Create OpenGL shapes and apply transformations using finger gestures

Kotlin Library used for detecting finger gestures and applying there corresponding transformation to a 3x3 Matrix that is then converted in to a FloatArray that hold values for the 4x4 OpenGL matrix. That way you can apply the following transformations: scale, translation and rotation to the matrix and then use it to apply the transformations to OpenGL shapes.

Supported OpenGL shapes are:

• Circle
• Ellipse
• Image
• Line
• PassByCurve
• IrregularPolygon
• Rectangle
• RegularPolygon
• Triangle

Add the jitpack maven repository

allprojects {
  repositories {
    ...
    maven { url 'https://jitpack.io' }
  }
}

Add the dependency

dependencies {
  implementation 'com.github.slaviboy:OpenGL:v0.2.0'
}

Adding shapes is easy, the code below is example of creating a OpenGL rectangle. To learn more on how to implement your own OpenGL view and draw the shapes you can read the official wiki page here.

// gesture detector used for applying transformations to all OpenGL objects: line, images, triangles..
val mainGestureDetector: OpenGLMatrixGestureDetector = OpenGLMatrixGestureDetector()

// create program for shapes that use the same colors
val singleColorsProgram = OpenGLStatic.setSingleColorsProgram()

// create single rectangle
val rectangle = Rectangle(
     x = 300f,
     y = 200f,
     width = 300f,
     height = 150f,
     color = Color.BLACK,
     strokeWidth = 5f,
     gestureDetector = mainGestureDetector,
     preloadProgram = singleColorsProgram,
     style = Shapes.STYLE_FILL
)