Fix QTBUG-18823.

Implemented correctly the clip space algorithm and
fixed a number of minor but fatal problems with the
previous implementation.

Also added useful debug to the camera class, which
helped during debugging.

Made a correction to the frustum doc, which impacted
the testing work, and added a section on the aspect
ratio which had garnered some questions on the list.

In the tests, added some tests that cover the view
frustum being forwards or backwards over the object
being viewed/culled, which was not covered before.

Change-Id: I488441eb89b5b112daa973d13260880ee3286038
Reviewed-on: http://codereview.qt.nokia.com/2258
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Danny Pope <daniel.pope@nokia.com>
Reviewed-by: Zheng Liu <zheng.g.liu@nokia.com>
Reviewed-by: Sarah Jane Smith <sarah.j.smith@nokia.com>

1 files changed, 73 insertions, 22 deletions

diff --git a/tests/auto/threed/qglpainter/tst_qglpainter.cpp b/tests/auto/threed/qglpainter/tst_qglpainter.cpp
index 38de2ff78..5fb862765 100644
--- a/tests/auto/threed/qglpainter/tst_qglpainter.cpp
+++ b/tests/auto/threed/qglpainter/tst_qglpainter.cpp
@@ -609,7 +609,7 @@ void tst_QGLPainter::basicCullable()
     QVERIFY(painter.isCullable(box8));
 }
 
-static void setupTestCamera(QGLCamera &camera)
+static void setupTestCamera(QGLCamera &camera, float distance)
 {
     // These values are based on the special camera as per the images in
     // doc/src/images/view-frustum*
@@ -621,19 +621,25 @@ static void setupTestCamera(QGLCamera &camera)
     camera.setNearPlane(2.2f);
     camera.setFarPlane(14.0f);
 
-    // This value comes from the ratio of the far plane size 4 x 4 to the
+    // This value comes from the ratio of the far plane size 8 x 8 to the
     // far plane distance, multiplied by the near plane, to give the near
-    // plane size:  2.2 x (4 / 14) = 0.62857
-    camera.setViewSize(QSizeF(0.62857f, 0.62857f));
+    // plane size:  2.2 x (4 / 14) = 1.257
+    camera.setViewSize(QSizeF(1.257f, 1.257f));
 
     // as shown in the images, we use a camera at -z instead of the default +z
     // but the center remains the same at 0, 0, 0
-    camera.setEye(QVector3D(0, 0, -8.0f));
+    camera.setEye(QVector3D(0, 0, distance));
+
+    // if the distance would push the camera eye past the view center
+    // move the view center away
+    if (distance > 0.0f)
+        camera.setCenter(QVector3D(0.0f, 0.0f, distance + 2));
 }
 
 void tst_QGLPainter::isCullable_data()
 {
     QTest::addColumn<float>("angle");
+    QTest::addColumn<float>("distance");
     QTest::addColumn<bool>("culled");
     QTest::addColumn<bool>("center_culled");
 
@@ -641,15 +647,28 @@ void tst_QGLPainter::isCullable_data()
     // It should be visible between -20 and 20 degrees but otherwise not.
     // Also check the point at the center of the box.
 
-    QTest::newRow("culled-neg40") << -40.0f << true << true;
-    QTest::newRow("culled-neg30") << -30.0f << true << true;
-    QTest::newRow("part-vis-neg20") << -20.0f << false << true;
-    QTest::newRow("part-vis-neg10") << -10.0f << false << false;
-    QTest::newRow("all-vis-00") << 0.0f << false << false;
-    QTest::newRow("part-vis-pos10") << 10.0f << false << false;
-    QTest::newRow("part-vis-pos20") << 20.0f << false << true;
-    QTest::newRow("culled-pos30") << 30.0f << true << true;
-    QTest::newRow("culled-pos40") << 40.0f << true << true;
+    QTest::newRow("culled-neg40") << -40.0f << -8.0f << true << true;
+    QTest::newRow("culled-neg30") << -30.0f << -8.0f << true << true;
+    QTest::newRow("part-vis-neg20") << -20.0f << -8.0f << false << false;
+    QTest::newRow("part-vis-neg10") << -10.0f << -8.0f << false << false;
+    QTest::newRow("all-vis-00") << 0.0f << -8.0f << false << false;
+    QTest::newRow("part-vis-pos10") << 10.0f << -8.0f << false << false;
+    QTest::newRow("part-vis-pos20") << 20.0f << -8.0f << false << false;
+    QTest::newRow("culled-pos30") << 30.0f << -8.0f << true << true;
+    QTest::newRow("culled-pos40") << 40.0f << -8.0f << true << true;
+
+    // Check when the eye is at varying distances from the box, with
+    // (in one case with an angle for good measure) so that it needs
+    // testing against the near and far planes.
+
+    QTest::newRow("culled-eye-z+2") << 0.0f << 2.0f << true << true;
+    QTest::newRow("culled-eye-z+0") << 0.0f << 0.0f << true << true;
+    QTest::newRow("part-vis-eye-z-2-around-np") << 0.0f << -2.0f << false << true;
+    QTest::newRow("part-vis-eye-z-3-around-np") << 0.0f << -3.0f << false << false;
+    QTest::newRow("part-vis-eye-z-4-close-np") << 0.0f << -4.0f << false << false;
+    QTest::newRow("part-vis-eye-z-14.5") << 0.0f << -14.5f << false << true;
+    QTest::newRow("part-vis-eye-z-14-angle-20") << 20.0f << -14.0f << false << false;
+    QTest::newRow("culled-eye-z-20") << 0.0f << -20.0f << true << true;
 }
 
 void tst_QGLPainter::isCullable()
@@ -659,13 +678,16 @@ void tst_QGLPainter::isCullable()
     painter.modelViewMatrix().setToIdentity();
 
     QGLCamera camera;
-    setupTestCamera(camera);
 
     QFETCH(float, angle);
+    QFETCH(float, distance);
     QFETCH(bool, culled);
     QFETCH(bool, center_culled);
 
-    camera.rotateEye(camera.pan(angle));
+    setupTestCamera(camera, distance);
+    if (angle != 0.0f)
+        camera.rotateEye(camera.pan(angle));
+
     painter.setCamera(&camera);
 
     QBox3D box(QVector3D(-1, -1, -1), QVector3D(1, 1, 1));
@@ -675,28 +697,57 @@ void tst_QGLPainter::isCullable()
 
 void tst_QGLPainter::isCullableVert_data()
 {
-    isCullable_data();
+    QTest::addColumn<float>("angle");
+    QTest::addColumn<float>("distance");
+    QTest::addColumn<bool>("culled");
+    QTest::addColumn<bool>("center_culled");
+
+    // Check the cullability of a box at 10 degree increments of rotation.
+    // It should be visible between -20 and 20 degrees but otherwise not.
+    // Also check the point at the center of the box.
+
+    QTest::newRow("culled-neg40") << -40.0f << -8.0f << true << true;
+    QTest::newRow("culled-neg30") << -30.0f << -8.0f << true << true;
+    QTest::newRow("part-vis-neg20") << -20.0f << -8.0f << false << true;
+    QTest::newRow("part-vis-neg10") << -10.0f << -8.0f << false << false;
+    QTest::newRow("all-vis-00") << 0.0f << -8.0f << false << false;
+    QTest::newRow("part-vis-pos10") << 10.0f << -8.0f << false << false;
+    QTest::newRow("part-vis-pos20") << 20.0f << -8.0f << false << true;
+    QTest::newRow("culled-pos30") << 30.0f << -8.0f << true << true;
+    QTest::newRow("culled-pos40") << 40.0f << -8.0f << true << true;
+
+    QTest::newRow("culled-eye-z+2") << 0.0f << 2.0f << true << true;
+    QTest::newRow("culled-eye-z+0") << 0.0f << 0.0f << true << true;
+    QTest::newRow("part-vis-eye-z-2-around-np") << 0.0f << -2.0f << false << true;
+    QTest::newRow("part-vis-eye-z-3-around-np") << 0.0f << -3.0f << false << false;
+    QTest::newRow("part-vis-eye-z-4-close-np") << 0.0f << -4.0f << false << false;
+    QTest::newRow("part-vis-eye-z-14.2") << 0.0f << -14.2f << false << true;
+    QTest::newRow("part-vis-eye-z-14-angle-20") << 20.0f << -14.0f << false << true;
+    QTest::newRow("culled-eye-z-20") << 0.0f << -20.0f << true << true;
 }
 
 void tst_QGLPainter::isCullableVert()
 {
-    QSKIP("isCullableVert not passing currently", SkipAll);
+    //QSKIP("isCullableVert not passing currently", SkipAll);
     // same test as isCullable, except we tilt the camera forward
     // and back instead of rotating it from side to side
-    // since the view frustum, and the box are square in section
-    // they must produce the same results
+    // since the view frustum is typically not square in section
+    // as it depends on the surface, this will give different results.
     QGLWidget w;
     QGLPainter painter(&w);
     painter.modelViewMatrix().setToIdentity();
 
     QGLCamera camera;
-    setupTestCamera(camera);
 
     QFETCH(float, angle);
+    QFETCH(float, distance);
     QFETCH(bool, culled);
     QFETCH(bool, center_culled);
 
-    camera.rotateEye(camera.tilt(angle));
+    setupTestCamera(camera, distance);
+    if (angle != 0.0f)
+        camera.rotateEye(camera.tilt(angle));
+
     painter.setCamera(&camera);
 
     QBox3D box(QVector3D(-1, -1, -1), QVector3D(1, 1, 1));