Pena Contents
  • Compatible Devices
  • About The Name
  • Basic Features
  • Restrictions
  • The Canvas
  • Using Panes
  • How Painting Works
  • A Complete Effects List
  • Example Effects Program
  • Online Video Tutorials
    Control Pane
    Brush Pane
    Texture Pane
    Effects Pane
    Color Picker
    Save/Load Pane
    Selection Pane
    Preferences Pane
    Intelligent Canvas
    Wacom Bluetooth Stylus
    Jot Bluetooth Stylus
    The Effects Library
    Effects Introduction
    Color Source Effects
    Procedural Source Effects
    Color Filter Effects
    Spatial Filter Effects
    Math and Logic Effects
    Special Effects
    Artists Gallery
    The Artist Gallery
    Pena Support


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      Compatible Devices

      The more powerful your tablet, the faster and better Pena will run - especially when painting with complex Effects.

      An iPad Air is the most recommended device. Pena will also work on 3rd and 4th generation iPads.

      We do not recommend running Pena on a 2nd generation iPad. And Pena is incompatible with 1st generation iPads.

      As a note, the majority of Pena was developed using a 3rd generation iPad (until the iPad Air came out).

      The iPad Air has an extremely fast GPU and also runs openGL ES 3.0 (whereas 2nd, 3rd, and 4th generation iPads run openGL ES 2.0). Pena currently takes advantage of openGL ES 3.0, if it is available on the device.


      About The Name

      Pena is the Hawaiian word for painting. The proper way to say the word is pen-ah.


      Basic Features

      Pena is unlike any other 2D paint system you have ever experienced. Painting with Pena allows you to create nearly infinite styles and Effects.

      As you will see, Pena also introduces several new concepts to computer painting, such as Programmable Brushes and Intelligent Canvas.

      Here is a brief description of the basic feature set in Pena:

      • Programmable Brushes - Brushes in Pena consist of Effects that you add to your brush. A brush can have up to 32 Effects, the order and settings of which determine exactly what you are painting. For example, you might combine a 4-color gradient with polka-dots and a spiral pattern and use that as your paint.
      • Intelligent Canvas - An advanced feature in Pena lets you setup your canvas to know that it has properties. For example, you could specify that a particular part of the canvas is always tinted blue, regardless of what you are painting on it.
      • Powerful Effects - Programmable Brushes and Intelligent Canvas Effects are all openGL Shaders. Pena comes with a healthy selection of Effects separated into into these six categories: Color Sources, Procedural Sources, Color Filters, Spatial Filters, Math and Logic, and Special Effects.
      • Textures - Pena lets you work with photos and images from your Photo Album. Effects can use up to five textures simultaneously to create complex and varied paint. Pena can also be used to image process images and add an infinite amount of effects.
      • Brush Properties - Pena comes with round, oval, square, and rectangular brushes. A brush can be sized from a point to larger than the screen. Brushes can be rotated, tapered, and offset. Rotation and tapering can change dynamically over time. An Airbrush is available by using the Airbrush Spatial Shader.
      • Text and Masks - Pena lets you create selection masks which lets you specify which parts of the canvas can be painted on, and which can not. Selection masks can also be used to create text using any of the hundreds of built-in iPad fonts.
      • Extensive Save and Load - Pena has four independent saving and loading mechanisms. Favorite brushes can be saved and loaded. Favorite brush and surface Effects can be saved and loaded. And finally, all aspects to the current painting can be saved and loaded. Painting aspects can be selected and merged with other paintings.
      • Wacom Bluetooth Stylus Support - Pena supports Wacom Bluetooth Stylus for iPad, such as the Wacom Intuos Creative Stylus (supports Pressure and Shortcuts). Only on iPad Mini, iPad 3, 4, iPad Air, and above.
      • Jot Bluetooth Stylus Support - Pena supports Jot Bluetooth Stylus for iPad, such as the Jot Touch 4 Stylus (supports Pressure and Shortcuts). Only on iPad Mini, iPad 3, 4, iPad Air, and above.


      While Pena is a very comprehensive paint system, there are a few restrictions and limits of what you can do:

      • openGL ES - Pena is built on openGL ES, the same graphics powerhouse behind iPad games. However, openGL ES has certain restrictions that also restricts what Pena can do. An example of this is that Pena can not use what you are painting while you are painting it (such as dynamic feedback). However, Pena does let you use what you just finished drawing as you continue drawing (delayed feedback).
      • Resolution - Pena is built to treat the iPad screen as the entire canvas. Because painting speed is always an issue, the current version of Pena does not support painting at the Retina screen resolution. Thus, with the current version of Pena the canvas is always 1024 x 768 (landscape) or 768 x 1024 (portrait).
      • Pinch To Zoom - Currently Pena does not have a Pinch-To-Zoom feature. It did not seem necessary - as painting on a real Canvas does not require that capability either. However, we may decide to add this in a future release.

      Understanding The Canvas

      Pena mimics real-life painting in terms of the canvas. If you are painting on a real canvas, the painting is attached to the canvas. Rotating the canvas rotates the painting as well.

      Pena duplicates this by fixing the painting to the iPad regardless of the orientation of the device.

      When you start a painting in Pena, you might pick landscape, or portrait, depending on what you have in mind.

      The controls will always rotate to the way you are holding the device. However, the painting itself never rotates. It stays in the position you were painting. Thus, if you rotate your iPad upside down, your painting will be upside down, but the controls will be right side up. This mimics a traditional canvas.

      However, many of the Effects in Pena are orientation aware and will render differently (or the same) based on the orientation of the device and the particular Effect being used.


      Using Panes

      Pena organizes its controls in a variety of Panes. For example, the primary Pane in Pena is the Control Pane and is visible as soon as you launch Pena:

      The Panes float over the Canvas. You can change the location of the Control Pane by using the up/down arrow on the left or right side of the Control Pane. Tap, hold, and drag the arrow to reposition the Pane anywhere over the Canvas.

      When you want to paint, just start painting on the Canvas and all Panes will hide. When you lift your finger after painting the Panes will reappear. (As you will discover later, there are other ways to view the entire Canvas before you start painting.)

      Most of the icons on the Control Pane will open other Panes. These Panes will attach either to the top or bottom of the Control Pane and will move with the Control Pane if you move it.

      In most cases, to dismiss a sub-Pane you can tap the button that brought up the original Pane. There is an exception to this... a series of Panes called Options Panes can be dismissed by tapping anywhere, including the Canvas.

      You can also control how Panes are closed in Preferences.


      How Painting Works

      The following diagram gives an overview of how painting in Pena works:

      1. Color 1 and Color 2 - All paint starts with two colors defined, Color 1 and Color 2. Color 1 is the Primary Color and Color 2 is an additional color to use in various Effects. Colors are set in the Color Picker.
      2. 0-32 Brush Effects - Color 1 and Color 2 are handed to the Brush Effects. You can have up to 32 Brush Effects in current use. If no Brush Effects are used, Color 1 is what will end up being painted with. Otherwise the Brush Effects will modify Color 1 and Color 2 dynamically to produce the actual paint.
      3. 0-32 Surface Effects - The Surface can also contain Effects that make up the Intelligent Canvas. If no Surface Effects are defined the Color 1 as modified by any Brush Effects will be used, otherwise the Surface Effects will either modify or override Color 1 and Color 2 to produce the actual paint.
      4. Final Drawing Surface - The Drawing Surface is the final destination for the paint. This is your Canvas and your final painting. The Drawing Surface can also be used as a Texture in Brush and Surface Effects, allowing you to use the existing painting as input for the next layer of paint.
      5. Back Light - Behind the canvas is a Back Light. By default it is black, but you can change the color at any time in the Preferences Pane. The Back Light shines through anywhere you have not yet laid paint. It can also shine through partially transparent paint.

      Note that there is a setting in the Preferences Pane that lets you switch the order of Step 2 (The Brush Effects) and Step 3 (The Surface Effects) in the above diagram. By default Brush Effects execute before Surface Effects, however, when the setting is changed Surface Effects execute first, then Brush Effects.

      What exactly are Brush and Surface Effects? Technically these are openGL shaders. Artistically these are Effects that will modify paint. Some of the Effects will completely override Color 1 and Color 2, creating their own unique colors. Other Effects will use Color 1 and Color 2 to modify the paint in some way. As the Colors are passed from Effect to Effect, each modifies the previous color in some fashion to produce the final color.

      This is explained in more detail in the Effects Pane and the Shader Library section of the manual, but below are two simple examples of how programs are used to paint:

      Example #1... Tinted Magnolia

      This example shows two simple Brush Effects being used together. First, we set Color 2 to a nice blue color. Then, we set Brush Effect #1 to Texture and loaded a photo of a Magnolia flower (we also put the photo onto the Canvas). We then set Brush Effect #2 to take the Hue from Color 2 and use it to Tint where we paint.

      We painted a couple of the flower petals and the result is a blush tint applied.

      Example #2... Psychedelic Magnolia

      This example shows three simple Brush Effects being used together. This example completely ignores the original Color 1 and Color 2. Our Brush Effect #1 is our Magnolia Photo (Texture) and outputs Color 1. We then set Brush Effect #2 to a Four-Color Gradient, with Red, Green, Blue, and White corners to output Color 2. Finally we set Brush Effect #3 to a Color Difference between Color 2 and Color 1.

      The effect has been applied to the entire texture in this photo.


      A Complete Effects List

      Brush and Surface Effects share from the same list of Effects. All Effects can be used for both Brushes and Surfaces.

      Below is a complete list of all Effects in Pena, by Category. Tap the Effect for more detailed information and examples.

      Category: Color Source Effects

      Category: Procedural Source Effects

      Category: Color Filter Effects

        AverageAverage Color 1 with Color 2
        BlendA weighted average of Color 1 with Color 2
        BrightnessAdjust the brightness of Color 1 or Color 2
        ContrastAdjust contrast/brightness of Color 1 or 2
        DesaturateSimple % desaturation of Color 1 Color 2
        Exchange ChannelsExchange Channels within Color 1 or Color 2
        InvertInverts Color 1 or Color 2
        MaximumProduce the maximum of Color 1 or Color 2
        MinimumProduce the minimum of Color 1 with Color 2
        SaturationAdjust the saturation of Color 1 or Color 2
        SwapSwap components between Color 1 and Color 2
        Tint (Modify HSB)Trade HSB components between Color 1 and Color 2
        Transparency (Alpha)Adjust Color 1 or Color 2 Alpha based on ranges

      Category: Spatial Filter Effects

      Category: Math and Logic Effects

      Category: Special Effects


      Example Effect Program

      The result we want to achieve is a colorful weave pattern of horizontal and vertical stripes.

      To give an example how Effects are put together to create a more complex paint Effects we give a short example that combines 10 Effects into one complex brush.

      We begin by presenting the entire program. The following represents what is in our first 10 Brush Effect Slots:

      1. 2-Color Gradient, with default values
      2. Stripes, Vertical, with Output Color 1 set to Ignore and Output Color 2 set to Replace
      3. Color Difference, with default values
      4. Color Save, with default values
      5. Color, with default values
      6. 4-Color Gradient, with default values
      7. Stripes, Horizontal, with Output Color 1 set to Ignore and Output Color 2 set to Replace
      8. Color Difference, with default values
      9. Color Restore, with Restore Tmp 1 to 2 turn on, and all other options turned off
      10. Color Difference, with default values

      Remember, the output from each Effect is fed into the input of the next Effect. That means the output of Slot 1 is fed to the input of Slot 2, Slot 2 to Slot 3, etc, until the final Slot 10, where the output of it is drawn to the Canvas.

      Now lets go through the above Effects and see what they produced.

      Slot 1 and Slot 2 give us a 2-Color Gradient in Color 1 and a Stripes, Vertical in Color 2:

      Slot 3 applies a Color Difference between Color 1 and Color 2 and outputs the result to Color 1, giving us this:

      Slot 4 has a Color Save and we save Color 1 to a temporary color.

      Slot 5 has a Color Effect with default values which resets Color 1 to white and Color 2 to black (we do this for the Strips, Horizontal that comes up).

      Slot 6 and Slot 7 give us a 4-Color Gradient in Color 1 and a Stripes, Horizontal in Color 2:

      Slot 8 applies a Color Difference between Color 1 and Color 2 and outputs the result to Color 1, giving us this:

      We now have a new result in Color 1.

      Slot 9 applies a Color Restore with all options turned off except for Restore Tmp 1 to 2. This forces the temporary Color 1 to be restored to Color 2.

      Finally, Slot 10 applies a Color Difference between Color 1 and Color 2 and outputs our final result:

      We have shown, above each step of the process and what it would take as input and provide as output. However, this all happens instantly when you paint. All the steps above are executed, in order, but you only see the final image as the result.


      Online Video Tutorials

      If you would prefer to view Video Tutorials instead of reading the complete manual, we have prepared the following tutorial sessions.

      These will display in a new window.

      For best viewing set the YouTube video quality to 720p(hd).


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    pena © 2014 by David Cook
    Apple®, the Apple logo, iPad, iPad Air, iPad Mini, iPod, iPhone, and iTunes
    are trademarks of Apple Inc., registered in the U.S. and other countries.
    Wacom®, and Wacom Intuos Creative Stylus are trademarks of Wacom, registered in the U.S and other countries.