StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

POTrying to figure out a specific alpha mask application using IDirect3D9#SetTextureStageState
primarykey
Id
8814267
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
4
CommunityOwnedDate
CreationDate
2012-01-11T04:45:46.437
FavoriteCount
0
LastActivityDate
2012-01-11T13:29:19.920
LastEditDate
2012-01-11T13:29:19.920
LastEditorUserId
218512
OwnerUserId
218512
ParentId
0
PostTypeId
1
Score
0
ViewCount
114
LastEditorDisplayName
text
Body
I'm trying to create a system where I can cause a fadeout on a texture using a second texture as an alpha mask. I load the color texture in stage 0 and the mask texture in stage 1. I can get them to stage correctly so that the alpha values are based on the mask and I can get the fade to come in and out by using a sliding D3DTA_CONSTANT. The problem is that I'm trying to create a specific behavior that I can't seem to get out of the available D3DTA. Basically I want to have 2 values, one called 'step' and the other called 'vague'. The 'vague' value will remain constant throughout the effect and the 'step' argument will either start at 0 and increase to 255 over several frames. I'm trying to create the following behavior: *Texels with mask-alpha values below the value of 'step' draw with zero alpha. *Texels with mask-alpha values above 'step' + 'vague' draw with 255 alpha. *Texels with mask-alpha values in the range between 'step' and ('step' + 'vague') draw with alpha scaled such that alpha 'step' is zero alpha and alpha ('step' + 'vague') draws with max alpha. Here's a graph showing the function since it's hard to explain in words: <a href="http://imageshack.us/photo/my-images/834/desiredalphamaskfunctio.png/" rel="nofollow">http://imageshack.us/photo/my-images/834/desiredalphamaskfunctio.png/</a> The main problem that I'm running into is that I can't figure out how to configure the texture stages so that the middle range (between step and step+vague) to "stretch" its values between 0 and 255. There's no direct division or multiplication, just modulation, so I can't do it the obvious way, but I'm pretty sure that there's a way to do it that just hasn't occurred to me yet. (I had some hope for D3DTOP_MULTIPLYADD, but the 'multiply' turned out to just be another modulate.) Anyone have any ideas? Thanks in advance for any advice.
Tags
<graphics><directx-9><alpha-transparency>
Title
Trying to figure out a specific alpha mask application using IDirect3D9#SetTextureStageState
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USKhatharr
UserOwnerUserId
1. USKhatharr
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.