Weird Color Artifacts when trying to use Ping-Pong Framebuffers
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I am trying to write a shader for a multi step effect with ping-pong buffers using Java and Lwjgl. But it looks different from how it looks in ShaderToy. So in my searches for an answer, I stripped everything down to a much simpler shader which is basically just this:
glFragColor = texture2D(u_Texture, v_TexCoords) * 3.0;
I am multiplying the texture color for a 512x512 image, using ping-pong buffers of 512x512. When I run this 3 steps, this is the output:
Top left is the original image, all pixels are completely black except white and yellow ones. Steps go clockwise to bottom left. As you can see some artifacts are creeping in, at first I thought it could be normal but this does not happen with the same shader in ShaderToy. If I do not multiply the color everything is ok and I get the same image out no matter how many ping-pongs. If I sample with a few pixels offset every step, image is displaced correctly to the sum of all steps without a problem (So I think the texture coordinates are not wrong).
I know I should have shared code but FrameBuffer allocations, Quad setup, shaders etc. are all spanning several source files and it would not be practical. I am sort of new at this, and just hoping this is common enough of a pitfall/setup problem that some experienced people can guess what may be going on by looking at the image.
opengl glsl
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
add a comment |
I am trying to write a shader for a multi step effect with ping-pong buffers using Java and Lwjgl. But it looks different from how it looks in ShaderToy. So in my searches for an answer, I stripped everything down to a much simpler shader which is basically just this:
glFragColor = texture2D(u_Texture, v_TexCoords) * 3.0;
I am multiplying the texture color for a 512x512 image, using ping-pong buffers of 512x512. When I run this 3 steps, this is the output:
Top left is the original image, all pixels are completely black except white and yellow ones. Steps go clockwise to bottom left. As you can see some artifacts are creeping in, at first I thought it could be normal but this does not happen with the same shader in ShaderToy. If I do not multiply the color everything is ok and I get the same image out no matter how many ping-pongs. If I sample with a few pixels offset every step, image is displaced correctly to the sum of all steps without a problem (So I think the texture coordinates are not wrong).
I know I should have shared code but FrameBuffer allocations, Quad setup, shaders etc. are all spanning several source files and it would not be practical. I am sort of new at this, and just hoping this is common enough of a pitfall/setup problem that some experienced people can guess what may be going on by looking at the image.
opengl glsl
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
3
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26
add a comment |
I am trying to write a shader for a multi step effect with ping-pong buffers using Java and Lwjgl. But it looks different from how it looks in ShaderToy. So in my searches for an answer, I stripped everything down to a much simpler shader which is basically just this:
glFragColor = texture2D(u_Texture, v_TexCoords) * 3.0;
I am multiplying the texture color for a 512x512 image, using ping-pong buffers of 512x512. When I run this 3 steps, this is the output:
Top left is the original image, all pixels are completely black except white and yellow ones. Steps go clockwise to bottom left. As you can see some artifacts are creeping in, at first I thought it could be normal but this does not happen with the same shader in ShaderToy. If I do not multiply the color everything is ok and I get the same image out no matter how many ping-pongs. If I sample with a few pixels offset every step, image is displaced correctly to the sum of all steps without a problem (So I think the texture coordinates are not wrong).
I know I should have shared code but FrameBuffer allocations, Quad setup, shaders etc. are all spanning several source files and it would not be practical. I am sort of new at this, and just hoping this is common enough of a pitfall/setup problem that some experienced people can guess what may be going on by looking at the image.
opengl glsl
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
I am trying to write a shader for a multi step effect with ping-pong buffers using Java and Lwjgl. But it looks different from how it looks in ShaderToy. So in my searches for an answer, I stripped everything down to a much simpler shader which is basically just this:
glFragColor = texture2D(u_Texture, v_TexCoords) * 3.0;
I am multiplying the texture color for a 512x512 image, using ping-pong buffers of 512x512. When I run this 3 steps, this is the output:
Top left is the original image, all pixels are completely black except white and yellow ones. Steps go clockwise to bottom left. As you can see some artifacts are creeping in, at first I thought it could be normal but this does not happen with the same shader in ShaderToy. If I do not multiply the color everything is ok and I get the same image out no matter how many ping-pongs. If I sample with a few pixels offset every step, image is displaced correctly to the sum of all steps without a problem (So I think the texture coordinates are not wrong).
I know I should have shared code but FrameBuffer allocations, Quad setup, shaders etc. are all spanning several source files and it would not be practical. I am sort of new at this, and just hoping this is common enough of a pitfall/setup problem that some experienced people can guess what may be going on by looking at the image.
opengl glsl
opengl glsl
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
edited Nov 26 '18 at 20:06
Rabbid76
43.8k123354
43.8k123354
asked Nov 26 '18 at 19:35
sydnalsydnal
708
asked Nov 26 '18 at 19:35
sydnalsydnal
708
asked Nov 26 '18 at 19:35
sydnalsydnal
708
708
3
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26
add a comment |
3
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26
3
3
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26
add a comment |
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3
Magic here is rare. WIth code you post, things get much more "guesseable"
– Ripi2
Nov 26 '18 at 20:12
Are you multiplying the values of the texture to the same texture? And that in a kind of loop? If so, maybe the initial value is 1 of 255 and the error is increasing over time...
– Thomas
Nov 26 '18 at 20:13
@Thomas no; I am drawing it onto a new Frame buffer with its own texture attachment, and I am clearing it to black before drawing.
– sydnal
Nov 27 '18 at 8:40
@Ripi2 I guess I should. I will try to port it over to webgl and arrange the main logic as a single source file that can be reasoned with. Thanks.
– sydnal
Nov 27 '18 at 18:55
@Ripi2 I have now ported the whole thing over to WebGL and opened a new topic here: link. It was the actual problem that I was trying to solve when I opened this question.
– sydnal
Dec 2 '18 at 11:26