<p>I have somewhat generalized version of this question: <a href="https://stackoverflow.com/questions/52475104/how-to-show-visible-part-of-planar-world-rendered-with-3d-perspective-on-topside">https://stackoverflow.com/questions/52475104/how-to-show-visible-part-of-planar-world-rendered-with-3d-perspective-on-topside</a> -‎ I would also like to know which part(s) of a given plane (not necessarily infinite) is visible to the camera, but I would like the solution to also consider objects in front of the plane that may be obstructing it's visibility.</p>

<p>Since that may be very hard problem to solve analyticaly (if at all in OpenGL) I would be happy also with solution based on "rasterisation". The problem would then be restated as: How to map rendered pixels of a plane back to it's 3D representation. Or in other (maybe too naive) words - how to transform rendered visible area of a plane to it's texture.</p>

<p>I'm a beginner in computer graphics so I would be glad even for pointing out the right study materials.</p>

CC BY-SA 4.0
2018-10-24T07:59:54.837Z
What do you mean with part(s)? Like closed patches within a plane that are visible from the camera?
Nadir
CC BY-SA 4.0
2018-10-25T08:06:24.923Z
Yes, that's it. I have meanwhile realized that it may be a dumb question because it's in fact a complementary problem of shadow mapping.
calavera.info
CC BY-SA 4.0
2018-10-25T08:33:55.067Z
I would make it simpler than shadow mapping, more close the the picking hack. I would render g-buffers for whatever info is needed of (color/pos/depth/etc.), and adding an extra render target where you would control what to render by using a uniform color for each element (using black for those you are not interested in, for example).
Nadir
<opengl>
Identification of visible area of a plane in OpenGL
calavera.info
# Identification of visible area of a plane in OpenGL

(Asked by: username_0 on 2018-10-23)

I have somewhat generalized version of this question: <https://stackoverflow.com/questions/52475104/how-to-show-visible-part-of-planar-world-rendered-with-3d-perspective-on-topside> -‎ I would also like to know which part(s) of a given plane (not necessarily infinite) is visible to the camera, but I would like the solution to also consider objects in front of the plane that may be obstructing it's visibility.

Since that may be very hard problem to solve analyticaly (if at all in OpenGL) I would be happy also with solution based on "rasterisation". The problem would then be restated as: How to map rendered pixels of a plane back to it's 3D representation. Or in other (maybe too naive) words - how to transform rendered visible area of a plane to it's texture.

I'm a beginner in computer graphics so I would be glad even for pointing out the right study materials.

**Tags:** opengl

> **Comments:**
> **username_1**: What do you mean with part(s)? Like closed patches within a plane that are visible from the camera?  
> **username_0**: Yes, that's it. I have meanwhile realized that it may be a dumb question because it's in fact a complementary problem of shadow mapping.  
> **username_1**: I would make it simpler than shadow mapping, more close the the picking hack. I would render g-buffers for whatever info is needed of (color/pos/depth/etc.), and adding an extra render target where you would control what to render by using a uniform color for each element (using black for those you are not interested in, for example).  

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## 0 answers

