How to draw transparent background in webGL on canvas
https://codepen.io/anon/pen/zMRjwv
In that page, I want to draw a transparent background but it's not working when I use gl.clearColor(0, 0, 0, 0).
const gl = canvas.getContext('webgl', {alpha: false});
Set alpha:false is also can't because 2D context
attributes: alpha: Boolean that indicates if the canvas contains an alpha channel.
If set to false, the browser will knows that the backdrop is always opaque, which can speed up drawing of transparent content and images.WebGL context.
attributes:
alpha: Boolean that indicates if the canvas contains an alpha buffer.
css webgl shader
edited Nov 22 '18 at 16:05
Skynet
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
|
show 1 more comment
https://codepen.io/anon/pen/zMRjwv
In that page, I want to draw a transparent background but it's not working when I use gl.clearColor(0, 0, 0, 0).
const gl = canvas.getContext('webgl', {alpha: false});
Set alpha:false is also can't because 2D context
attributes: alpha: Boolean that indicates if the canvas contains an alpha channel.
If set to false, the browser will knows that the backdrop is always opaque, which can speed up drawing of transparent content and images.WebGL context.
attributes:
alpha: Boolean that indicates if the canvas contains an alpha buffer.
css webgl shader
edited Nov 22 '18 at 16:05
Skynet
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
1
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
1
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05
|
show 1 more comment
https://codepen.io/anon/pen/zMRjwv
In that page, I want to draw a transparent background but it's not working when I use gl.clearColor(0, 0, 0, 0).
const gl = canvas.getContext('webgl', {alpha: false});
Set alpha:false is also can't because 2D context
attributes: alpha: Boolean that indicates if the canvas contains an alpha channel.
If set to false, the browser will knows that the backdrop is always opaque, which can speed up drawing of transparent content and images.WebGL context.
attributes:
alpha: Boolean that indicates if the canvas contains an alpha buffer.
css webgl shader
edited Nov 22 '18 at 16:05
Skynet
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
https://codepen.io/anon/pen/zMRjwv
In that page, I want to draw a transparent background but it's not working when I use gl.clearColor(0, 0, 0, 0).
const gl = canvas.getContext('webgl', {alpha: false});
Set alpha:false is also can't because 2D context
attributes: alpha: Boolean that indicates if the canvas contains an alpha channel.
If set to false, the browser will knows that the backdrop is always opaque, which can speed up drawing of transparent content and images.WebGL context.
attributes:
alpha: Boolean that indicates if the canvas contains an alpha buffer.
css webgl shader
css webgl shader
edited Nov 22 '18 at 16:05
Skynet
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
edited Nov 22 '18 at 16:05
Skynet
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
edited Nov 22 '18 at 16:05
Skynet
4,32452640
edited Nov 22 '18 at 16:05
Skynet
4,32452640
edited Nov 22 '18 at 16:05
Skynet
4,32452640
4,32452640
asked Nov 22 '18 at 2:05
包青天包青天
32
asked Nov 22 '18 at 2:05
包青天包青天
32
asked Nov 22 '18 at 2:05
包青天包青天
32
32
1
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
1
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05
|
show 1 more comment
1
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
1
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05
1
1
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
1
1
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05
|
show 1 more comment
1 Answer
1
active
oldest
votes
The issue with the sample you linked to is that the sample itself is not transparent. It draw a background, then it draws sakura petals, then it applies a glow shader to give the petals a glow. This generates an opaque image so setting the canvas alpha to true (or not setting it all) won't make a difference.
To make it transparent comment out the following lines and change the background color
// gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
// gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// renderBackground();
renderPointFlowers();
// renderPostProcess();
You can then possibly adjust the petal brightness changing this line
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
to this for example
col *= mix(1.8, 3.0, pow(abs(coord.x), 0.3));
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
add a comment |
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1 Answer
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oldest
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The issue with the sample you linked to is that the sample itself is not transparent. It draw a background, then it draws sakura petals, then it applies a glow shader to give the petals a glow. This generates an opaque image so setting the canvas alpha to true (or not setting it all) won't make a difference.
To make it transparent comment out the following lines and change the background color
// gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
// gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// renderBackground();
renderPointFlowers();
// renderPostProcess();
You can then possibly adjust the petal brightness changing this line
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
to this for example
col *= mix(1.8, 3.0, pow(abs(coord.x), 0.3));
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
add a comment |
The issue with the sample you linked to is that the sample itself is not transparent. It draw a background, then it draws sakura petals, then it applies a glow shader to give the petals a glow. This generates an opaque image so setting the canvas alpha to true (or not setting it all) won't make a difference.
To make it transparent comment out the following lines and change the background color
// gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
// gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// renderBackground();
renderPointFlowers();
// renderPostProcess();
You can then possibly adjust the petal brightness changing this line
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
to this for example
col *= mix(1.8, 3.0, pow(abs(coord.x), 0.3));
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
add a comment |
The issue with the sample you linked to is that the sample itself is not transparent. It draw a background, then it draws sakura petals, then it applies a glow shader to give the petals a glow. This generates an opaque image so setting the canvas alpha to true (or not setting it all) won't make a difference.
To make it transparent comment out the following lines and change the background color
// gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
// gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// renderBackground();
renderPointFlowers();
// renderPostProcess();
You can then possibly adjust the petal brightness changing this line
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
to this for example
col *= mix(1.8, 3.0, pow(abs(coord.x), 0.3));
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
The issue with the sample you linked to is that the sample itself is not transparent. It draw a background, then it draws sakura petals, then it applies a glow shader to give the petals a glow. This generates an opaque image so setting the canvas alpha to true (or not setting it all) won't make a difference.
To make it transparent comment out the following lines and change the background color
// gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
// gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// renderBackground();
renderPointFlowers();
// renderPostProcess();
You can then possibly adjust the petal brightness changing this line
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
to this for example
col *= mix(1.8, 3.0, pow(abs(coord.x), 0.3));
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
edited Nov 22 '18 at 9:14
Temani Afif
67.7k93776
67.7k93776
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
answered Nov 22 '18 at 7:22
gmangman
46.7k17111200
46.7k17111200
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
add a comment |
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
Problem solved.Thank you very much.And apologize for my actions.I asked for an example of nearly a 1000 lines of code.I'm so sorry and grateful.
– 包青天
Nov 22 '18 at 7:30
add a comment |
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1
Tried to make sense of the original question and improve it.
– Nic3500
Nov 22 '18 at 3:40
1
I'm sorry but 1,000 lines of code are not a Minimal, Complete, and Verifiable example
– Alon Eitan
Nov 22 '18 at 5:56
I'm sorry I just want to draw transparent background or 2d imge in webgl 3D.
– 包青天
Nov 22 '18 at 6:02
A lot of answers tell me set gl.clearColor(0, 0, 0, 0). const gl = canvas.getContext('webgl', {alpha: false});But that's wrong.
– 包青天
Nov 22 '18 at 6:04
You can't have a transparent background with alpha:false.. Alpha:false = 100% opaque period.
– gman
Nov 22 '18 at 6:05