Docs/Animation

Available since v0.6.0

Chitra supports creating 2D animations by generating PNG images for each frame and converting them into an animation file by calling the ffmpeg command.

Call the endFrame() command to finish a frame and start a new one. Finally, call the saveAs() command to save it in the required format (GIF, MP4, MOV, or WEBM).

Chitra will create a PNG image for each frame in the .frames directory. These frames will be deleted once the final output is generated. To keep these temporary files for inspection (Don’t delete after generating the final output), call the keepTemporaryFrames() command.

background("white");
noStroke;
auto x = 0;
foreach(i; 0 .. 60)
{
    rect(x, 20, 20);
    endFrame;
    x += 10;
}
saveAs("expanding-rect.gif");

Source

To clear the canvas after drawing a frame, pass clear: true while calling the endFrame command.

auto x = 0;
foreach(i; 0 .. 60)
{
    background("white");
    noStroke;
    rect(x, 20, 20);
    endFrame(clear: true);
    x += 10;
}
saveAs("moving-rect.gif");

Source

It is possible to customise the frame duration of each frame by specifying frameDuration before calling the endFrame command. Once set, the same frame duration will be applied to all future frames. To set a Frame duration for all frames, call frameDuration before starting any frames or call the frameRate command.

frameRate(10); // Set default frame rate
auto x = 0;
foreach (i; 0 .. 60)
{
    rect(x, 20, 20);
    // Change the frame duration for the 7th frame
    if (i == 7)
        frameDuration(2);

    endFrame;
    x += 10;
    // Reset the frame duration to
    // default for the future frames
    frameRate(10);
}

saveAs("expanding-rect-with-pause.gif");

Source

Chitra provides text variables that can be used within the text; the following variables are available for use with animation.

totalFrames;
currentFrame;

Example:

text("/", 10, 10);

To disable loop while saving GIF.

saveAs("moving-rect-no-loop.gif");

Source

Supported save formats:

• GIF format saveAs("moving_rect.gif");
• MP4 format saveAs("moving_rect.mp4");
• MOV format saveAs("moving_rect.mov");
• WEBM format saveAs("moving_rect.webm");