LibGfx: Implement even-odd method for Quad::contains() and add tests

[a4v2d4]

First PR :)

LibGfx: Addressed simple FIXME comment to improve implementation of LibGfx::Quad::contains():

• Now uses even-odd method to determine if point is inside/outside
• Added TestQuad.cpp for basic verification of current functions

Docs: Added homebrew package shellcheck to build instructions documentation because I needed that to build on macOS

[DanShaders]

This has inconsistent behavior at edges (not like code you're replacing had it but), i. e. the following test passes:

TEST_CASE(foo)
{
    Gfx::Point<int> p1 { 0, 0 };
    Gfx::Point<int> p2 { 2, 0 };
    Gfx::Point<int> p3 { 2, 2 };
    Gfx::Point<int> p4 { 0, 2 };
    Gfx::Quad<int> quad { p1, p2, p3, p4 };

    EXPECT(quad.contains({ 0, 0 }));
    EXPECT(quad.contains({ 1, 0 }));
    EXPECT(quad.contains({ 0, 1 }));

    EXPECT(!quad.contains({ 2, 0 }));
    EXPECT(!quad.contains({ 2, 1 }));
    EXPECT(!quad.contains({ 2, 2 }));
    EXPECT(!quad.contains({ 1, 2 }));
    EXPECT(!quad.contains({ 0, 2 }));
}

[a4v2d4]

@DanShaders I appreciate your review, ty.

Turns out this behavior is consistent with LibGfx::Rect, i.e. the following test case also passes:

TEST_CASE(foo)
{
    Gfx::Point<int> p1 { 0, 0 };
    Gfx::Point<int> p2 { 2, 0 };
    Gfx::Point<int> p3 { 2, 2 };
    Gfx::Point<int> p4 { 0, 2 };
    Gfx::Quad<int> quad { p1, p2, p3, p4 };

    EXPECT(quad.contains({ 0, 0 }));
    EXPECT(quad.contains({ 1, 0 }));
    EXPECT(quad.contains({ 0, 1 }));

    EXPECT(!quad.contains({ 2, 0 }));
    EXPECT(!quad.contains({ 2, 1 }));
    EXPECT(!quad.contains({ 2, 2 }));
    EXPECT(!quad.contains({ 1, 2 }));
    EXPECT(!quad.contains({ 0, 2 }));

    Gfx::Rect<int> bounding_rect = quad.bounding_rect();
    EXPECT(bounding_rect.contains({ 0, 0 }));
    EXPECT(bounding_rect.contains({ 1, 0 }));
    EXPECT(bounding_rect.contains({ 0, 1 }));

    EXPECT(!bounding_rect.contains({ 2, 0 }));
    EXPECT(!bounding_rect.contains({ 2, 1 }));
    EXPECT(!bounding_rect.contains({ 2, 2 }));
    EXPECT(!bounding_rect.contains({ 1, 2 }));
    EXPECT(!bounding_rect.contains({ 0, 2 }));
}

Looks like LibGfx::Rect::contains() treats points at x() and y() inclusively and x() + width() and y() + height() exclusively.

Just added new test case to verify Quad and Rect contains() implementations are consistent.

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[github-actions[bot]]

This pull request has been closed because it has not had recent activity. Feel free to re-open if you wish to still contribute these changes. Thank you for your contributions!