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ID Category Severity Reproducibility Date Submitted Last Update
0000595 [Croquet] Jasmine minor always 12-03-04 21:04 12-11-04 19:43
Reporter elenzil View Status public  
Assigned To
Priority normal Resolution fixed  
Status resolved  
Summary 0000595: alpha < 1 in ambientColor turns off zbuffer writing.
Description If a material's ambient color has alpha less than one,
z-buffer writing is turned off when the object is rendered.

However, as far as i can see,
the alpha component of the ambient color has no other effect on rendering.
ie, you can't actually affect the transparency of an object with ambient material.

It seems like ambient alpha should only turn off zbuffer writing
if it's actually going to render polygons transparent.

Also,
the default values for a material's ambient color are .5 .5 .5 .5,
which means that when you just make a new material and assign it to
an object, unless you set the ambient color to (r g b 1),
you will get weird zbufferless rendering of objects.

See attached screenshots.
Additional Information
Attached Files  ambientalpha.png [^] (194,297 bytes) 12-03-04 21:04
 ambientalpha2.png [^] (166,290 bytes) 12-10-04 21:24
 FixAmbientAlpha.1.cs [^] (317 bytes) 12-10-04 21:24

- Relationships

- Notes
(0000897 - 49 - 49 - 49 - 49 - 49 - 49)
elenzil
12-10-04 21:25

second snapshot and changeset with fix updloaded.
 
(0000900 - 51 - 51 - 51 - 51 - 51 - 51)
Croqueteer
12-10-04 23:36

Presume that fix logged at 645 resolves this issue.
 
(0000901 - 171 - 195 - 195 - 195 - 195 - 195)
elenzil
12-11-04 00:16

Howdy.
645 does work around this issue
by setting the default ambient alpha value to one,
but does not include the deeper (very simple) fix
which is in this changeset.
 
(0000907 - 185 - 185 - 185 - 185 - 185 - 185)
Croqueteer
12-11-04 19:43

I checked the OGL reference and Orion is correct. I also modified the default materials to OpenGL defaults. I did not modify the lights to the defaults, as these were simply too harsh.
 

- Issue History
Date Modified Username Field Change
12-03-04 21:04 elenzil New Issue
12-03-04 21:04 elenzil File Added: ambientalpha.png
12-10-04 21:24 elenzil File Added: ambientalpha2.png
12-10-04 21:24 elenzil File Added: FixAmbientAlpha.1.cs
12-10-04 21:25 elenzil Note Added: 0000897
12-10-04 23:36 Croqueteer Status new => resolved
12-10-04 23:36 Croqueteer Resolution open => fixed
12-10-04 23:36 Croqueteer Assigned To  => Croqueteer
12-10-04 23:36 Croqueteer Note Added: 0000900
12-10-04 23:36 Croqueteer Assigned To Croqueteer =>
12-11-04 00:16 elenzil Status resolved => feedback
12-11-04 00:16 elenzil Resolution fixed => reopened
12-11-04 00:16 elenzil Note Added: 0000901
12-11-04 19:43 Croqueteer Status feedback => resolved
12-11-04 19:43 Croqueteer Resolution reopened => fixed
12-11-04 19:43 Croqueteer Assigned To  => Croqueteer
12-11-04 19:43 Croqueteer Note Added: 0000907
12-11-04 19:43 Croqueteer Assigned To Croqueteer =>


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