Added ETC1 support to GLES2

[Wolfmanfx]

I have added ETC1 support here (PKM CODEC)

https://bitbucket.org/wolfmanfx/ogre/ch ... 57988f187e

i tested it with a pkm texture which were generated with the etc1tool. ETC1 do not support an alpha channel and mipmap generation is disabled atm.
The test device was a tegra2 so i would be happy if you guys could test it - this should also work on iOS.

best regards

[oiram]

Great work!
I have added KTX support base on it, and it was tested that works fine.
https://sourceforge.net/tracker/?func=d ... tid=302997

And will you review these?

[Wolfmanfx]

I will review and test it asap. Nice

[oiram]

Waiting for your good news.

[Wolfmanfx]

Just checked it and it seems so that you just load the image but not the compressed mips.

[oiram]

Yes, I just load the image.
Load the compressed mips for ETC1Codec is the next thing we must to do.

Here is sample code:
http://www.khronos.org/opengles/sdk/tools/KTX

[oiram]

Ah, another thing, this is your code:
@RenderSystems/GLES2/src/OgreGLES2PixelFormat.cpp

Code: Select all

#if OGRE_NO_ETC1_CODEC == 0
            case PF_ETC1_RGB8:
                return GL_ETC1_RGB8_OES;
#endif
...
lalalala...

my update code:

Code: Select all

#if GL_OES_compressed_ETC1_RGB8_texture
            case PF_ETC1_RGB8:
                return GL_ETC1_RGB8_OES;
#endif
...
lalalala...

use "GL_OES_compressed_ETC1_RGB8_texture" replace "OGRE_NO_ETC1_CODEC == 0", am I right?

[oiram]

I've done.
Here is the KTX file structure from http://www.khronos.org/opengles/sdk/too ... ormat_spec:

Code: Select all

Byte[12] identifier
UInt32 endianness
UInt32 glType
UInt32 glTypeSize
UInt32 glFormat
Uint32 glInternalFormat
Uint32 glBaseInternalFormat
UInt32 pixelWidth
UInt32 pixelHeight
UInt32 pixelDepth
UInt32 numberOfArrayElements
UInt32 numberOfFaces
UInt32 numberOfMipmapLevels
UInt32 bytesOfKeyValueData
  
for each keyValuePair that fits in bytesOfKeyValueData
    UInt32   keyAndValueByteSize
    Byte     keyAndValue[keyAndValueByteSize]
    Byte     valuePadding[3 - ((keyAndValueByteSize + 3) % 4)]
end
  
for each mipmap_level in numberOfMipmapLevels*
    UInt32 imageSize; 
    for each array_element in numberOfArrayElements*
       for each face in numberOfFaces
           for each z_slice in pixelDepth*
               for each row or row_of_blocks in pixelHeight*
                   for each pixel or block_of_pixels in pixelWidth
                       Byte data[format-specific-number-of-bytes]**
                   end
               end
           end
           Byte cubePadding[0-3]
       end
    end
    Byte mipPadding[3 - ((imageSize + 3) % 4)]
end

I found the PVRTexLib of imgtech save incorrect KTX file that missed "UInt32 imageSize;" before every MIPMaps level compressed pixel data.
Mali GPU Texture Compression Tool is corrected.

Another issue with your original code:
@OgrePixelFormat.cpp

Code: Select all

...
case PF_ETC1_RGB8:
    return ((width * height) >> 1);
...

Because the min texture width/height of ETC is 4, that means 4x4, 2x2, 1x1 MIPMaps image size are same as 8 bytes.
Basically, 8 bytes is the minimum texture size. Smaller textures are padded up to 8 bytes.
Here is new code:

Code: Select all

...
case PF_ETC1_RGB8:
    return std::max(8, (int)(width * height) >> 1);
...

And, when I verify MIPMaps with OpenGL ES2 rendersystem, I found texture filtering must set to trilinear. If filtering set to bilinear, only MIPMap level 0 is used.
For verify this issue, I make red colour to MIPMap level 0 and make blue colour to level 1, and zoom in/out camera for observed.
D3D and OpenGL are both correct, it's an issue only with OpenGL ES2. I think maybe something wrong with it.

coded attached.

[oiram]

incorrect KTX file structure issue confirmed.
http://www.imgtec.com/forum/forum_posts ... -pvrtexlib

[oiram]

These day SourceForge is blocked to me in our country.
I'll update the patch asap when SF is fixed.

Anyone can review the code?

[Wolfmanfx]

Hi,

It do not help when you send me pm's with "please review" moreover i have to test it on my site on a device (android/iOS) and verify its working and also i am just back from vacation today so do not except miracles

[oiram]