CODEWITHSUNDEEP
ios
Johan Andersson
Johan Andersson

Reputation: 151

"warping" an image on iOS

I'm trying to find a way to do something similar to this on iOS:

enter image description here

Does anyone know a simple way to do it?

Upvotes: 1

Views: 825

Answers (1)

Sam
Sam

Reputation: 7858

I don't know of a oneliner to do this, but you can use OpenGL to render a textured grid with quads, which has the texture coordinates equally distributed.

Exampe of 2x2 grid:

{0.0,1.0}        {0.33333,1.0}        {1.0,1.0}


{0.0,0.33333}    {0.33333,0.33333}    {1.0,0.33333}


{0.0,0.0}        {0.33333,0.0}        {1.0,0.0}

If you move shared vertices of adjacent quads (like in your example) while texture coords remain, you get a warp effect. You need a trivial vertex and fragment shader when using OpenGL ES, especially if you want to smoothen the warp effect, which is linearly interpolated per quad/triangle in its simple form.

Upvotes: 1

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