MorphZone

*FIXED* Problem with black transparency.

AmiDARK

# 1

Caterpillar

Posts: 38 from 2011/10/29

From: South France

Hi All,

I have fixed the crashes I had in the MorphOS version of the AmiDARK engine and nearly everything run fine.
But, I have a problem.
When I set transparency to 1 on a 3D Object, the 3D object disappear.

On AmigaOS4.1 the transparency work perfectly (MiniGL/OpenGL) but not on MorphOS.

Here is the details for cases 0 & 1. 0 = no transparency, 1 = black is not visible
Code:

    switch( MyObjectMesh->Transparency ){
      case 0:                                                  // 0 - First Phase rendering NO ALPHA
        glEnable( GL_BLEND );
        glBlendFunc( GL_ONE, GL_ZERO );
        glDisable( GL_ALPHA_TEST );
        glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
        glTexEnvf( GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE );
        break;
      case 1:                                                  // 1 - First Phase WITH ALPHA MASKING
        glEnable( GL_BLEND );
        glEnable( GL_DEPTH_TEST );
        glEnable( GL_ALPHA_TEST );
        glAlphaFunc( GL_EQUAL, 0 );
        glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
        glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
        glTexEnvf( GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE );
        break;

Does anyone have any clue ?

[ Edité par AmiDARK 19.01.2012 - 14:28 ]

»16.01.12 - 21:06

kiero

# 2
MorphOS Developer

Posts: 129 from 2003/2/28

if i'm not mistaken here is why:

case 1: // 1 - First Phase WITH ALPHA MASKING
glEnable( GL_BLEND );
glEnable( GL_DEPTH_TEST );
glEnable( GL_ALPHA_TEST );
glAlphaFunc( GL_EQUAL, 0 ); <---- only pass fragments with alpha value of 0
glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA ); <--- blend using source fragment alpha
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
glTexEnvf( GL_TEXTURE_ENV, GL_COMBINE_ALPHA, GL_REPLACE );
break;

now combine these two rules and you get that only fragments with alpha == 0 are drawn and they are invisible because of the second rule. if this is not the case then prepare some >simple< test code and i will try to verify. and please, don't use amigaos minigl as a reference. if you want to check something run it through software implementation (mesa) or on pc.
»17.01.12 - 21:39

AmiDARK

# 3
Caterpillar

Posts: 38 from 2011/10/29

From: South France

Excuse, GL_EQUAL was the last test done.
Defaut value was "GL_NOTEQUAL, 0"
What is strange is that under AmigaOS4.x it work perfectly with GL_NOTEQUAL, 0 and not under MorphOS ... Objects are not displayed.

I don't use PC for development and, firstly, the AmiDARK Engine was developed on AmigaOS 4.x ... Now, I can adapt it to MorphOS cos I have an Efika ... but before it was only for AmigaOS4.x ... This is why AmigaOS 4.x is my reference.

[ Edité par AmiDARK 17.01.2012 - 23:18 ]
»17.01.12 - 23:16

raistlin77it

# 4
Order of the Butterfly

Posts: 186 from 2003/10/23

sorry for the off topic, but i see kiero online :D

Kiero can u put an eye and watch this problem ?

https://morph.zone/modules/newbb_plus/viewtopic.php?forum=49&topic_id=7895&post_id=84425&viewmode=flat&sortorder=1&showonepost=1
I'm nerdy in the extreme
And whiter than sour cream

White&Nerdy 2006 Al Yankovic
»18.01.12 - 11:23

AmiDARK

# 5

Caterpillar

Posts: 38 from 2011/10/29

From: South France

Hi,

I've fixed my issue using this :

Code:

        glEnable( GL_DEPTH_TEST );
        glBlendFunc( GL_ONE, GL_ZERO );
        glEnable( GL_BLEND );
        glAlphaFunc( GL_NOTEQUAL, 0.0f );
        glEnable( GL_ALPHA_TEST );
        glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

Kindest Regards,
AmiDARK

»19.01.12 - 14:28