Retrieving occluded faces given a rectangular region
I am trying to do a click-and-drag selection to select all the visible faces of a model (similar to those in 3D modelling software such as Blender).
Initially I am thinking of using line intersection to find all the occluded faces in the scene: for every pixel in the viewport, trace a line into the scene and find the first intersection. Then the list of occluded faces would be the ones that did not get intersected. But then after experimentation I realized that this method is very slow.
I heard of another method which goes something like:
- Assigning a unique color for each primitive.
- Project all those onto a virtual plane coincides with the viewport
- From the projected pixels, if the colors corresponding to a primitive are not present, then it is occluded.
The problem is that I have no idea how to go about creating such a "virtual" plane, and at the same time not revealing it to the end-user. Any help or better idea to solve this?
opengl
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
add a comment |
I am trying to do a click-and-drag selection to select all the visible faces of a model (similar to those in 3D modelling software such as Blender).
Initially I am thinking of using line intersection to find all the occluded faces in the scene: for every pixel in the viewport, trace a line into the scene and find the first intersection. Then the list of occluded faces would be the ones that did not get intersected. But then after experimentation I realized that this method is very slow.
I heard of another method which goes something like:
- Assigning a unique color for each primitive.
- Project all those onto a virtual plane coincides with the viewport
- From the projected pixels, if the colors corresponding to a primitive are not present, then it is occluded.
The problem is that I have no idea how to go about creating such a "virtual" plane, and at the same time not revealing it to the end-user. Any help or better idea to solve this?
opengl
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32
add a comment |
I am trying to do a click-and-drag selection to select all the visible faces of a model (similar to those in 3D modelling software such as Blender).
Initially I am thinking of using line intersection to find all the occluded faces in the scene: for every pixel in the viewport, trace a line into the scene and find the first intersection. Then the list of occluded faces would be the ones that did not get intersected. But then after experimentation I realized that this method is very slow.
I heard of another method which goes something like:
- Assigning a unique color for each primitive.
- Project all those onto a virtual plane coincides with the viewport
- From the projected pixels, if the colors corresponding to a primitive are not present, then it is occluded.
The problem is that I have no idea how to go about creating such a "virtual" plane, and at the same time not revealing it to the end-user. Any help or better idea to solve this?
opengl
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
I am trying to do a click-and-drag selection to select all the visible faces of a model (similar to those in 3D modelling software such as Blender).
Initially I am thinking of using line intersection to find all the occluded faces in the scene: for every pixel in the viewport, trace a line into the scene and find the first intersection. Then the list of occluded faces would be the ones that did not get intersected. But then after experimentation I realized that this method is very slow.
I heard of another method which goes something like:
- Assigning a unique color for each primitive.
- Project all those onto a virtual plane coincides with the viewport
- From the projected pixels, if the colors corresponding to a primitive are not present, then it is occluded.
The problem is that I have no idea how to go about creating such a "virtual" plane, and at the same time not revealing it to the end-user. Any help or better idea to solve this?
opengl
opengl
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
edited Nov 16 '18 at 14:42
genpfault
42.5k954100
42.5k954100
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
asked Nov 16 '18 at 5:07
John TanJohn Tan
587617
587617
the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32
add a comment |
the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32
the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32
add a comment |
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the term to search for is "framebuffer"
– kmdreko
Nov 16 '18 at 5:32
Search for OpenGL picking hack
– Nadir
Nov 16 '18 at 10:32