Collaboration diagram for Shaders:

Macros
#define	BJ_SHADER_STANDARD_FLAGS (BJ_SHADER_INVERT_Y \| BJ_SHADER_CLAMP_COLOR \| BJ_SHADER_NORMALIZE_COORDS \| BJ_SHADER_CENTER_COORDS)

Typedefs
typedef int(*	bj_bitmap_shading_fn_t) (bj_vec3 out_color, const bj_vec2 pixel_coord, void *user_data)
typedef enum bj_shader_flag_t	bj_shader_flag

Enumerations
enum	bj_shader_flag_t { BJ_SHADER_INVERT_X = 0x01 , BJ_SHADER_INVERT_Y = 0x02 , BJ_SHADER_CLAMP_COLOR = 0x04 , BJ_SHADER_NORMALIZE_COORDS = 0x08 , BJ_SHADER_CENTER_COORDS = 0x10 }

Functions
void	bj_shader_bitmap (bj_bitmap p_bitmap, bj_bitmap_shading_fn_t p_shader, void p_data, uint8_t flags)

Detailed Description

Software shader-like API for bj_bitmap.

This API provides facilities to manipulate the pixels of a bj_bitmap object in a similar way GPU shaders do.

A shader function is any user-provided function that corresponds to the bj_bitmap_shading_fn_t signature. Such function is passed to bj_shader_bitmap which calls the shader fonction on every pixel of the bitmap.

Useful math-related functions can be found in math.h.

Macro Definition Documentation

◆ BJ_SHADER_STANDARD_FLAGS

#define BJ_SHADER_STANDARD_FLAGS (BJ_SHADER_INVERT_Y | BJ_SHADER_CLAMP_COLOR | BJ_SHADER_NORMALIZE_COORDS | BJ_SHADER_CENTER_COORDS)

Flagset alias for bj_shader_bitmap.

This flagset value can be passed to bj_shader_bitmap and corresponds to the most commonly used flags:

Invert Y (orient from bottom-left corner),
Clamp color between 0.0 and 1.0,
Convert pixel coordinates in the [-1.0 ; 1.0] space

Typedef Documentation

◆ bj_bitmap_shading_fn_t

typedef int(* bj_bitmap_shading_fn_t) (bj_vec3 out_color, const bj_vec2 pixel_coord, void *user_data)

Function type for a bitmap shading operation.

A shader function pointer is provided to bj_shader_bitmap and will be called for each pixel of the provided bitmap.

Parameters

out_color	Pointer to the output color (in linear RGB space).
pixel_coord	Position of the pixel in 2D coordinates.
user_data	Optional user data passed through from bj_shader_bitmap.

Returns: 1 on success, non-zero if the pixel should be skipped or discarded.

◆ bj_shader_flag

typedef enum bj_shader_flag_t bj_shader_flag

Shader input control flags.

These flags are passed to bj_shader_bitmap to control how the inputs to the shader function (bj_bitmap_shading_fn_t) are transformed. They affect how the pixel coordinates are interpreted and how the shader's output color is handled.

Enumeration Type Documentation

◆ bj_shader_flag_t

enum bj_shader_flag_t

Shader input control flags.

These flags are passed to bj_shader_bitmap to control how the inputs to the shader function (bj_bitmap_shading_fn_t) are transformed. They affect how the pixel coordinates are interpreted and how the shader's output color is handled.

Enumerator
BJ_SHADER_INVERT_X	Invert the X coordinate of the input pixel. By default, the coordinate system matches that of bj_bitmap. The origin is at the top-left corner, with X increasing to the right and Y increasing downward, ranging from 0 to the bitmap's width and height. When this flag is set, the X coordinate is mirrored as if the bitmap were flipped horizontally. This flag can be combined with BJ_SHADER_NORMALIZE_COORDS and BJ_SHADER_CENTER_COORDS. It is applied after those transformations.
BJ_SHADER_INVERT_Y	Invert the Y coordinate of the input pixel. By default, the coordinate system matches that of bj_bitmap. The origin is at the top-left corner, with X increasing to the right and Y increasing downward, ranging from 0 to the bitmap's width and height. When this flag is set, the Y coordinate is mirrored as if the bitmap were flipped vertically. This flag can be combined with BJ_SHADER_NORMALIZE_COORDS and BJ_SHADER_CENTER_COORDS. It is applied after those transformations.
BJ_SHADER_CLAMP_COLOR	Clamp the output color to the range [0.0, 1.0]. The shader function is expected to output RGB components in the range [0.0, 1.0]. If this flag is set, the output color will automatically be clamped to that range, preventing overflow or underflow. This can help avoid artifacts if the shader generates values outside the valid range.
BJ_SHADER_NORMALIZE_COORDS	Normalize pixel coordinates to the [0.0, 1.0] range. Converts the pixel's X and Y coordinates into normalized values between 0.0 and 1.0, based on the width and height of the bitmap. This transformation maintains the original orientation (top-left origin), unless combined with BJ_SHADER_INVERT_X or BJ_SHADER_INVERT_Y. If used together with BJ_SHADER_CENTER_COORDS, the final coordinate space becomes [-1.0, 1.0], centered around the origin.
BJ_SHADER_CENTER_COORDS	Center pixel coordinates around the origin. Translates the coordinate system so that (0,0) represents the center of the bitmap. By default, pixel coordinates range from (0,0) to (width, height). When this flag is enabled: If used without BJ_SHADER_NORMALIZE_COORDS, coordinates are shifted into the range: X: [-width/2, width/2] Y: [-height/2, height/2] If used with BJ_SHADER_NORMALIZE_COORDS, coordinates are shifted into the range: X, Y ∈ [-1.0, 1.0] This transformation is applied before coordinate inversion flags.

Function Documentation

◆ bj_shader_bitmap()

void bj_shader_bitmap	(	bj_bitmap *	p_bitmap,
		bj_bitmap_shading_fn_t	p_shader,
		void *	p_data,
		uint8_t	flags )

Applies a shader function to every pixel in a bitmap.

The shader function is called per pixel, with access to the 2D coordinate and a reference to output a linear RGB color. Optional user data and behavior flags can be provided.