Draw Pixels

Defold engine native extension for drawing pixels and simple geometry into texture buffer.

Feel free to contribute!

Please, pay attension! The size of the image you manipulate with DrawPixels must match that of the atlas, not the sprite image. Otherwise you need to know where the sprite is the atlas and update that region of the atlas.

Installation

You can use the Draw Pixels extension in your own project by adding this project as a Defold library dependency. Open your game.project file and in the dependencies field under project add:

https://github.com/AGulev/drawpixels/archive/master.zip

Example

Main code example is here

Lua API

First of all you need to create a table with a buffer information that contain next fields:

buffer - buffer
width - buffer width, same as your texture width
height - buffer height, same as your texture height
channels - 3 for rgb, 4 for rgba
premultiply_alpha - alpha value will be premultiplied into the RGB color values. Optional parameter. Default is false.

For example:

local buffer_info = {
    buffer = buffer.create(1024 * 2048, -- size of the buffer width*height
    {{
      name = hash("my_buffer"),
      type = buffer.VALUE_TYPE_UINT8,
      count = 4 -- same as channels
    }}),
    width = 1024,
    height = 2048,
    channels = 4,
    premultiply_alpha = true
  }

Then when you have a buffer info, you can use next methods:

drawpixels.circle(buffer_info, pox_x, pox_y, diameter, red, green, blue, alpha, antialiasing, width)

Method for drawing circle:

buffer_info - buffer information
pox_x - x position center of the circle
pox_y - y position center of the circle
diameter - diameter of the circle
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures
antialiasing - adds anti-aliasing. Only for 4 channels. Optional parameter.
width - indicates the circle width. Only for circle with anti-aliasing. Optional parameter.

drawpixels.filled_circle(buffer_info, pos_x, pos_y, diameter, red, green, blue, alpha, antialiasing)

Method for drawing filled circle:

drawpixels.rect(buffer_info, pos_x, pos_y, rect_width, rect_height, red, green, blue, alpha)

Method for drawing rectangle:

buffer_info - buffer information
pox_x - x position center of the rectangle
pox_y - y position center of the rectangle
rect_width - rectangle width
rect_height - rectangle height
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures

drawpixels.filled_rect(buffer_info, pos_x, pos_y, rect_width, rect_height, red, green, blue, alpha, angle)

Method for drawing filled rectangle:

drawpixels.fill(buffer_info, red, green, blue, alpha)

Fill buffer with the color:

buffer_info - buffer information
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures

drawpixels.line(buffer_info, x0, y0, x1, y1, red, green, blue, alpha, antialiasing, width)

Draw a line between two points:

buffer_info - buffer information
x0 - x position of one end of the line
y0 - y position of one end of the line
x1 - x position of the other end of the line
y1 - y position of the other end of the line
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures
antialiasing - adds anti-aliasing. Only for 4 channels. Optional parameter.
width - indicates the line width. Only for line with anti-aliasing. Optional parameter.

drawpixels.gradient_line(buffer_info, x0, y0, x1, y1, red1, green1, blue1, red2, green2, blue2, alpha, antialiasing, width)

Draw a gradient line between two points:

buffer_info - buffer information
x0 - x position of one end of the line
y0 - y position of one end of the line
x1 - x position of the other end of the line
y1 - y position of the other end of the line
red1 - first red channel of the color 0..255
green1 - first green channel of the color 0..255
blue1 - first blue channel of the color 0..255
red2 - second red channel of the color 0..255
green2 - second green channel of the color 0..255
blue2 - second blue channel of the color 0..255
alpha - alpha channel 0..255
antialiasing - adds anti-aliasing. Only for 4 channels. Optional parameter.
width - indicates the line width. Only for line with anti-aliasing. Optional parameter.

drawpixels.arc(buffer_info, x, y, radius, from, to, red, green, blue, alpha)

Draw a arc between two corners. If from < to the arc is drawn counterclockwise. If from > to the arc is drawn clockwise. Only for 4 channels:

buffer_info - buffer information
x - x position center of the circle
y - y position center of the circle
radius - radius of the circle
from - first arc angle in radians. May be negative
to - second arc angle in radians. May be negative
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255

drawpixels.filled_arc(buffer_info, x, y, radius, from, to, red, green, blue, alpha)

Draw a filled arc between two corners. If from < to the arc is drawn counterclockwise. If from > to the arc is drawn clockwise. Only for 4 channels:

drawpixels.gradient_arc(buffer_info, x, y, radius, from, to, red1, green1, blue1, red2, green2, blue2, alpha)

Draw a gradient arc between two corners. If from < to the arc is drawn counterclockwise. If from > to the arc is drawn clockwise. Only for 4 channels:

buffer_info - buffer information
x - x position center of the circle
y - y position center of the circle
radius - radius of the circle
from - first arc angle in radians. May be negative
to - second arc angle in radians. May be negative
red1 - first red channel of the color 0..255
green1 - first green channel of the color 0..255
blue1 - first blue channel of the color 0..255
red2 - second red channel of the color 0..255
green2 - second green channel of the color 0..255
blue2 - second blue channel of the color 0..255
alpha - alpha channel 0..255

drawpixels.pixel(buffer_info, x, y, red, green, blue, alpha)

Draw a pixel:

buffer_info - buffer information
x - x position of pixel
y - y position of pixel
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures

drawpixels.color(buffer_info, x, y)

Read color from a position in the buffer:

buffer_info - buffer information
x - x position to get color from
y - y position to get color from

RETURNS:

red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures

drawpixels.bezier(buffer_info, x0, y0, xc, yc, x1, y1, red, green, blue, alpha)

Draw a bezier line between two points and one control point:

buffer_info - buffer information
x0 - x position of the first point
y0 - y position of the first point
xc - x position of the control point
yc - y position of the control point
x1 - x position of the second point
y1 - y position of the second point
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255. Optional parameter for rgba textures

You can fill in a specific area. To do this, you need to identify the borders with start_fill method and call the fill_area method to fill the area. Borders work with: lines, gradient lines, circles, filled circles with anti-aliasing, pixels, arcs. NOT WORK WITH FILLED ARCS AND GRADIENT ARCS. The arcs themselves use this method, so the fill may not be predictable. Do not create arcs until you are done with the fill. Be sure to call the end_fill method when you stop working with the fill.

drawpixels.start_fill()

Indicates the start of border preservation.

drawpixels.end_fill()

Indicates the stop of border preservation.

drawpixels.fill_area(buffer_info, x, y, red, green, blue, alpha)

Fills an area at specified boundaries. Only for 4 channels:

buffer_info - buffer information
x - x position of the start point
y - y position of the start point
red - red channel of the color 0..255
green - green channel of the color 0..255
blue - blue channel of the color 0..255
alpha - alpha channel 0..255

In order to draw this into a sprite, you need a separate atlas with power of two texture. Then we can use resource.set_texture:

resource.set_texture(go.get("#sprite", "texture0"), self.header, self.buffer_info.buffer)

In order to render this in gui, we just need to create a box and create a new texture. We can use gui.new_texture. Then you need to set this texture to the box using gui.set_texture:

local data = buffer.get_bytes(self.buffer_info.buffer, hash("rgba"))
gui.new_texture("name", width, height, image.TYPE_RGBA, data)
gui.set_texture(gui.get_node("box"), "name")
gui.set_size(gui.get_node("box"), vmath.vector3(width, height, 0))

If you have any questions or suggestions contact me: [email protected]

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