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BlidDev edited this page Jan 9, 2024 · 3 revisions

Overview:

Niv comes with a simple pixel canvas API, and this chapter will explain how to use it.

The way it works: The canvas has 2 pixel buffers, one for display and one for drawing. When you're editing your canvas, you're actually editing the drawing buffer. Then, when your frame is ready to be shown to the screen, you can run apply in order to copy the drawing buffer into the display one, meaning your changes can actually be shown.

This is done in order to reduce SFML draw calls as much as possible to save on computing power and unwanted visual gitches.

init

usage example:

// template
init w_w w_h c_w c_h title

// specific use
init 854 480 16 9 "An example window"

Args:

  • w_w: I32
  • w_h: I32
  • c_w: I32
  • c_h: I32
  • title: STR or CHAR

Desc:

Initilizes SGL's graphics context and creates a new window w_wxw_h pixels large with a c_wxc_h size pixel canvas.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_clear

usage example:

// template
set_clear r g b

// specific use
set_clear 255 19 (cal 120 / 2)

Args:

  • r: I32 (0 - 255)
  • g: I32 (0 - 255)
  • b: I32 (0 - 255)

Desc:

Sets the canvas clear color to the given r g b values.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

clear

usage example:

clear

Desc:

Clears the canvas and sets it to the given clear_color.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

apply

usage example:

apply

Desc:

Copies the data from the drawing pixel buffer into the display one.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

display

usage example:

display

Desc:

Renders the display pixel buffer onto the screen, allowing the image to actually show.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_pixel

usage example:

// template
set_pixel x y r g b

// specific use
set_pixel 4 8 (cal 1 * 255) 150 200

Args:

  • x: I32
  • y: I32
  • r: I32 (0 - 255)
  • g: I32 (0 - 255)
  • b: I32 (0 - 255)

Desc:

Sets the pixel at [x, y] in the drawing pixel buffer to the given [r, g, b] values.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_area

usage example:

// template
set_area x y w h r g b

// specific use
set_area 4 3 2 3 50 50 50

Args:

  • x: I32
  • y: I32
  • w: I32
  • h: I32
  • r: I32 (0 - 255)
  • g: I32 (0 - 255)
  • b: I32 (0 - 255)

Desc:

Sets a w by h area at [x, y] in the drawing pixel buffer to the given [r, g, b] values.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

get_pixel

usage example:

// template
get_pixel x y r g b

// specific use
set r  ""
set g  ""
set b  ""
get_pixel 1 1 r g b

Args:

  • x: I32
  • y: I32
  • r: STR or CHAR
  • g: STR or CHAR
  • b: STR or CHAR

Desc:

Opposite of set_pixel; retrieves the rgb values of a pixel at (x, y) in the drawing pixel buffer and stores it inside the given variables.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

get_area

usage example:

// template
get_area x y w h

// specific use
set lst (get_area 1 1 3 3)

Desc:

Opposite of set_area; retrieves the rgb values of a w by h area at (x, y) in the drawing pixel buffer and returns it as a LIST containing all of the values from the given area in RGBA8888 pixel format.

Return value: List of I32s.

For more complex examples check one of the graphical examples in the examples folder.

get_millis

usage example:

get_millis

Desc:

Returns the amount of milliseconds that passed since the initilization of the graphical context.

Return value: I32.

For more complex examples check one of the graphical examples in the examples folder.

load_font

usage example:

// template
load_font path

// specific use
load_font "path/to/font.ttf"

Desc:

Loads a font from a file to be used by all text objects in the program.

Return value: I32.

For more complex examples check one of the graphical examples in the examples folder.

new_text

usage example:

// template
new_text msg scale

// specific use
set text1 (new_text (format "hello {}" "world!") 45)

Args:

  • msg: STR
  • scale: I32

Desc:

Creates a new text object with msg as its body with size scale (in pixels) at (0, 0) and returns its ID to be saved.

Return value: I32.

For more complex examples check one of the graphical examples in the examples folder.

set_ttext

usage example:

// template
set_ttext id msg

// specific use
set_ttext $text1 "Different message\n"

Args:

  • id: I32
  • msg: STR

Desc:

Sets the text of text object with id id to msg.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_tsize

usage example:

// template
set_tsize id size

// specific use
set_tsize $text1 (cal 10 * 3)

Args:

  • id: I32
  • size: I32

Desc:

Sets the size of text object with id id to size (in pixels).

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_tpos

usage example:

// template
set_tpos id x y

// specific use
set_tpos $text2 (cal 50 / 5) 100

Args:

  • id: I32
  • x: I32
  • y: I32

Desc:

Sets the position of text object with id id to (x, y) (in pixels).

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_tclr

usage example:

// template
set_tclr id r g b

// specific use
set_tclr $text1 100 100 50

Args:

  • id: I32
  • r: I32
  • g: I32
  • b: I32

Desc:

Sets the color of text object with id id to (r, g, b).

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

set_tvisible

usage example:

// template
set_tvisible id flag

// specific use
set_tvisible $text1 false

Args:

  • id: I32
  • flag: BOOL

Desc:

Sets whether text object with id id should be visible.

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

end_text

usage example:

// template
end_text id 

// specific use
end_text text1 // notice no $

Args:

  • id: STR or CHAR

Desc:

Deletes the text object with id id and sets the variable containing the id to VOID

Return value: VOID.

For more complex examples check one of the graphical examples in the examples folder.

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