VSL: Testing an image for an alpha channel
Hi, is it possible to test for the prescence of an alpha channel in a
given image map inside a VSL material?
Something like:
Surface properties
{
do stuff
if (image has alpha)
{
Apply alpha channel of image to surface transparency
}
}
I want to use the same structure of the VSL material for all my
objects to let users simply change the possible parameters that match
the in-game material properties without having to modify the actual
VSL code.
Regards,
Fredrik Bergholtz
Re: Testing an image for an alpha channel
Yes, you can do that, but you're thinking about it wrong. What you want to
do is output to the surface transparency the value held in an images Alpha
channel.
In your Surface Properties shader add a Texture object.
Load your texture with Alpha channel.
Set the output of the texture object (In/Out tab) to Surface:Transparency
In the Bindings tab, click the Edit checkbox and set the bindings so the
Transparency's RG and B channels (destination) are set from the source
image's A channel
At this point I'll mention I can't actually do this because RS's window is
busted and has been as long as I've known the software. When I click Edit
Binding the Source panel extends to below the bottom of the window and I see
no destination panel. No amount of opening and closing windows and panels
and Ctrl left right shift click and dragging will expose the rest of the
interface for me. The way panels auto scale and such I've always found
awkward as they invariably produce a window far longer than my 768 pixel
height display, and often don't terminate at the bottom of the window
anyway.
Anyway, what you are doing is selecting a picture that has Red, Green, Blue
and Alpha components, and saying 'For each pixel, take the images Alpha
value and set that as the transparency value of the Red, Green and Blue
colour components of the surface.' You can just as easily create a black and
white image and set the value of surface transparency to the red component
of the image, using it as a mask.
David Coombes
[EMAIL PROTECTED]
...
- Original Message -
From: [EMAIL PROTECTED]
To: user-list@light.realsoft3d.com
Sent: Saturday, April 29, 2006 11:56 AM
Subject: VSL: Testing an image for an alpha channel
Hi, is it possible to test for the prescence of an alpha channel in a
given image map inside a VSL material?
Something like:
Surface properties
{
do stuff
if (image has alpha)
{
Apply alpha channel of image to surface transparency
}
}
I want to use the same structure of the VSL material for all my
objects to let users simply change the possible parameters that match
the in-game material properties without having to modify the actual
VSL code.
Regards,
Fredrik Bergholtz
Re: Testing an image for an alpha channel
Oh, I think that my description may not have been fully clear. (Bad
pun, sorry :) )
I do all this, the thing is that I want to be able to use the same
material even if the actual image map has no alpha channel. When I try
this, loading an image map with no alpha channel, the bindings get
messed up and the red channel will be sent to transparency. This is
what I want to avoid. Think of it like a special kind of material, I
want to set up a bunch of user editable attributes, one of which is an
image map. If this image map contains an alpha channel, that would be
sent to transparency, but if it doesn't have an alpha channel,
transparency won't be affected by the material.
What I want is to make sure that the last three VSL objects in the
material shown in the attached image are only evaluated if the image
has an alpha channel.
Regards,
Fredrik Bergholtz
On 29/04/06, David Coombes [EMAIL PROTECTED] wrote:
Yes, you can do that, but you're thinking about it wrong. What you want to
do is output to the surface transparency the value held in an images Alpha
channel.
In your Surface Properties shader add a Texture object.
Load your texture with Alpha channel.
Set the output of the texture object (In/Out tab) to Surface:Transparency
In the Bindings tab, click the Edit checkbox and set the bindings so the
Transparency's RG and B channels (destination) are set from the source
image's A channel
At this point I'll mention I can't actually do this because RS's window is
busted and has been as long as I've known the software. When I click Edit
Binding the Source panel extends to below the bottom of the window and I see
no destination panel. No amount of opening and closing windows and panels
and Ctrl left right shift click and dragging will expose the rest of the
interface for me. The way panels auto scale and such I've always found
awkward as they invariably produce a window far longer than my 768 pixel
height display, and often don't terminate at the bottom of the window
anyway.
Anyway, what you are doing is selecting a picture that has Red, Green, Blue
and Alpha components, and saying 'For each pixel, take the images Alpha
value and set that as the transparency value of the Red, Green and Blue
colour components of the surface.' You can just as easily create a black and
white image and set the value of surface transparency to the red component
of the image, using it as a mask.
David Coombes
[EMAIL PROTECTED]
...
- Original Message -
From: [EMAIL PROTECTED]
To: user-list@light.realsoft3d.com
Sent: Saturday, April 29, 2006 11:56 AM
Subject: VSL: Testing an image for an alpha channel
Hi, is it possible to test for the prescence of an alpha channel in a
given image map inside a VSL material?
Something like:
Surface properties
{
do stuff
if (image has alpha)
{
Apply alpha channel of image to surface transparency
}
}
I want to use the same structure of the VSL material for all my
objects to let users simply change the possible parameters that match
the in-game material properties without having to modify the actual
VSL code.
Regards,
Fredrik Bergholtz
vsl.png
Description: PNG image
Re: Testing an image for an alpha channel
Why don't use an image without alpha, instead of no image? Matthias Now, some materials will have an image map set in the image map attribute some will not. The materials that has no image map must still function, i.e. the prescence of an image map must be tested by the code in the vsl material. For materials that do have an image map assigned to the image map attribute of the material the material must test if the image it is currently set to has an alpha channel or not. If it has an alpha channel, these values will be mapped to Surfacs:Transparency with a Texture VSL object. If the image that is currently assigned to the image map property does not have an alpha channel, transparency will not be modified by this material. The thing is that, when the user, or the object loader, assigns an image to the attribute, no changes to the VSL code should be done. Just the value of the attribute should have to be changed. The reason for this material is that I want to have a standard material that has all of the features of the game engine I'm making this stuff for. The key thing is to make sure that the materials used doesn't have any features that are not supported by the game engine. When IU have a VSL material that works, the plan is to encapsulate this material in a new material class defined by my plugin. This class would completely restrict modification of the VSL code. Think of how v3materials are used in RS today. I guess that they too are implemented as regular VSL objects, just that the VSL code is hidden from the users and instad a more simple user interface is presented. Does this help, or am I just making stuff even more complicated? ;) Regards, Fredrik Bergholtz On 29/04/06, Matthias Kappenberg [EMAIL PROTECTED] wrote: Something like this? Matthias - Original Message - Wrom: VZCMHVIBGDADRZFSQH To: user-list@light.realsoft3d.com Sent: Saturday, April 29, 2006 1:59 PM Subject: Re: Testing an image for an alpha channel Oh, I think that my description may not have been fully clear. (Bad pun, sorry :) ) I do all this, the thing is that I want to be able to use the same material even if the actual image map has no alpha channel. When I try this, loading an image map with no alpha channel, the bindings get messed up and the red channel will be sent to transparency. This is what I want to avoid. Think of it like a special kind of material, I want to set up a bunch of user editable attributes, one of which is an image map. If this image map contains an alpha channel, that would be sent to transparency, but if it doesn't have an alpha channel, transparency won't be affected by the material. What I want is to make sure that the last three VSL objects in the material shown in the attached image are only evaluated if the image has an alpha channel. Regards, Fredrik Bergholtz On 29/04/06, David Coombes [EMAIL PROTECTED] wrote: Yes, you can do that, but you're thinking about it wrong. What you want to do is output to the surface transparency the value held in an images Alpha channel. In your Surface Properties shader add a Texture object. Load your texture with Alpha channel. Set the output of the texture object (In/Out tab) to Surface:Transparency In the Bindings tab, click the Edit checkbox and set the bindings so the Transparency's RG and B channels (destination) are set from the source image's A channel At this point I'll mention I can't actually do this because RS's window is busted and has been as long as I've known the software. When I click Edit Binding the Source panel extends to below the bottom of the window and I see no destination panel. No amount of opening and closing windows and panels and Ctrl left right shift click and dragging will expose the rest of the interface for me. The way panels auto scale and such I've always found awkward as they invariably produce a window far longer than my 768 pixel height display, and often don't terminate at the bottom of the window anyway. Anyway, what you are doing is selecting a picture that has Red, Green, Blue and Alpha components, and saying 'For each pixel, take the images Alpha value and set that as the transparency value of the Red, Green and Blue colour components of the surface.' You can just as easily create a black and white image and set the value of surface transparency to the red component of the image, using it as a mask. David Coombes [EMAIL PROTECTED] ... - Original Message - From: [EMAIL PROTECTED] To: user-list@light.realsoft3d.com Sent: Saturday, April 29, 2006 11:56 AM Subject: VSL: Testing an image for an alpha channel Hi, is it possible to test
Re: Testing an image for an alpha channel
On further investigation, this only seems to happen when the material is created - if the channel that I bind doesn't exist in the original image map, RS chooses the R channel for some reason. If the material that initially gets assignes to the Texture object has an alpha channel, I can later change the image to one with no alpha chanell and have the binding intact. Still, since I have to invert the values of the alpha channel, I get bad results from this. The channel aparently always return 0.0 if it doesn't exist. This makes the surface 100% transparent. :( I would like to know if there is a way to test for the prescence of an alpha channel through VSL. I'm not talking about testing the values of the alpha channel - the question is if the image file _has_ an alpha channel or not. Regards, Fredrik Bergholtz On 29/04/06, Matthias Kappenberg [EMAIL PROTECTED] wrote: Why don't use an image without alpha, instead of no image? Matthias Now, some materials will have an image map set in the image map attribute some will not. The materials that has no image map must still function, i.e. the prescence of an image map must be tested by the code in the vsl material. For materials that do have an image map assigned to the image map attribute of the material the material must test if the image it is currently set to has an alpha channel or not. If it has an alpha channel, these values will be mapped to Surfacs:Transparency with a Texture VSL object. If the image that is currently assigned to the image map property does not have an alpha channel, transparency will not be modified by this material. The thing is that, when the user, or the object loader, assigns an image to the attribute, no changes to the VSL code should be done. Just the value of the attribute should have to be changed. The reason for this material is that I want to have a standard material that has all of the features of the game engine I'm making this stuff for. The key thing is to make sure that the materials used doesn't have any features that are not supported by the game engine. When IU have a VSL material that works, the plan is to encapsulate this material in a new material class defined by my plugin. This class would completely restrict modification of the VSL code. Think of how v3materials are used in RS today. I guess that they too are implemented as regular VSL objects, just that the VSL code is hidden from the users and instad a more simple user interface is presented. Does this help, or am I just making stuff even more complicated? ;) Regards, Fredrik Bergholtz On 29/04/06, Matthias Kappenberg [EMAIL PROTECTED] wrote: Something like this? Matthias - Original Message - Wrom: VZCMHVIBGDADRZFSQH To: user-list@light.realsoft3d.com Sent: Saturday, April 29, 2006 1:59 PM Subject: Re: Testing an image for an alpha channel Oh, I think that my description may not have been fully clear. (Bad pun, sorry :) ) I do all this, the thing is that I want to be able to use the same material even if the actual image map has no alpha channel. When I try this, loading an image map with no alpha channel, the bindings get messed up and the red channel will be sent to transparency. This is what I want to avoid. Think of it like a special kind of material, I want to set up a bunch of user editable attributes, one of which is an image map. If this image map contains an alpha channel, that would be sent to transparency, but if it doesn't have an alpha channel, transparency won't be affected by the material. What I want is to make sure that the last three VSL objects in the material shown in the attached image are only evaluated if the image has an alpha channel. Regards, Fredrik Bergholtz On 29/04/06, David Coombes [EMAIL PROTECTED] wrote: Yes, you can do that, but you're thinking about it wrong. What you want to do is output to the surface transparency the value held in an images Alpha channel. In your Surface Properties shader add a Texture object. Load your texture with Alpha channel. Set the output of the texture object (In/Out tab) to Surface:Transparency In the Bindings tab, click the Edit checkbox and set the bindings so the Transparency's RG and B channels (destination) are set from the source image's A channel At this point I'll mention I can't actually do this because RS's window is busted and has been as long as I've known the software. When I click Edit Binding the Source panel extends to below the bottom of the window and I see no destination panel. No amount of opening and closing windows and panels and Ctrl left right shift click and dragging will expose the rest of the interface for me. The way panels auto scale and such I've always found awkward as they invariably produce a window far
Re: Testing an image for an alpha channel
Oh, I think I know why the binding turns out wrong - I never even set up this binding in my plugin code. I just expect the binding to be correct due to the format of the output channel of the trexture object. My bad. I can probably force this binding to be right. But still, it would then give me 0.0 values regardless of the map coords and this means full transparency where I want a completely opaque surface. Regards, Fredrik Bergholtz On 29/04/06, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: On further investigation, this only seems to happen when the material is created - if the channel that I bind doesn't exist in the original image map, RS chooses the R channel for some reason. If the material that initially gets assignes to the Texture object has an alpha channel, I can later change the image to one with no alpha chanell and have the binding intact. Still, since I have to invert the values of the alpha channel, I get bad results from this. The channel aparently always return 0.0 if it doesn't exist. This makes the surface 100% transparent. :( I would like to know if there is a way to test for the prescence of an alpha channel through VSL. I'm not talking about testing the values of the alpha channel - the question is if the image file _has_ an alpha channel or not. Regards, Fredrik Bergholtz On 29/04/06, Matthias Kappenberg [EMAIL PROTECTED] wrote: Why don't use an image without alpha, instead of no image? Matthias Now, some materials will have an image map set in the image map attribute some will not. The materials that has no image map must still function, i.e. the prescence of an image map must be tested by the code in the vsl material. For materials that do have an image map assigned to the image map attribute of the material the material must test if the image it is currently set to has an alpha channel or not. If it has an alpha channel, these values will be mapped to Surfacs:Transparency with a Texture VSL object. If the image that is currently assigned to the image map property does not have an alpha channel, transparency will not be modified by this material. The thing is that, when the user, or the object loader, assigns an image to the attribute, no changes to the VSL code should be done. Just the value of the attribute should have to be changed. The reason for this material is that I want to have a standard material that has all of the features of the game engine I'm making this stuff for. The key thing is to make sure that the materials used doesn't have any features that are not supported by the game engine. When IU have a VSL material that works, the plan is to encapsulate this material in a new material class defined by my plugin. This class would completely restrict modification of the VSL code. Think of how v3materials are used in RS today. I guess that they too are implemented as regular VSL objects, just that the VSL code is hidden from the users and instad a more simple user interface is presented. Does this help, or am I just making stuff even more complicated? ;) Regards, Fredrik Bergholtz On 29/04/06, Matthias Kappenberg [EMAIL PROTECTED] wrote: Something like this? Matthias - Original Message - Wrom: VZCMHVIBGDADRZFSQH To: user-list@light.realsoft3d.com Sent: Saturday, April 29, 2006 1:59 PM Subject: Re: Testing an image for an alpha channel Oh, I think that my description may not have been fully clear. (Bad pun, sorry :) ) I do all this, the thing is that I want to be able to use the same material even if the actual image map has no alpha channel. When I try this, loading an image map with no alpha channel, the bindings get messed up and the red channel will be sent to transparency. This is what I want to avoid. Think of it like a special kind of material, I want to set up a bunch of user editable attributes, one of which is an image map. If this image map contains an alpha channel, that would be sent to transparency, but if it doesn't have an alpha channel, transparency won't be affected by the material. What I want is to make sure that the last three VSL objects in the material shown in the attached image are only evaluated if the image has an alpha channel. Regards, Fredrik Bergholtz On 29/04/06, David Coombes [EMAIL PROTECTED] wrote: Yes, you can do that, but you're thinking about it wrong. What you want to do is output to the surface transparency the value held in an images Alpha channel. In your Surface Properties shader add a Texture object. Load your texture with Alpha channel. Set the output of the texture object (In/Out tab) to Surface:Transparency In the Bindings tab, click the Edit checkbox and set the bindings so the Transparency's RG and B channels (destination
