxDist = RealFirst();
Standard_Real aGraphMinDist = RealLast();
Standard_Real aGraphMaxDist = RealFirst();
const gp_XYZ& anAxialScale = myAxialScale;
@ -1087,16 +1089,16 @@ void Graphic3d_Camera::ZFitAll (const Standard_Real theScaleFactor, const Bnd_Bo
}
// The first eight points are from theGraphicBB, the last eight points are from theMinMax (can be absent).
Standard_Real& aChangeMinDist = aCounter >= 8 ? aModelMinDist : aGraphicMinDist;
Standard_Real& aChangeMaxDist = aCounter >= 8 ? aModelMaxDist : aGraphicMaxDist;
Standard_Real& aChangeMinDist = aCounter >= 8 ? aModelMinDist : aGraphMinDist;
Standard_Real& aChangeMaxDist = aCounter >= 8 ? aModelMaxDist : aGraphMaxDist;
aChangeMinDist = Min (aDistance, aChangeMinDist);
aChangeMaxDist = Max (aDistance, aChangeMaxDist);
aCounter++;
}
// Compute depth of bounding box center.
Standard_Real aMidDepth = (aGraphicMinDist + aGraphicMaxDist) * 0.5;
Standard_Real aHalfDepth = (aGraphicMaxDist - aGraphicMinDist) * 0.5;
Standard_Real aMidDepth = (aGraphMinDist + aGraphMaxDist) * 0.5;
Standard_Real aHalfDepth = (aGraphMaxDist - aGraphMinDist) * 0.5;
// Compute enlarged or shrank near and far z ranges.
Standard_Real aZNear = aMidDepth - aHalfDepth * theScaleFactor;
@ -1110,27 +1112,6 @@ void Graphic3d_Camera::ZFitAll (const Standard_Real theScaleFactor, const Bnd_Bo
SetZRange (DEFAULT_ZNEAR, DEFAULT_ZFAR);
return;
}
// For better perspective the zNear value should not be less than zEpsilon (zFar).
// If zNear computed by graphical boundaries do not meet the rule (e.g. it is negative
// when computing it for grid) it could be increased up to minimum depth computed by
// application min max values. This means that z-fit can sacrifice presentation of
// non primary application graphical objects in favor of better perspective projection;
if (aZNear < zEpsilon (aZFar))
{
// Otherwise it should be increased up to zEpsilon (1.0) to avoid clipping of primary
// graphical objects.
if (aModelMinDist < zEpsilon (aZFar))
{
aMidDepth = (aModelMinDist + aModelMaxDist) * 0.5;
aHalfDepth = (aModelMinDist - aModelMaxDist) * 0.5;
aZNear = Max (zEpsilon(), aMidDepth - aHalfDepth * theScaleFactor);
}
else
{
aZNear = zEpsilon (aZFar);
}
}
}
//
@ -1164,9 +1145,43 @@ void Graphic3d_Camera::ZFitAll (const Standard_Real theScaleFactor, const Bnd_Bo
if (!IsOrthographic())
{
// Compensate zNear, zFar conversion errors for perspective projection.
aZNear -= aZFar * zEpsilon (aZNear) / (aZFar - zEpsilon (aZNear));
aZFar += zEpsilon (aZFar);
// For perspective projection, the value of z in normalized device coordinates is non-linear
// function of eye z coordinate. For fixed-point depth representation resolution of z in
// model-view space will grow towards zFar plane and its scale depends mostly on how far is zNear
// against camera's eye. The purpose of the code below is to select most appropriate zNear distance
// to balance between clipping (less zNear, more chances to observe closely small models without clipping)
// and resolution of depth. A well applicable criteria to this is a ratio between resolution of z at center
// of model boundaries and the distance to that center point. The ratio is chosen empirically and validated
// by tests database. It is considered to be ~0.001 (0.1%) for 24 bit depth buffer, for less depth bitness
// the zNear will be placed similarly giving lower resolution.
// Approximation of the formula for respectively large z range is:
// zNear = [z * (1 + k) / (k * c)],
// where:
// z - distance to center of model boundaries;
// k - chosen ratio, c - capacity of depth buffer;
// k = 0.001, k * c = 1677.216, (1 + k) / (k * c) ~ 5.97E-4
//
// The function uses center of model boundaries computed from "theMinMax" boundaries (instead of using real
// graphical boundaries of all displayed objects). That means that it can sacrifice resolution of presentation
// of non primary ("infinite") application graphical objects in favor of better perspective projection of the
// small applicative objects measured with "theMinMax" values.
Standard_Real aZRange = isFiniteMinMax ? aModelMaxDist - aModelMinDist : aGraphMaxDist - aGraphMinDist;
Standard_Real aZMin = isFiniteMinMax ? aModelMinDist : aGraphMinDist;
Standard_Real aZ = aZMin < 0 ? aZRange / 2.0 : aZRange / 2.0 + aZMin;
Standard_Real aZNearMin = aZ * 5.97E-4;
if (aZNear < aZNearMin)
{
// Clip zNear according to the minimum value matching the quality.
aZNear = aZNearMin;
}
else
{
// Compensate zNear conversion errors for perspective projection.
aZNear -= aZFar * zEpsilon (aZNear) / (aZFar - zEpsilon (aZNear));
}
// Compensate zFar conversion errors for perspective projection.
aZFar += zEpsilon (aZFar);
// Ensure that after all the zNear is not a negative value.
if (aZNear < zEpsilon())

69
tests/bugs/vis/bug26401 Normal file
View File

@ -0,0 +1,69 @@
puts "========"
puts "OCC26401"
puts "========"
puts ""
###########################################################################################
# Visualization - small boxes in front of big one disappear in perspective view
###########################################################################################
# Boxes {1 x 1 x 1}
box b0 0 0 0 1 1 1
box b1 -1 0 0 1 1 1
box b2 1 0 0 1 1 1
box b3 0 1 0 1 1 1
box b4 -1 1 0 1 1 1
box b5 1 1 0 1 1 1
vinit View1
vclear
vaxo
vsetdispmode 1
vcamera -persp
vdisplay b0 b1 b2 b3 b4 b5
vsetcolor b1 b2 GREEN
vsetcolor b4 b5 RED
vsetcolor b3 GRAY55
vfit
vautozfit
vzrange
vtrihedron t
set color "[vreadpixel 230 230 rgb]"
if { [lindex $color 0] == 0 &&
[lindex $color 1] == 0 &&
[lindex $color 2] == 0 } {
puts "Error : Boxes disappear."
}
vdump $imagedir/${casename}_1.png
# Boxes {0.01 x 0.01 x 0.01}
box b0 0.00 0.00 0.00 0.01 0.01 0.01
box b1 -0.01 0.00 0.00 0.01 0.01 0.01
box b2 0.01 0.00 0.00 0.01 0.01 0.01
box b3 0.00 0.01 0.00 0.01 0.01 0.01
box b4 -0.01 0.01 0.00 0.01 0.01 0.01
box b5 0.01 0.01 0.00 0.01 0.01 0.01
vinit View2
vclear
vaxo
vsetdispmode 1
vcamera -persp
vdisplay b0 b1 b2 b3 b4 b5
vsetcolor b1 b2 GREEN
vsetcolor b4 b5 RED
vsetcolor b3 GRAY55
vfit
vautozfit
vzrange
vtrihedron t
set color "[vreadpixel 230 230 rgb]"
if { [lindex $color 0] == 0 &&
[lindex $color 1] == 0 &&
[lindex $color 2] == 0 } {
puts "Error : Boxes disappear."
}
vdump $imagedir/${casename}_2.png