vec2.h File Reference

Provides 2D vector functionality for positions, directions, and transformations. More...

#include <SDL.h>
#include <stdbool.h>

Go to the source code of this file.

Classes
struct	Vec2
	A 2D vector structure. More...

Typedefs
typedef struct Vec2	Vec2

Functions
float	Vec2_Magnitude (Vec2 v)
	Calculate the magnitude (length) of a vector.
float	Vec2_Distance (Vec2 a, Vec2 b)
	Calculate the distance between two vectors.
Vec2	Vec2_Normalize (Vec2 v)
	Normalize a vector (make it unit length)
Vec2	Vec2_Add (Vec2 a, Vec2 b)
	Add two vectors.
Vec2	Vec2_Increment (Vec2 *a, Vec2 b)
	Increment vector a by vector b.
Vec2	Vec2_Subtract (Vec2 a, Vec2 b)
	Subtract vector b from vector a.
Vec2	Vec2_Decrement (Vec2 *a, Vec2 b)
	Decrement vector a by vector b.
Vec2	Vec2_Multiply (Vec2 v, float scalar)
	Multiply a vector by a scalar.
Vec2	Vec2_Divide (Vec2 v, float scalar)
	Divide a vector by a scalar.
float	Vec2_Dot (Vec2 a, Vec2 b)
	Calculate the dot product of two vectors.
Vec2	Vec2_Lerp (Vec2 a, Vec2 b, float t)
	Linearly interpolate between two vectors.
Vec2	Vec2_RotateDegrees (Vec2 v, float angle)
	Rotate a vector by an angle in degrees.
Vec2	Vec2_RotateRadians (Vec2 v, float angle)
	Rotate a vector by an angle in radians.
Vec2	Vec2_RotateAroundRadians (Vec2 point, Vec2 center, float angle)
	Rotate a point around a center by an angle in radians.
Vec2	Vec2_RotateAroundDegrees (Vec2 point, Vec2 center, float angle)
	Rotate a point around a center by an angle in degrees.
SDL_Rect	Vec2_ToRect (Vec2 position, Vec2 size)
	Convert a position and size to an SDL_Rect.
SDL_Rect	Vec2_ToCenteredRect (Vec2 position, Vec2 size)
	Convert a position and size to a centered SDL_Rect.
Vec2	Vec2_ToCenteredPosition (Vec2 position, Vec2 size)
	Convert a position and size to a centered position.
void	Vec2_FromRect (SDL_Rect rect, Vec2 *position, Vec2 *size)
	Extract position and size from an SDL_Rect.
Vec2	Vec2_Clamp (Vec2 v, Vec2 min, Vec2 max)
	Clamp a vector between two vectors.
Vec2	Vec2_Max (Vec2 a, Vec2 b)
	Get the maximum of two vectors.
Vec2	Vec2_Min (Vec2 a, Vec2 b)
	Get the minimum of two vectors.
Vec2	Vec2_Abs (Vec2 v)
	Get the absolute value of a vector.
Vec2	Vec2_FromPoint (SDL_Point point)
	Convert an SDL_Point to a Vec2.
SDL_Point	Vec2_ToPoint (Vec2 v)
	Convert a Vec2 to an SDL_Point.
bool	Vec2_AreEqual (Vec2 a, Vec2 b)
Vec2	Vec2_Square (float side)
SDL_Rect	Vec2_ToSquareRect (Vec2 position, float side)
SDL_Rect	Vec2_ToCenteredSquareRect (Vec2 position, float side)
float	Vec2_AngleBetween (Vec2 a, Vec2 b)
	Calculates the angle between two vectors in degrees.

Detailed Description

Provides 2D vector functionality for positions, directions, and transformations.

Being a top down 2D game, the Vec2 struct can be used to represent:

• Positions
• Velocities
• Directions
• Sizes
• Offsets
• And so on

The functions in this file can be used to perform common vector operations such as addition, subtraction, normalization, and rotation.

Usage Examples

Usage Examples1. Movement calculations:

Vec2 position = {10, 20};
Vec2 velocity = {5, 0};
 
// Move the position by the velocity
position = Vec2_Add(position, velocity);

2. Move towards a target:

Vec2 position = {10, 20};
Vec2 target = {100, 50};
float speed = 5;
 
// Calculate the direction to the target (Read more about Vec2_Normalize)
Vec2 direction = Vec2_Normalize(Vec2_Subtract(target, position));
 
// Move towards the target
position = Vec2_Add(position, Vec2_Multiply(direction, speed));

3. Rendering a rectangle:

Vec2 position = {100, 200};
Vec2 size = {50, 50};
SDL_Rect renderRect = Vec2_ToRect(position, size);
SDL_SetRenderDrawColor(app.resources.renderer, 255, 0, 0, 255);
SDL_RenderFillRect(app.resources.renderer, &renderRect);

In this case, the position (100, 200) represent where the top-left corner of the rectangle will be rendered.

If you want to render the rectangle centered around the position, you can use Vec2_ToCenteredRect:

// ...
SDL_Rect = Vec2_ToCenteredRect(position, size);
// ...

Here's a visualization of this:

Author

Mango

Date

2025-02-28

Typedef Documentation

Vec2

typedef struct Vec2 Vec2

Function Documentation

Vec2_Abs()

Vec2 Vec2_Abs

(

Vec2

v

)

Get the absolute value of a vector.

Parameters

v	The vector

Returns

The absolute value vector

Get the absolute value of a vector.

Parameters

v	The vector to compute absolute values for.

Returns

A vector where each component is the absolute value of v.

Vec2_Add()

Vec2 Vec2_Add	(	Vec2	a,
		Vec2	b
	)

Add two vectors.

Parameters

a	First vector
b	Second vector

Returns

The resulting vector

Add two vectors.

Parameters

a	The first vector.
b	The second vector.

Returns

The resulting vector from a + b.

Vec2_AngleBetween()

float Vec2_AngleBetween	(	Vec2	a,
		Vec2	b
	)

Calculates the angle between two vectors in degrees.

Parameters

a	The first vector.
b	The second vector.

Returns

The angle in degrees between the two vectors. This means that Vec2_RotateDegrees(a, angle) will be equal to b.

Vec2_AreEqual()

bool Vec2_AreEqual	(	Vec2	a,
		Vec2	b
	)

Vec2_Clamp()

Vec2 Vec2_Clamp	(	Vec2	v,
		Vec2	min,
		Vec2	max
	)

Clamp a vector between two vectors.

Parameters

v	The vector to clamp
min	The minimum vector
max	The maximum vector

Returns

The clamped vector

Clamp a vector between two vectors.

Ensures the vector's components stay within the provided bounds.

Parameters

v	The vector to clamp.
min	The minimum values.
max	The maximum values.

Returns

The clamped vector.

Vec2_Decrement()

Vec2 Vec2_Decrement	(	Vec2 *	a,
		Vec2	b
	)

Decrement vector a by vector b.

Parameters

a	Pointer to the first vector
b	Second vector

Returns

The decremented vector

Decrement vector a by vector b.

Parameters

a	Pointer to the vector to decrement.
b	The vector by which a will be decremented.

Returns

The updated vector a after subtraction.

Vec2_Distance()

float Vec2_Distance	(	Vec2	a,
		Vec2	b
	)

Calculate the distance between two vectors.

Parameters

a	First vector
b	Second vector

Returns

The distance as a float

Calculate the distance between two vectors.

Magnitude is the length of a vector.

Parameters

v	The vector to get the magnitude of.

Returns

The magnitude (length) of vector v.

Vec2_Divide()

Vec2 Vec2_Divide	(	Vec2	v,
		float	scalar
	)

Divide a vector by a scalar.

Parameters

v	The vector
scalar	The scalar value

Returns

The resulting vector

Divide a vector by a scalar.

Parameters

v	The vector to divide.
scalar	The scalar divisor.

Returns

The resulting vector v / scalar.

Vec2_Dot()

float Vec2_Dot	(	Vec2	a,
		Vec2	b
	)

Calculate the dot product of two vectors.

Parameters

a	First vector
b	Second vector

Returns

The dot product as a float

Calculate the dot product of two vectors.

Parameters

a	The first vector.
b	The second vector.

Returns

The dot product (a.x * b.x + a.y * b.y).

Vec2_FromPoint()

Vec2 Vec2_FromPoint

(

SDL_Point

point

)

Convert an SDL_Point to a Vec2.

Parameters

point

The SDL_Point

Returns

The resulting Vec2

Convert an SDL_Point to a Vec2.

Parameters

point

The SDL_Point to convert.

Returns

The corresponding Vec2.

Vec2_FromRect()

void Vec2_FromRect	(	SDL_Rect	rect,
		Vec2 *	position,
		Vec2 *	size
	)

Extract position and size from an SDL_Rect.

Parameters

rect	The SDL_Rect
position	Pointer to the position vector
size	Pointer to the size vector

Extract position and size from an SDL_Rect.

Parameters

rect	The SDL_Rect to decompose.
position	Pointer to store the position.
size	Pointer to store the size.

Vec2_Increment()

Vec2 Vec2_Increment	(	Vec2 *	a,
		Vec2	b
	)

Increment vector a by vector b.

Parameters

a	Pointer to the first vector
b	Second vector

Returns

The incremented vector

Increment vector a by vector b.

Parameters

a	Pointer to the vector to increment.
b	The vector to add.

Returns

The updated vector a (a + b).

Vec2_Lerp()

Vec2 Vec2_Lerp	(	Vec2	a,
		Vec2	b,
		float	t
	)

Linearly interpolate between two vectors.

Parameters

a	First vector
b	Second vector
t	Interpolation factor (0 to 1)

Returns

The interpolated vector

Linearly interpolate between two vectors.

Parameters

a	The start vector.
b	The destination vector.
t	The interpolation factor (0.0 to 1.0).

Returns

The interpolated vector between a and b.

Vec2_Magnitude()

float Vec2_Magnitude

(

Vec2

v

)

Calculate the magnitude (length) of a vector.

Parameters

v	The input vector

Returns

The magnitude as a float

Calculate the magnitude (length) of a vector.

Magnitude is the length of a vector.

Parameters

v	The vector to get the magnitude of.

Returns

The magnitude (length) of vector v.

Vec2_Max()

Vec2 Vec2_Max	(	Vec2	a,
		Vec2	b
	)

Get the maximum of two vectors.

Parameters

a	First vector
b	Second vector

Returns

The maximum vector

Get the maximum of two vectors.

Parameters

a	The first vector.
b	The second vector.

Returns

A vector of max components.

Vec2_Min()

Vec2 Vec2_Min	(	Vec2	a,
		Vec2	b
	)

Get the minimum of two vectors.

Parameters

a	First vector
b	Second vector

Returns

The minimum vector

Get the minimum of two vectors.

Parameters

a	The first vector.
b	The second vector.

Returns

A vector of min components.

Vec2_Multiply()

Vec2 Vec2_Multiply	(	Vec2	v,
		float	scalar
	)

Multiply a vector by a scalar.

Parameters

v	The vector
scalar	The scalar value

Returns

The resulting vector

Multiply a vector by a scalar.

Parameters

v	The vector to multiply.
scalar	The scalar multiplier.

Returns

The resulting vector v * scalar.

Vec2_Normalize()

Vec2 Vec2_Normalize

(

Vec2

v

)

Normalize a vector (make it unit length)

Parameters

v	The vector to normalize

Returns

The normalized vector

Normalize a vector (make it unit length)

A normalized vector has a magnitude of 1 and the same direction as v.

Parameters

v	The vector to normalize.

Returns

The normalized vector of v.

Vec2_RotateAroundDegrees()

Vec2 Vec2_RotateAroundDegrees	(	Vec2	point,
		Vec2	center,
		float	angle
	)

Rotate a point around a center by an angle in degrees.

Parameters

point	The point to rotate
center	The center of rotation
angle	The angle in degrees

Returns

The rotated point

Rotate a point around a center by an angle in degrees.

Parameters

point	The point to rotate.
center	The pivot for rotation.
angle	The rotation angle in degrees.

Returns

The rotated point.

Vec2_RotateAroundRadians()

Vec2 Vec2_RotateAroundRadians	(	Vec2	point,
		Vec2	center,
		float	angle
	)

Rotate a point around a center by an angle in radians.

Parameters

point	The point to rotate
center	The center of rotation
angle	The angle in radians

Returns

The rotated point

Rotate a point around a center by an angle in radians.

Translates the point to origin-relative, rotates it, then translates back.

Parameters

point	The point to rotate.
center	The pivot for rotation.
angle	The rotation angle in radians.

Returns

The rotated point.

Vec2_RotateDegrees()

Vec2 Vec2_RotateDegrees	(	Vec2	v,
		float	angle
	)

Rotate a vector by an angle in degrees.

Parameters

v	The vector
angle	The angle in degrees

Returns

The rotated vector

Rotate a vector by an angle in degrees.

Parameters

v	The vector to rotate.
angle	The angle in degrees.

Returns

The rotated vector.

Vec2_RotateRadians()

Vec2 Vec2_RotateRadians	(	Vec2	v,
		float	angle
	)

Rotate a vector by an angle in radians.

Parameters

v	The vector
angle	The angle in radians

Returns

The rotated vector

Rotate a vector by an angle in radians.

Parameters

v	The vector to rotate.
angle	The angle to rotate by in radians.

Returns

The rotated vector.

Vec2_Square()

Vec2 Vec2_Square

(

float

side

)

Vec2_Subtract()

Vec2 Vec2_Subtract	(	Vec2	a,
		Vec2	b
	)

Subtract vector b from vector a.

Parameters

a	First vector
b	Second vector

Returns

The resulting vector

Subtract vector b from vector a.

Parameters

a	The vector to subtract from.
b	The vector to subtract.

Returns

The result of a - b.

Vec2_ToCenteredPosition()

Vec2 Vec2_ToCenteredPosition	(	Vec2	position,
		Vec2	size
	)

Convert a position and size to a centered position.

Parameters

position	The position vector
size	The size vector

Returns

The resulting centered position vector

Convert a position and size to a centered position.

Useful for positioning sprites centered on a coordinate.

Parameters

position	The top-left position.
size	The size of the object.

Returns

The centered position.

Vec2_ToCenteredRect()

SDL_Rect Vec2_ToCenteredRect	(	Vec2	position,
		Vec2	size
	)

Convert a position and size to a centered SDL_Rect.

Parameters

position	The position vector
size	The size vector

Returns

The resulting centered SDL_Rect

Convert a position and size to a centered SDL_Rect.

Centers the rect at the specified position.

Parameters

position	The center position.
size	The width and height.

Returns

A centered SDL_Rect.

Vec2_ToCenteredSquareRect()

SDL_Rect Vec2_ToCenteredSquareRect	(	Vec2	position,
		float	side
	)

Vec2_ToPoint()

SDL_Point Vec2_ToPoint

(

Vec2

v

)

Convert a Vec2 to an SDL_Point.

Parameters

v	The vector

Returns

The resulting SDL_Point

Convert a Vec2 to an SDL_Point.

Parameters

v	The Vec2 to convert.

Returns

The corresponding SDL_Point.

Vec2_ToRect()

SDL_Rect Vec2_ToRect	(	Vec2	position,
		Vec2	size
	)

Convert a position and size to an SDL_Rect.

Parameters

position	The position vector
size	The size vector

Returns

The resulting SDL_Rect

Convert a position and size to an SDL_Rect.

Parameters

position	The top-left position.
size	The width and height.

Returns

The SDL_Rect corresponding to position and size.

Vec2_ToSquareRect()

SDL_Rect Vec2_ToSquareRect	(	Vec2	position,
		float	side
	)