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Re: [gl4java-usergroup] Follow-up texture-mapping questions
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From: Pepijn V. E. <pep...@lu...> - 2003-03-23 11:34:57
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OpenGL does not require square textures. If in practice it is necessary =20=
to use square textures, it's a driver/hardware limitation.
The problem is probably that your hardware can't handle textures that =20=
are that big. A lot of consumer level cards can only handle textures up =20=
to 1024x1024. You can query this maximum value using glGetIntegerv( =20
GL_MAX_TEXTURE_SIZE ).
Pepijn Van Eeckhoudt
On zondag, maa 23, 2003, at 11:38 Europe/Brussels, Florent Geffroy =20
wrote:
> I think the error occurs because your 2048*1024
> texture is not a square. I think OpenGL can only
> handle square textures !
> You'll need to add black rectangles on both parts of
> your image, in order to have a 2048*2048 one, and then
> play with the texture coordinates of your polygon...
>
> Hope this helps...
>
> --- Mark Montana <pat...@lm...> a
> =E9crit=A0: > All,
>>
>> Follow up texture-mapping questions...
>>
>> First, I fixed my original problem that was causing
>> textures in my application to
>> be all white. I had a special initialization method
>> to set all the texture mapping
>> parameters. I forgot to surround those GL calls
>> with:
>> glc.getGLContext().gljMakeCurrent(); AND
>> glc.getGLContext().gljFree();
>> A rather newbie-sounding mistake, but it's been a
>> while since I wrote rendering
>> code in GL4Java. I hate that you have to perform
>> those steps in the non-draw
>> methods, but I realize it is a necessary evil
>> (Magician had the same thing).
>>
>> On to my 2 new questions (somewhat more advanced):
>>
>> (Q1) I am loading fairly large textures of satellite
>> imagery of the Earth. Two of
>> them are 1024x1024 (powers of two) in RGB format.
>> These two images load and render
>> just fine. The third texture is 2048x1024 (also
>> powers of two) in RGB format. This
>> one gets a GL error during my call to
>> glTexImage2d(), and the error is "invalid
>> value." I determined that value that makes it
>> unhappy is the image width (2048).
>> If I lie to OpenGL and tell it that the width is
>> only1024, the image loads and
>> renders without an error (of course it looks screwed
>> up, but I expect that since I
>> lied about the true width). Any insight on why it
>> cannot handle the 2048 width?
>>
>> I know that it is not related to the hardware,
>> graphics card, graphics card
>> driver, or machine configuration. I know this
>> because our application is half
>> GL4Java and half Java3D. The Java3D display loads
>> the same exact textures and
>> renders them with no problem. I also do not think it
>> is related to the total
>> amount of texture memory available; again because
>> Java3D has no problem, and I can
>> disable the Java3D display and disable to two
>> 1024x1024 textures in the GL4Java
>> display...and the GL4Java display still gets the
>> same error on the 2048x1024
>> texture.
>>
>> Could it have something to do with the OpenGL
>> context or configuration that I am
>> requesting???
>> Could it be related to the fact that I am using
>> display-lists???
>>
>> [[ I inserted my texture mapping method at the
>> bottom of this message. ]]
>>
>> (Q2) My textures are rendered in a 2D display, no
>> lighting, no normals, no
>> materials. The polygons underneath the texture are
>> white. The texture comes out
>> way to dark with GL_DECAL or GL_REPLACE. When I try
>> GL_MODULATE or GL_BLEND, it
>> gets really washed-out. We had this same exact
>> problem in the Java3D display with
>> these textures. We fixed it there by using some
>> texture-environment settings that
>> are unique to Java3D. (In other words, the Java3D
>> people used some of the more
>> advanced features of blending functions and/or
>> filters to create a new blending
>> equation that works well.) I was considering a
>> decompile of the Java3D code to see
>> how they did it, but I thought I would as for some
>> advice on this problem first.
>>
>>
> =
-----------------------------------------------------------------------=20=
> -----------------
>>
>> My texture map initialization code (sorry for the
>> formatting if your mail tool
>> doesn't support fixed-width fonts):
>>
>>
>> private void initialize()
>> {
>> // Must make the GLComponent's OpenGL context
>> current when outside a
>> // GLEventListener callback method. Then don't
>> forget to unlock() it.
>>
>> glc.getGLContext().gljMakeCurrent(); //
>> Make current to call OpenGL
>>
>>
>> GeoTiffImage image =3D
>> geoTiffDef.getGeoTiffImage();
>> Raster raster =3D image.getAsRaster();
>> Object data =3D raster.getDataElements(
>> 0, 0,
>>
>> raster.getWidth(),
>>
>> raster.getHeight(),
>>
>> null );
>>
>> if( ToolkitConstants.TK_DEBUG_PATCH2D =3D=3D true
>> )
>> {
>> if( raster.getTransferType() =3D=3D
>> DataBuffer.TYPE_BYTE )
>> System.out.println( "Texture storage
>> type =3D TYPE_BYTE");
>> else
>> {
>> System.err.println(
>> "TexturedPatch2d.initialize() - " +
>> "What is the texture
>> storage type?");
>> System.err.flush();
>> }
>>
>> System.out.println( "Num data elements =3D "
>> +
>>
>> raster.getNumDataElements() );
>> System.out.println( "Geotiff size =3D (" +
>> raster.getWidth() + ", "
>> +
>> raster.getHeight() + ")" );
>> }
>>
>>
>> // Set unpacking to use 1 byte allignment
>> gl_.glPixelStorei( GLEnum.GL_UNPACK_ALIGNMENT,
>> 1 );
>>
>> // Ask for valid, unused texture name
>> gl_.glGenTextures( 1, textureName );
>>
>> // Bind a texture object to the name
>> gl_.glBindTexture( GLEnum.GL_TEXTURE_2D,
>> textureName[0] );
>>
>> // Set clamping preferences
>> gl_.glTexParameteri( GLEnum.GL_TEXTURE_2D,
>> GLEnum.GL_TEXTURE_WRAP_S,
>> GLEnum.GL_CLAMP );
>> gl_.glTexParameteri( GLEnum.GL_TEXTURE_2D,
>> GLEnum.GL_TEXTURE_WRAP_T,
>> GLEnum.GL_CLAMP );
>>
>> // Set mag and min filter preferences
>> gl_.glTexParameteri( GLEnum.GL_TEXTURE_2D,
>> GLEnum.GL_TEXTURE_MAG_FILTER,
>> GLEnum.GL_NEAREST );
>> gl_.glTexParameteri( GLEnum.GL_TEXTURE_2D,
>> GLEnum.GL_TEXTURE_MIN_FILTER,
>> GLEnum.GL_NEAREST );
>>
>> gl_.glTexEnvi( GLEnum.GL_TEXTURE_ENV,
>> GLEnum.GL_TEXTURE_ENV_MODE,
>> GLEnum.GL_MODULATE ); //
>> GL_REPLACE, GL_BLEND, GL_DECAL
>>
>> gl_.glHint(
>> GLEnum.GL_PERSPECTIVE_CORRECTION_HINT,
>> GLEnum.GL_FASTEST );
>>
>> // Define the 2D texture
>> gl_.glTexImage2D( GLEnum.GL_TEXTURE_2D, 0,
>> GLEnum.GL_RGB,
>> raster.getWidth()/2,
>> raster.getHeight(),
>> 0, GLEnum.GL_RGB,
>> GLEnum.GL_UNSIGNED_BYTE,
>> (byte[]) data );
>>
>>
>> if( ToolkitConstants.TK_DEBUG_PATCH2D =3D=3D true
>> )
>> {
>> int errorCode =3D GLEnum.GL_NO_ERROR;
>>
>> if( (errorCode =3D gl_.glGetError()) !=3D
>> GLEnum.GL_NO_ERROR )
>> {
>> System.err.println(
>> "TexturedPatch2d.initialize() - " +
>> "GL Error: " +
>> glu_.gluErrorString(errorCode) );
>> System.err.flush();
>> }
>> }
>>
>>
> =3D=3D=3D message truncated =3D=3D=3D
>
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