In my project I am creating Vertexes programmatically which means I am filling
following struct with data I am creating in application.
struct Vertex{
var position: SIMD3<Float>
var color: SIMD4<Float>
var textCoors: SIMD2<Float>
}
My objects are simple they are planes consist of two triangles.
I am creating texture coordinates with following code;
pI is the plane index. My object consists of certain number of planes.
l is the index of corner positions of planes.
It works fine if my planes are square or rectangle it places texture seamlessly.
But if my quadrilateral corner coordinates are not symmetrical.
(Square and rectangle is special case of quadrilateral)
Texture is deforming.
I could not find fine solution I have some ideas like making may plane with many
small squares but it feels crappy There should be better solution.
func textureRip(pI: Int, l: Int, vertex: [[SIMD3<Float>]]) -> SIMD2<Float> {
var textCoor0 = SIMD2<Float>()
// We have this ratio because metalview coordinate system 2x2 unit size
// from -1 to 1 for both x and y. Texture coordinate sistem is 1 unit wide and
// unit height. (0 to 1). So metal view twice as much bigger.
let ratio:Float = 2
// We are adding 1 to metal view values because its values begins
// from -1 so we are shifting its coordinate system to texture coordinate
// system along wiht ratio.
let x0 = (vertex[pI][0].x + 1) / ratio
let x = (vertex[pI][1].x + 1) / ratio
// We are using "1 -" because texture coordinate sistem origin is
// at the top left corner and metal view coordinate system at lower left corner
// in that case texture look upside down so we are turning it using "1-".
let y0 = 1 - (vertex[pI][0].y + 1) / ratio
let y = 1 - (vertex[pI][2].y + 1) / ratio
if l == 0 {
textCoor0 = SIMD2<Float>( x0 , y0)
} else if l == 1 {
textCoor0 = SIMD2<Float>( x , y0)
} else if l == 2 {
textCoor0 = SIMD2<Float>( x , y)
} else {
textCoor0 = SIMD2<Float>( x0 , y)
}
return textCoor0
}
