How to see the generated edges after tessellation?
I am trying to see how my mesh is being transformed by the tessellation shader. I have seen multiple images of this online so i know it is possible.
Reading the khronos wiki it seems that to generate the same behaviour as GL_LINES I should set the patch vertices to 2 like this:
glPatchParameteri(GL_PATCH_VERTICES, 2)
However this results in the exact same output as
glPatchParameteri(GL_PATCH_VERTICES, 3)
In other words, I am seeing filled triangles instead of lines. I am drawing using GL_PATCHES and I am not getting compilation nor runtime errors.
How can I see the generated edges?
c++ graphics opengl-es glsl tessellation
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
add a comment |
I am trying to see how my mesh is being transformed by the tessellation shader. I have seen multiple images of this online so i know it is possible.
Reading the khronos wiki it seems that to generate the same behaviour as GL_LINES I should set the patch vertices to 2 like this:
glPatchParameteri(GL_PATCH_VERTICES, 2)
However this results in the exact same output as
glPatchParameteri(GL_PATCH_VERTICES, 3)
In other words, I am seeing filled triangles instead of lines. I am drawing using GL_PATCHES and I am not getting compilation nor runtime errors.
How can I see the generated edges?
c++ graphics opengl-es glsl tessellation
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
add a comment |
I am trying to see how my mesh is being transformed by the tessellation shader. I have seen multiple images of this online so i know it is possible.
Reading the khronos wiki it seems that to generate the same behaviour as GL_LINES I should set the patch vertices to 2 like this:
glPatchParameteri(GL_PATCH_VERTICES, 2)
However this results in the exact same output as
glPatchParameteri(GL_PATCH_VERTICES, 3)
In other words, I am seeing filled triangles instead of lines. I am drawing using GL_PATCHES and I am not getting compilation nor runtime errors.
How can I see the generated edges?
c++ graphics opengl-es glsl tessellation
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
I am trying to see how my mesh is being transformed by the tessellation shader. I have seen multiple images of this online so i know it is possible.
Reading the khronos wiki it seems that to generate the same behaviour as GL_LINES I should set the patch vertices to 2 like this:
glPatchParameteri(GL_PATCH_VERTICES, 2)
However this results in the exact same output as
glPatchParameteri(GL_PATCH_VERTICES, 3)
In other words, I am seeing filled triangles instead of lines. I am drawing using GL_PATCHES and I am not getting compilation nor runtime errors.
How can I see the generated edges?
c++ graphics opengl-es glsl tessellation
c++ graphics opengl-es glsl tessellation
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
edited Nov 15 '18 at 21:10
genpfault
42.5k954100
42.5k954100
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
asked Nov 15 '18 at 16:08
MakoganMakogan
1,8581830
1,8581830
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
If you cannot use the polygon mode, you can employ the geometry shader. The geometry shader is a stage that is executed after tessellation. So, you can have a geometry shader that takes a triangle as input and produces a line strip of three lines as output. This will show the wireframe. It will also draw inner edges twice, though.
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
add a comment |
Just use glPolygonMode( GL_FRONT_AND_BACK, GL_LINE ); in your initialization code. Also you can call this based on some key so that you can toggle between wireframe and polygon mode.
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
add a comment |
I would like to point out that this question represents a stark misunderstanding of how Tessellation works.
The number of vertices in a patch is irrelevant to "how my mesh is being transformed by the tessellation shader".
Tessellation is based on an abstract patch. That is, if your TES uses triangles as its abstract patch type, then it will generate triangles. This is just as true whether your vertices-per-patch count is 20 or 2.
The job of the code in the TES is to figure out how to apply the tessellation of the abstract patch to the vertex data of the patch in order to produce the actual tessellated output vertex data.
So if you're tessellating a triangle, your TES gets a 3-element barycentric coordinate (gl_TessCoord) that determines the location in the abstract triangle to generate the vertex data for. The tessellation primitive generator's job is to decide which vertices to generate and how to assemble them into primitives (triangle edge connectivity).
So basically, the number of patch vertices is irrelevant to the edge connectivity graph. The only thing that matters for that is the abstract patch type and the tessellation levels being applied to it.
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
If you cannot use the polygon mode, you can employ the geometry shader. The geometry shader is a stage that is executed after tessellation. So, you can have a geometry shader that takes a triangle as input and produces a line strip of three lines as output. This will show the wireframe. It will also draw inner edges twice, though.
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
add a comment |
If you cannot use the polygon mode, you can employ the geometry shader. The geometry shader is a stage that is executed after tessellation. So, you can have a geometry shader that takes a triangle as input and produces a line strip of three lines as output. This will show the wireframe. It will also draw inner edges twice, though.
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
add a comment |
If you cannot use the polygon mode, you can employ the geometry shader. The geometry shader is a stage that is executed after tessellation. So, you can have a geometry shader that takes a triangle as input and produces a line strip of three lines as output. This will show the wireframe. It will also draw inner edges twice, though.
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
If you cannot use the polygon mode, you can employ the geometry shader. The geometry shader is a stage that is executed after tessellation. So, you can have a geometry shader that takes a triangle as input and produces a line strip of three lines as output. This will show the wireframe. It will also draw inner edges twice, though.
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
answered Nov 15 '18 at 17:06
Nico SchertlerNico Schertler
25.6k42450
25.6k42450
add a comment |
add a comment |
Just use glPolygonMode( GL_FRONT_AND_BACK, GL_LINE ); in your initialization code. Also you can call this based on some key so that you can toggle between wireframe and polygon mode.
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
add a comment |
Just use glPolygonMode( GL_FRONT_AND_BACK, GL_LINE ); in your initialization code. Also you can call this based on some key so that you can toggle between wireframe and polygon mode.
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
add a comment |
Just use glPolygonMode( GL_FRONT_AND_BACK, GL_LINE ); in your initialization code. Also you can call this based on some key so that you can toggle between wireframe and polygon mode.
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
Just use glPolygonMode( GL_FRONT_AND_BACK, GL_LINE ); in your initialization code. Also you can call this based on some key so that you can toggle between wireframe and polygon mode.
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
answered Nov 15 '18 at 16:14
Paritosh KulkarniParitosh Kulkarni
603413
603413
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
add a comment |
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
This is probably the right answer for the actual question, but I am on OpenGL ES 3.2 so I cannot change the polygon mode, any suggestions?
– Makogan
Nov 15 '18 at 16:29
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
That would be little but tricky but doable. Make your drawing two pass . In first pass bind transform feedback.After tessellation stage output your geometry to this transform feedback buffer. Second pass draw the geometry in transform feedback as Line or Line loop or use Geometry shader which comes after tessellation shader take input as triangle/patch and output line as primitve.
– Paritosh Kulkarni
Nov 15 '18 at 17:07
add a comment |
I would like to point out that this question represents a stark misunderstanding of how Tessellation works.
The number of vertices in a patch is irrelevant to "how my mesh is being transformed by the tessellation shader".
Tessellation is based on an abstract patch. That is, if your TES uses triangles as its abstract patch type, then it will generate triangles. This is just as true whether your vertices-per-patch count is 20 or 2.
The job of the code in the TES is to figure out how to apply the tessellation of the abstract patch to the vertex data of the patch in order to produce the actual tessellated output vertex data.
So if you're tessellating a triangle, your TES gets a 3-element barycentric coordinate (gl_TessCoord) that determines the location in the abstract triangle to generate the vertex data for. The tessellation primitive generator's job is to decide which vertices to generate and how to assemble them into primitives (triangle edge connectivity).
So basically, the number of patch vertices is irrelevant to the edge connectivity graph. The only thing that matters for that is the abstract patch type and the tessellation levels being applied to it.
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
add a comment |
I would like to point out that this question represents a stark misunderstanding of how Tessellation works.
The number of vertices in a patch is irrelevant to "how my mesh is being transformed by the tessellation shader".
Tessellation is based on an abstract patch. That is, if your TES uses triangles as its abstract patch type, then it will generate triangles. This is just as true whether your vertices-per-patch count is 20 or 2.
The job of the code in the TES is to figure out how to apply the tessellation of the abstract patch to the vertex data of the patch in order to produce the actual tessellated output vertex data.
So if you're tessellating a triangle, your TES gets a 3-element barycentric coordinate (gl_TessCoord) that determines the location in the abstract triangle to generate the vertex data for. The tessellation primitive generator's job is to decide which vertices to generate and how to assemble them into primitives (triangle edge connectivity).
So basically, the number of patch vertices is irrelevant to the edge connectivity graph. The only thing that matters for that is the abstract patch type and the tessellation levels being applied to it.
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
add a comment |
I would like to point out that this question represents a stark misunderstanding of how Tessellation works.
The number of vertices in a patch is irrelevant to "how my mesh is being transformed by the tessellation shader".
Tessellation is based on an abstract patch. That is, if your TES uses triangles as its abstract patch type, then it will generate triangles. This is just as true whether your vertices-per-patch count is 20 or 2.
The job of the code in the TES is to figure out how to apply the tessellation of the abstract patch to the vertex data of the patch in order to produce the actual tessellated output vertex data.
So if you're tessellating a triangle, your TES gets a 3-element barycentric coordinate (gl_TessCoord) that determines the location in the abstract triangle to generate the vertex data for. The tessellation primitive generator's job is to decide which vertices to generate and how to assemble them into primitives (triangle edge connectivity).
So basically, the number of patch vertices is irrelevant to the edge connectivity graph. The only thing that matters for that is the abstract patch type and the tessellation levels being applied to it.
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
I would like to point out that this question represents a stark misunderstanding of how Tessellation works.
The number of vertices in a patch is irrelevant to "how my mesh is being transformed by the tessellation shader".
Tessellation is based on an abstract patch. That is, if your TES uses triangles as its abstract patch type, then it will generate triangles. This is just as true whether your vertices-per-patch count is 20 or 2.
The job of the code in the TES is to figure out how to apply the tessellation of the abstract patch to the vertex data of the patch in order to produce the actual tessellated output vertex data.
So if you're tessellating a triangle, your TES gets a 3-element barycentric coordinate (gl_TessCoord) that determines the location in the abstract triangle to generate the vertex data for. The tessellation primitive generator's job is to decide which vertices to generate and how to assemble them into primitives (triangle edge connectivity).
So basically, the number of patch vertices is irrelevant to the edge connectivity graph. The only thing that matters for that is the abstract patch type and the tessellation levels being applied to it.
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
answered Nov 15 '18 at 20:59
Nicol BolasNicol Bolas
290k34481655
290k34481655
add a comment |
add a comment |
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