From 2e04d2c1373d2fe45de2d0b96f91afca94f03dea Mon Sep 17 00:00:00 2001 From: Daniel van Vugt Date: Thu, 18 Jul 2019 16:56:41 +0800 Subject: [PATCH] clutter/point: Add ClutterPoint quarilateral testing API Add a function to check whether a point is inside a quadrilateral by checking the cross product of vectors with the quadrilateral points, and the point being checked. If the passed quadrilateral is zero-sized, no point is ever reported to be inside it. This will be used by the next commit when comparing the transformed actor vertices. https://gitlab.gnome.org/GNOME/mutter/merge_requests/189 --- clutter/clutter/clutter-base-types.c | 62 ++++++++++++++++++++ clutter/clutter/clutter-types.h | 3 + src/tests/clutter/conform/meson.build | 1 + src/tests/clutter/conform/point.c | 84 +++++++++++++++++++++++++++ 4 files changed, 150 insertions(+) create mode 100644 src/tests/clutter/conform/point.c diff --git a/clutter/clutter/clutter-base-types.c b/clutter/clutter/clutter-base-types.c index aeb25c90e..c84f9aa64 100644 --- a/clutter/clutter/clutter-base-types.c +++ b/clutter/clutter/clutter-base-types.c @@ -570,6 +570,68 @@ G_DEFINE_BOXED_TYPE_WITH_CODE (ClutterPoint, clutter_point, clutter_point_free, CLUTTER_REGISTER_INTERVAL_PROGRESS (clutter_point_progress)) +static int +clutter_point_compare_line (const ClutterPoint *p, + const ClutterPoint *a, + const ClutterPoint *b) +{ + float x1 = b->x - a->x; + float y1 = b->y - a->y; + float x2 = p->x - a->x; + float y2 = p->y - a->y; + float cross_z = x1 * y2 - y1 * x2; + + if (cross_z > 0.f) + return 1; + else if (cross_z < 0.f) + return -1; + else + return 0; +} + +/** + * clutter_point_inside_quadrilateral: + * @point: a #ClutterPoint to test + * @vertices: array of vertices of the quadrilateral, in clockwise order, + * from top-left to bottom-left + * + * Determines whether a point is inside the convex quadrilateral provided, + * and not on any of its edges or vertices. + * + * Returns: %TRUE if @point is inside the quadrilateral + */ +gboolean +clutter_point_inside_quadrilateral (const ClutterPoint *point, + const ClutterPoint *vertices) +{ + unsigned int i; + int first_side; + + first_side = 0; + + for (i = 0; i < 4; i++) + { + int side; + + side = clutter_point_compare_line (point, + &vertices[i], + &vertices[(i + 1) % 4]); + + if (side) + { + if (first_side == 0) + first_side = side; + else if (side != first_side) + return FALSE; + } + } + + if (first_side == 0) + return FALSE; + + return TRUE; +} + /* diff --git a/clutter/clutter/clutter-types.h b/clutter/clutter/clutter-types.h index 0f0fb1c2a..050802827 100644 --- a/clutter/clutter/clutter-types.h +++ b/clutter/clutter/clutter-types.h @@ -200,6 +200,9 @@ float clutter_point_distance (const ClutterPoint *a, const ClutterPoint *b, float *x_distance, float *y_distance); +CLUTTER_EXPORT +gboolean clutter_point_inside_quadrilateral (const ClutterPoint *point, + const ClutterPoint *vertices); /** * ClutterSize: diff --git a/src/tests/clutter/conform/meson.build b/src/tests/clutter/conform/meson.build index 6821e8963..cf91b374d 100644 --- a/src/tests/clutter/conform/meson.build +++ b/src/tests/clutter/conform/meson.build @@ -33,6 +33,7 @@ clutter_conform_tests_general_tests = [ 'interval', 'script-parser', 'units', + 'point', ] clutter_conform_tests_deprecated_tests = [ diff --git a/src/tests/clutter/conform/point.c b/src/tests/clutter/conform/point.c new file mode 100644 index 000000000..c8ecac709 --- /dev/null +++ b/src/tests/clutter/conform/point.c @@ -0,0 +1,84 @@ +#include "tests/clutter-test-utils.h" + +#include + +static void +point_on_nonempty_quadrilateral (void) +{ + int p; + static const ClutterPoint vertices[4] = + { + { 1.f, 2.f }, + { 6.f, 3.f }, + { 7.f, 6.f }, + { 0.f, 5.f } + }; + static const ClutterPoint points_inside[] = + { + { 2.f, 3.f }, + { 1.f, 4.f }, + { 5.f, 5.f }, + { 4.f, 3.f }, + }; + static const ClutterPoint points_outside[] = + { + { 3.f, 1.f }, + { 7.f, 4.f }, + { 4.f, 6.f }, + { 99.f, -77.f }, + { -1.f, 3.f }, + { -8.f, -8.f }, + { 11.f, 4.f }, + { -7.f, 4.f }, + }; + + for (p = 0; p < G_N_ELEMENTS (points_inside); p++) + { + const ClutterPoint *point = &points_inside[p]; + + g_assert_true (clutter_point_inside_quadrilateral (point, vertices)); + } + + for (p = 0; p < G_N_ELEMENTS (points_outside); p++) + { + const ClutterPoint *point = &points_outside[p]; + + g_assert_false (clutter_point_inside_quadrilateral (point, vertices)); + } +} + +static void +point_on_empty_quadrilateral (void) +{ + int p; + static const ClutterPoint vertices[4] = + { + { 5.f, 6.f }, + { 5.f, 6.f }, + { 5.f, 6.f }, + { 5.f, 6.f }, + }; + static const ClutterPoint points_outside[] = + { + { 3.f, 1.f }, + { 7.f, 4.f }, + { 4.f, 6.f }, + { 99.f, -77.f }, + { -1.f, 3.f }, + { -8.f, -8.f }, + }; + + for (p = 0; p < G_N_ELEMENTS (points_outside); p++) + { + const ClutterPoint *point = &points_outside[p]; + + g_assert_false (clutter_point_inside_quadrilateral (point, vertices)); + } + + g_assert_false (clutter_point_inside_quadrilateral (&vertices[0], vertices)); +} + +CLUTTER_TEST_SUITE ( + CLUTTER_TEST_UNIT ("/point/on_nonempty_quadrilateral", point_on_nonempty_quadrilateral) + CLUTTER_TEST_UNIT ("/point/on_empty_quadrilateral", point_on_empty_quadrilateral) +)