Added known issues test scenes

samples/basic/viewer/main.cc

@@ -625,6 +625,47 @@ void subtle_cases(pm::vertex_attribute<tg::pos3> const& pos)
     gv::view(pos, tg::scaling(2.0, 2.0, 2.0), "double transform");
 }
 
+void known_issues(pm::vertex_attribute<tg::pos3> const& pos)
+{
+    pm::Mesh mLine;
+    const auto v0 = mLine.vertices().add();
+    const auto v1 = mLine.vertices().add();
+    const auto _ = mLine.edges().add_or_get(v0, v1);
+    const auto line = mLine.vertices().make_attribute_from_data<tg::pos3>({{0, 0, 0}, {1, 0, 0}});
+    const auto lineColors = mLine.vertices().make_attribute_from_data<glow::colors::color>({{0.7f, 0.2f, 0.2f}, {0.2f, 0.7f, 0.2f}});
+
+    // Intersection of screen space camera facing lines and viewer grid creates artifacts
+    // Also the round caps of large screen space camera facing lines are not smoothly connecting to the straight line part
+    {
+        auto v = glow::viewer::view();
+        gv::view(gv::lines(line).camera_facing().line_width_px(500.0f), tg::color3::red, "ground shadow intersects red screen space camera facing line");
+        // It is fine for the green world space because the bounding box of world space moves the object up
+        gv::view(gv::lines(line).camera_facing().line_width_world(0.25f), tg::color3::green, tg::translation(0.0f, 0.0f, 1.0f));
+    }
+
+    // When setting a custom camera target view, the camera jumps the first time it is dragged with the left or right mouse button
+    {
+        gv::view(pos, gv::camera_transform(tg::pos3(1, 1, 1), tg::pos3(0, 0, 0)), "explicit start position and target creates jumping camera upon first drag");
+        // gv::camera_orientation works fine
+        gv::view(pos, gv::camera_orientation(125_deg, -15_deg, 1.7f), "explicit camera azimuth/altitude/distance works fine");
+    }
+
+    // Artifacts on grazing angles
+    // When the camera is outside of the capsule but close to the line spanned by its axis, all sorts of artifacts occur
+    {
+        gv::view(gv::lines(line).line_width_px(250.0f), lineColors, "artifacts on grazing angles (screen space)");
+        gv::view(gv::lines(line).line_width_world(1.5f), lineColors, tg::translation(0.f, 0.f, 5.f), "artifacts on grazing angles (screen space)");
+        // Screen space camera facing lines seem fine
+        // gv::view(gv::lines(line).line_width_px(250.0f).camera_facing(), lineColors, tg::translation(0.0f, 0.0f, -25.f));
+    }
+
+    // Camera facing points are always black
+    {
+        gv::view(gv::points(pos).square(), tg::color3::cyan, "camera facing points are black even though color configured");
+        // gv::no_shading makes no difference
+    }
+}
+
 int main()
 {
     // create a rendering context
@@ -671,5 +712,8 @@ int main()
         headless_screenshot(pos);
     }
 
+    // known issues
+    known_issues(pos);
+
     return EXIT_SUCCESS;
 }