Add unit tests and fix bugs for sprites

[matt439]

Description

There are currently no unit tests for sprites. A comprehensive set of tests have been added which cover most sprite methods, with the exception of those which rely on a window. In the process of creating the tests, I discovered multiple bugs which have been also been rectified.

Position and Velocity Type Changes

_sprite_data uses the point_2d and velocity_2d types for position and velocity respectively. point_2d and velocity_2d both use the double type. sprite_x, sprite_y, sprite_set_x, sprite_set_y, sprite_dx, sprite_dy, sprite_set_dx, and sprite_set_dy use the float type leading to unnecessary casting. Issues arise when the value stored in point_2d or vector_2d's double is outside the range of float. The methods have been altered to accept and return double.

Sprite-Point Collision Bug at Corners

sprite_point_collision calls sprite_collision_circle, which then calls bitmap_cell_circle which generates a circle which does not encompass the sprite. Points tested at the edges of the sprite will incorrectly return no collision. This occurs because the function uses the greater of a sprite's half-width or half-height as the radius. Instead, the length of the hypotenuse of a right triangle formed with the sprite's half-width and half-height as the opposite and adjacent should equal the circle's radius. bitmap_bounding_circle has also been corrected as it contains the same bug.

Point Methods Type Changes

point_in_circle casts double to long long which causes inaccuracy due to the rounding errors. The method has been altered to retain circle radius' double precision. In addition, point_in_circle calls point_point_distance which returns float instead of double. point_point_distance has been altered to return double, retaining the double precision.

Sprite Speed Methods Type Changes

sprite_speed and sprite_set_speed return and accept float, while calling the methods vector_magnitude, vector_multiply, and unit_vector which all operate at double precision. sprite_speed and sprite_set_speed have been altered to use double precision.

Sprite Rotation Periodicity

sprite_set_rotation incorrectly returns 360 when the input value equals 360. Instead, it should convert 360 to 0 degrees.

Additional Unit Tests

As the methods in sprite.cpp make calls to methods in images.cpp and point_geometry.cpp, it was necessary to add unit tests for those methods. In the case of images, there is an existing unit_test_bitmap.cpp file which I added to. For geometry tests, I created a new unit_test_geometry.cpp file. More geometry tests could be added in the future, however at this stage I only focused on those which are relevant to sprites.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as
  expected)

How Has This Been Tested?

Adding the new tests was achieved by running cmake -G "Unix Makefiles" . followed by make when in the /splashkit-core/projects/cmake directory.

Testing Checklist

• Tested with skunit_tests

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code