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Merged
AnyOldName3 merged 10 commits into from
Jan 23, 2026
Merged

OSG side of BPTC support #37

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e549092
Add BC7 DDS texture support
kartoffels123 Jan 7, 2026
8cac637
Handle BC6H/BC7 textures by marking TOP_LEFT origin instead of flipping
kartoffels123 Jan 12, 2026
323e3b8
Clean up. Removes magic numbers, adds some comments.
kartoffels123 Jan 14, 2026
2a44286
Merge branch 'OpenMW:3.6' into 3.6
kartoffels123 Jan 20, 2026
5869cd4
needed for build to have BPTC
kartoffels123 Jan 20, 2026
a51b938
Merge branch '3.6' of https://github.com/kartoffels123/osg into 3.6
kartoffels123 Jan 20, 2026
b194384
Addresses Review:
kartoffels123 Jan 20, 2026
8b723fa
Fix DDS file origin handling in ReaderWriterDDS
kartoffels123 Jan 20, 2026
21449e2
small warning message update.
kartoffels123 Jan 21, 2026
8b255c1
added definition
kartoffels123 Jan 23, 2026
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1 change: 1 addition & 0 deletions include/osg/Image
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Original file line number Diff line number Diff line change
Expand Up @@ -439,6 +439,7 @@ class OSG_EXPORT Image : public BufferData
void ensureValidSizeForTexturing(GLint maxTextureSize);

static bool isPackedType(GLenum type);
static bool isBPTC(GLenum pixelFormat);
static GLenum computePixelFormat(GLenum pixelFormat);
static GLenum computeFormatDataType(GLenum pixelFormat);

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7 changes: 7 additions & 0 deletions include/osg/Texture
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Expand Up @@ -75,6 +75,13 @@
#define GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT 0x8DBE
#endif

#ifndef GL_ARB_texture_compression_bptc
#define GL_COMPRESSED_RGBA_BPTC_UNORM 0x8E8C
#define GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM 0x8E8D
#define GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT 0x8E8E
#define GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT 0x8E8F
#endif

#ifndef GL_IMG_texture_compression_pvrtc
#define GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG 0x8C00
#define GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG 0x8C01
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55 changes: 55 additions & 0 deletions src/osg/Image.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -335,6 +335,20 @@ bool Image::isPackedType(GLenum type)
}
}

bool Image::isBPTC(GLenum pixelFormat)
{
switch(pixelFormat)
{
case(GL_COMPRESSED_RGBA_BPTC_UNORM):
case(GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM):
case(GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT):
case(GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT):
return true;
default:
return false;
}
}


GLenum Image::computePixelFormat(GLenum format)
{
Expand Down Expand Up @@ -707,6 +721,11 @@ unsigned int Image::computeNumComponents(GLenum pixelFormat)
case (GL_COMPRESSED_SRGB8_ALPHA8_ASTC_10x10_KHR) : return 4;
case (GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x10_KHR) : return 4;
case (GL_COMPRESSED_SRGB8_ALPHA8_ASTC_12x12_KHR) : return 4;
// BPTC (BC6H/BC7)
case (GL_COMPRESSED_RGBA_BPTC_UNORM) : return 4;
case (GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM) : return 4;
case (GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT) : return 3;
case (GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT) : return 3;
default:
{
OSG_WARN<<"error pixelFormat = "<<std::hex<<pixelFormat<<std::dec<<std::endl;
Expand All @@ -733,6 +752,11 @@ unsigned int Image::computePixelSizeInBits(GLenum format,GLenum type)
case(GL_COMPRESSED_RED_RGTC1_EXT): return 4;
case(GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT): return 8;
case(GL_COMPRESSED_RED_GREEN_RGTC2_EXT): return 8;
// BPTC (BC6H/BC7) - 128 bits per 4x4 block = 8 bits per pixel
case(GL_COMPRESSED_RGBA_BPTC_UNORM): return 8;
case(GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM): return 8;
case(GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT): return 8;
case(GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT): return 8;
case(GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG): return 4;
case(GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG): return 2;
case(GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG): return 4;
Expand Down Expand Up @@ -892,6 +916,11 @@ osg::Vec3i Image::computeBlockFootprint(GLenum pixelFormat)
case(GL_COMPRESSED_RED_RGTC1_EXT) :
case(GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT) :
case(GL_COMPRESSED_RED_GREEN_RGTC2_EXT) :
// BPTC (BC6H/BC7) - 4x4 blocks
case(GL_COMPRESSED_RGBA_BPTC_UNORM) :
case(GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM) :
case(GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT) :
case(GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT) :
case(GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG) :
case(GL_COMPRESSED_RGBA_PVRTC_4BPPV1_IMG) :
case(GL_ETC1_RGB8_OES) :
Expand Down Expand Up @@ -971,6 +1000,13 @@ unsigned int Image::computeBlockSize(GLenum pixelFormat, GLenum packing)
case(GL_COMPRESSED_RED_GREEN_RGTC2_EXT):
return osg::maximum(16u,packing); // block size of 16

// BPTC (BC6H/BC7) - 16 bytes per block
case(GL_COMPRESSED_RGBA_BPTC_UNORM):
case(GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM):
case(GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT):
case(GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT):
return osg::maximum(16u,packing); // block size of 16

case(GL_COMPRESSED_RGB8_ETC2):
case(GL_COMPRESSED_SRGB8_ETC2):
case(GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2):
Expand Down Expand Up @@ -1021,6 +1057,17 @@ unsigned int Image::computeBlockSize(GLenum pixelFormat, GLenum packing)

unsigned int Image::computeRowWidthInBytes(int width,GLenum pixelFormat,GLenum type,int packing)
{
// Handle block-compressed formats (S3TC, RGTC, BPTC, etc.)
// Prevents stride/pitch misalignment. Surprised this didn't come up sooner on the S3TC formats.
int blockSize = computeBlockSize(pixelFormat, 0);
if (blockSize > 0) {
osg::Vec3i footprint = computeBlockFootprint(pixelFormat);
int blocksWide = (width + footprint.x() - 1) / footprint.x();
unsigned int size = blockSize * blocksWide;
return roudUpToMultiple(size, packing);
}

// Non-compressed formats
unsigned int pixelSize = computePixelSizeInBits(pixelFormat,type);
int widthInBits = width*pixelSize;
int packingInBits = packing!=0 ? packing*8 : 8;
Expand Down Expand Up @@ -1822,6 +1869,14 @@ void Image::flipVertical()
return;
}

// BPTC (BC6H/BC7) textures cannot be flipped in compressed form due to complex per-block encoding.
// Callers should check isBPTC() and set TOP_LEFT origin instead of calling flipVertical().
if (Image::isBPTC(_pixelFormat))
{
OSG_WARN << "Image::flipVertical(): BPTC (BC6H/BC7) textures cannot be flipped in compressed form." << std::endl;
return;
}

unsigned int rowSize = getRowSizeInBytes();
unsigned int rowStep = getRowStepInBytes();

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27 changes: 23 additions & 4 deletions src/osg/Texture.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -199,10 +199,10 @@ InternalPixelRelations compressedInternalFormats[] = {
, { GL_COMPRESSED_SIGNED_RED_RGTC1_EXT , GL_RED , GL_COMPRESSED_SIGNED_RED_RGTC1_EXT }
// , { GL_COMPRESSED_RG_RGTC2 , GL_RG , GL_COMPRESSED_RG_RGTC2 }
// , { GL_COMPRESSED_SIGNED_RG_RGTC2 , GL_RG , GL_COMPRESSED_SIGNED_RG_RGTC2 }
// , { GL_COMPRESSED_RGBA_BPTC_UNORM , GL_RGBA , GL_COMPRESSED_RGBA_BPTC_UNORM }
// , { GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM , GL_RGBA , GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM }
// , { GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT , GL_RGB , GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT }
// , { GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT , GL_RGB , GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT }
, { GL_COMPRESSED_RGBA_BPTC_UNORM , GL_RGBA , GL_COMPRESSED_RGBA_BPTC_UNORM }
, { GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM , GL_RGBA , GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM }
, { GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT , GL_RGB , GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT }
, { GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT , GL_RGB , GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT }

, { GL_COMPRESSED_RGB_S3TC_DXT1_EXT , GL_RGB , GL_COMPRESSED_RGB_S3TC_DXT1_EXT }
, { GL_COMPRESSED_RGBA_S3TC_DXT1_EXT , GL_RGBA , GL_COMPRESSED_RGBA_S3TC_DXT1_EXT }
Expand Down Expand Up @@ -377,6 +377,12 @@ void Texture::TextureProfile::computeSize()
case GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT: numBitsPerTexel = 8; break;
case GL_COMPRESSED_RED_GREEN_RGTC2_EXT: numBitsPerTexel = 8; break;

// BPTC (BC6H/BC7)
case GL_COMPRESSED_RGBA_BPTC_UNORM: numBitsPerTexel = 8; break;
case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM: numBitsPerTexel = 8; break;
case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT: numBitsPerTexel = 8; break;
case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT: numBitsPerTexel = 8; break;

case GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG: numBitsPerTexel = 2; break;
case GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG: numBitsPerTexel = 2; break;
case GL_COMPRESSED_RGB_PVRTC_4BPPV1_IMG: numBitsPerTexel = 4; break;
Expand Down Expand Up @@ -1898,6 +1904,11 @@ bool Texture::isCompressedInternalFormat(GLint internalFormat)
case (GL_COMPRESSED_RED_RGTC1_EXT):
case (GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT):
case (GL_COMPRESSED_RED_GREEN_RGTC2_EXT):
// BPTC (BC6H/BC7)
case (GL_COMPRESSED_RGBA_BPTC_UNORM):
case (GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM):
case (GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT):
case (GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT):
case (GL_ETC1_RGB8_OES):
case (GL_COMPRESSED_RGB8_ETC2):
case (GL_COMPRESSED_SRGB8_ETC2):
Expand Down Expand Up @@ -1969,6 +1980,9 @@ void Texture::getCompressedSize(GLenum internalFormat, GLint width, GLint height
blockSize = 8;
else if (internalFormat == GL_COMPRESSED_RED_GREEN_RGTC2_EXT || internalFormat == GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT)
blockSize = 16;
// BPTC (BC6H/BC7) - 128 bits per block
else if (internalFormat == GL_COMPRESSED_RGBA_BPTC_UNORM || internalFormat == GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM || internalFormat == GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT || internalFormat == GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT)
blockSize = 16;
else if (internalFormat == GL_COMPRESSED_RGBA_PVRTC_2BPPV1_IMG || internalFormat == GL_COMPRESSED_RGB_PVRTC_2BPPV1_IMG)
{
blockSize = 8 * 4; // Pixel by pixel block size for 2bpp
Expand Down Expand Up @@ -2397,6 +2411,11 @@ void Texture::applyTexImage2D_load(State& state, GLenum target, const Image* ima
case(GL_COMPRESSED_SIGNED_RG11_EAC):
case GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT:
case GL_COMPRESSED_RED_GREEN_RGTC2_EXT: _internalFormat = GL_RG; break;
// BPTC (BC6H/BC7)
case GL_COMPRESSED_RGBA_BPTC_UNORM:
case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM: _internalFormat = GL_RGBA; break;
case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT:
case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT: _internalFormat = GL_RGB; break;
}
}

Expand Down
30 changes: 29 additions & 1 deletion src/osgPlugins/dds/ReaderWriterDDS.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -814,6 +814,30 @@ osg::Image* ReadDDSFile(std::istream& _istream, bool flipDDSRead)
pixelFormat = GL_COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT;
break;

case OSG_DXGI_FORMAT_BC6H_UF16:
internalFormat = GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT;
pixelFormat = GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT;
packing = 4; // 8 bits/pixel. 4 px = 4 bytes
break;

case OSG_DXGI_FORMAT_BC6H_SF16:
internalFormat = GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT;
pixelFormat = GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT;
packing = 4; // 8 bits/pixel. 4 px = 4 bytes
break;

case OSG_DXGI_FORMAT_BC7_UNORM:
internalFormat = GL_COMPRESSED_RGBA_BPTC_UNORM;
pixelFormat = GL_COMPRESSED_RGBA_BPTC_UNORM;
packing = 4; // 8 bits/pixel. 4 px = 4 bytes
break;

case OSG_DXGI_FORMAT_BC7_UNORM_SRGB:
internalFormat = GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM;
pixelFormat = GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM;
packing = 4; // 8 bits/pixel. 4 px = 4 bytes
break;

default:
OSG_WARN << "ReadDDSFile warning: unhandled DX10 pixel format 0x"
<< std::hex << std::setw(8) << std::setfill('0')
Expand Down Expand Up @@ -1100,7 +1124,11 @@ osg::Image* ReadDDSFile(std::istream& _istream, bool flipDDSRead)

if (mipmap_offsets.size()>0) osgImage->setMipmapLevels(mipmap_offsets);

if (flipDDSRead) {
osgImage->setOrigin(osg::Image::TOP_LEFT);

// BPTC (BC6H/BC7) textures cannot be flipped in compressed form
if (flipDDSRead && !osg::Image::isBPTC(internalFormat))
{
osgImage->setOrigin(osg::Image::BOTTOM_LEFT);
if (!isDXTC || ((s>4 && s%4==0 && t>4 && t%4==0) || s<=4)) // Flip may crash (access violation) or fail for non %4 dimensions (except for s<4). Tested with revision trunk 2013-02-22.
{
Expand Down