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ReJ
Joined: 04 Apr 2004
Posts: 25
Location: Lithuania, Vilnius
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 Posted: Thu Jul 21, 2005 11:08 pm Post subject: Texture coordinates generation, projection. Unknown states. |
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Hi,
Recently, while playing with texture projection, I've discovered the following things:
1) sceGuEnable( 19 )
does flipping of the normal, which affects both lighting ant texture projection
2) sceGuTexMapMode( arg0, arg1, arg2 )
arg0 (0-3?):
0 - disables texture projection, enables sceGuTexOffset/Scale.
1 - enables texture coordinates generation. Uses matrix (spcified as GU_TEXTURE) to transform source 2d/3d vector. Source vector is a vertex component specified using sceGuTexProjMapMode. Disables sceGuOffset/Scale. Strangely enough, source vectors are in object space, _not_ post-transformed ones.
2 - ? (sampled texels seems to be uniform other the poly, but somewhat darker than pure white)
3 - ?
arg1, arg2: ??? (no effect)
sceGuTexProjMapMode( arg0 )
arg0 (0-3) source for texture coord calculation, is multiplied by GU_TEXTURE and projected into 2d if necessary:
0 - position in object space, resulting 3d vector is projected into 2d
1 - object UV
2 - normalized normal, resulting 3d vector is projected into 2d
3 - not-normalized normal, resulting 3d vector is projected into 2d
3) sceGuEnable( 15 )
uses post-transformed and projected object position as a 2d texture coordinates. Omits both UV specified in vertices and generated texture coordinates. Is not affected by sceGuTexOffset/Scale or GU_TEXTURE.
4) sceGuEnable( 21 )
seems to multiply resulting fragment (after applying texture function) by 2.
Hope that provides some usefull information. |
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adresd
Joined: 17 Jan 2004
Posts: 43
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| Posted: Fri Jul 22, 2005 12:12 am Post subject: |
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| Quote: |
2) sceGuTexMapMode( arg0, arg1, arg2 )
arg0 (0-3?):
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arg0 = 2 seems to be envmap mode
still playing with it |
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ReJ
Joined: 04 Apr 2004
Posts: 25
Location: Lithuania, Vilnius
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| Posted: Fri Jul 22, 2005 9:17 pm Post subject: |
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| adresd wrote: |
arg0 = 2 seems to be envmap mode
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Yeah, seems to be the envmap mode. Although the envmap matrix setup is a bit strange, that's what I've figured out:
The envmap matrix (2x3) is specified as a combination of 2 columns. Columns can be set using sceGuLight() [sic!] as a light position (maybe it's some kind of error in pspgulib?). So 4 different columns can be specified. The actual envmap matrix is assembled specifying column indices using sceGuTexMapMode().
The UV coordinates (calculated by GU/GE from normals) are multiplied by the envmap matrix (2x3) to generate actual texture UV coords.
sceGuTexMapMode( arg0, arg1, arg2 )
arg0: 2 - envmap mode
arg1 (0-3): index of the 1st column for the envmap matrix (2x3)
arg2 (0-3): index of the 2nd column
it may look abit strange, but it works:
| Code: | ScePspFVector3 columns[4] = {
{ 0.707f, 0.707f, 0.0f }, // cos(a), sin(a), tx
{ -0.707f, 0.707f, 0.0f }, // -sin(a), cos(a), ty
{ 0.86f, 0.5f, 0.0f },
{ -0.5f, 0.86f, 0.0f }
};
sceGuLight( 0, GU_DIRECTIONAL, GU_DIFFUSE, &columns[0] );
sceGuLight( 1, GU_DIRECTIONAL, GU_DIFFUSE, &columns[1] );
sceGuLight( 2, GU_DIRECTIONAL, GU_DIFFUSE, &columns[2] );
sceGuLight( 3, GU_DIRECTIONAL, GU_DIFFUSE, &columns[3] );
sceGuTexProjMapMode( 0 );
sceGuTexMapMode( 2, 0, 1 ); // rotate envmap 45 degrees
//sceGuTexMapMode( 2, 2, 3 ); // rotate envmap 30 degrees
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adresd
Joined: 17 Jan 2004
Posts: 43
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| Posted: Fri Jul 22, 2005 11:14 pm Post subject: |
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| Nice work, that works nicely :) |
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ReJ
Joined: 04 Apr 2004
Posts: 25
Location: Lithuania, Vilnius
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| Posted: Sat Jul 23, 2005 7:11 pm Post subject: |
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Thanks :)
I did a sample showing environment mapping:
http://rej.50megs.com/psp/envmap
Last edited by ReJ on Sat Jul 23, 2005 10:54 pm; edited 1 time in total |
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chp
Joined: 23 Jun 2004
Posts: 313
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| Posted: Sat Jul 23, 2005 10:29 pm Post subject: |
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Good work! I'll update GU right away with this information, and I'll update your sample to use these new defines aswell.
The new defines will be:
| Code: |
/* States*/
#define GU_FACE_NORMAL_REVERSE (19)
#define GU_FRAGMENT_2X (21)
/* Texture Map Mode */
#define GU_TEXTURE_COORDS (0)
#define GU_TEXTURE_MATRIX (1)
#define GU_ENVIRONMENT_MAP (2)
/* Texture Projection Map Mode */
#define GU_POSITION (0)
#define GU_UV (1)
#define GU_NORMALIZED_NORMAL (2)
#define GU_NORMAL (3)
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If you think they should be named differently, let me know.
_________________
GE Dominator |
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jsgf
Joined: 12 Jul 2005
Posts: 254
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| Posted: Mon Aug 01, 2005 4:21 pm Post subject: Re: Texture coordinates generation, projection. Unknown stat |
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| ReJ wrote: |
2 - ? (sampled texels seems to be uniform other the poly, but somewhat darker than pure white) |
Could it be some other lighting thing? Shadows? I don't suppose there's any support for depth textures? |
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ReJ
Joined: 04 Apr 2004
Posts: 25
Location: Lithuania, Vilnius
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| Posted: Sun Aug 07, 2005 6:35 pm Post subject: Re: Texture coordinates generation, projection. Unknown stat |
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| jsgf wrote: | | ReJ wrote: |
2 - ? (sampled texels seems to be uniform other the poly, but somewhat darker than pure white) |
Could it be some other lighting thing? Shadows? I don't suppose there's any support for depth textures? |
As it is already discovered, 2 is an environment mapping mode. |
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