hi i am trying to figure out how to do the following: a video is played using ffmpeg and into a render target (A) four coordinates (Q) describe a polygon inside the render target (A) four other coordinates (E) describe a polygon inside an “output render target” (B) use the Q cords to extract textu…

i have tried to read up on the issue of the texture being warped down the diagonal but the closest i’ve come to a definition of the issue is this stack overflow question: Quad texture stretching on OpenGL - Stack Overflow talking about the interpolation of each of the two triangles in the mesh bein…

this article also talks about the issue, reading it now! :slight_smile: Quadrilateral Interpolation, Part 1 – Nathan Reed’s coding blog Pixels and polygons and shaders, oh my!

this repo is also talking about the “nonaffine” transformations needed to get a proper non-affine quad texture going [image] GitHub - v0idv0id/PerspectiveTexture: This example shows how to render a perspective... This example shows how to render a perspective texture on a quad in…

Very interesting issue :slight_smile: There’s also a part 2: Quadrilateral Interpolation, Part 2 – Nathan Reed’s coding blog Pixels and polygons and shaders, oh my!

I have learned that a cheap way to get around the issue is to have more triangles. The subject is called tesselation. And apparently can be done in a shader

That gave me an idea: orx/orx-shapes at master · openrndr/orx · GitHub has a bezier patch that could be used for this. Unfortunately I discovered issues 350 and 351 . Once they are fixed I think that might be an easy way to map irregular (even curved) shapes. Mmm… would it be enough for you if only …

feels like i’m nearly there. my solution (albeit rookie) is to calculate interpolated points first on the vertical sides of the quad and then from between those calculate and interpolate the horizontal points. i do it twice, once for position and once for texture import org.openrndr.application im…

figured it out :slight_smile: here is the diff gist: https://gist.github.com/sloev/a7492af4ccecf7b99f552da0fff660cc main.kt import org.openrndr.application import org.openrndr.draw.* import org.openrndr.ffmpeg.VideoPlayerConfiguration import org.openrndr.ffmpeg.VideoPlayerFFMPEG import…

Nice!! Congratulations :tada: About performance: if you are not animating the target shape, you can move the quadWriter.write() out of extend so it only calculates the vertexBuffer once (maybe useful if you draw hundreds of such shapes :slight_smile: ) Is this for doing projection mapping with a p…

yup, yeah it only needs to be calculated when either the texture quad or the surface quad changes its cords. yeah i am making a projection mapping vj app for linux: 4 video channels 1 output via udp broadcast to mpv (video player clients) each taking a quadrant of the udp video (think videosplitt…

Video mapping 2d

OPENRNDR How to?

supernihil December 30, 2024, 3:56pm 25

woop woop, your welcome any time

now i have udp broadcast and triangle meshes working too

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Video mapping 2d

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