GL: add an important bit of tribal knowledge.

doc/opengl-support.dox

@@ -579,6 +579,8 @@ add any performance gains, is not supported in Magnum. See also
     supported exclusively by NVidia
 -   @gl_extension{ARB,cl_event} seems to be not supported anywhere
 -   @gl_extension{ARB,shader_stencil_export} is supported exclusively by AMD
+-   @gl_extension{EXT,texture_compression_latc} is superseded by
+    @gl_extension{EXT,texture_compression_rgtc}, available in OpenGL 3.0.
 
 @subsection opengl-unsupported-extensions-vendor Unsupported vendor extensions
 

src/Magnum/GL/PixelFormat.h

@@ -712,8 +712,11 @@ enum class CompressedPixelFormat: GLenum {
     RGBA = GL_COMPRESSED_RGBA,
 
     /**
-     * RGTC compressed red channel, normalized unsigned. **Available only for
-     * 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red channel, normalized unsigned. Equivalent to the old
+     * @def_gl{COMPRESSED_LUMINANCE_LATC1_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red channel
+     * instead of all three. **Available only on 2D, 2D array, cube map and
+     * cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.
@@ -721,8 +724,11 @@ enum class CompressedPixelFormat: GLenum {
     RedRgtc1 = GL_COMPRESSED_RED_RGTC1,
 
     /**
-     * RGTC compressed red and green channel, normalized unsigned. **Available
-     * only for 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red and green channel, normalized unsigned. Equivalent
+     * to the old @def_gl{COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red and
+     * green channel instead of all four. **Available only on 2D, 2D array,
+     * cube map and cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.
@@ -730,8 +736,11 @@ enum class CompressedPixelFormat: GLenum {
     RGRgtc2 = GL_COMPRESSED_RG_RGTC2,
 
     /**
-     * RGTC compressed red channel, normalized signed. **Available only for 2D,
-     * 2D array, cube map and cube map array textures.**
+     * RGTC compressed red channel, normalized signed. Equivalent to the old
+     * @def_gl{COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red channel
+     * instead of all three. **Available only on 2D, 2D array, cube map and
+     * cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.
@@ -739,8 +748,11 @@ enum class CompressedPixelFormat: GLenum {
     SignedRedRgtc1 = GL_COMPRESSED_SIGNED_RED_RGTC1,
 
     /**
-     * RGTC compressed red and green channel, normalized signed. **Available
-     * only for 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red and green channel, normalized signed. Equivalent
+     * to the old @def_gl{COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red and
+     * green channel instead of all four. **Available only on 2D, 2D array,
+     * cube map and cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.

src/Magnum/GL/TextureFormat.h

@@ -1014,8 +1014,11 @@ enum class TextureFormat: GLenum {
     CompressedRGBA = GL_COMPRESSED_RGBA,
 
     /**
-     * RGTC compressed red channel, normalized unsigned. **Available only on
-     * 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red channel, normalized unsigned. Equivalent to the old
+     * @def_gl{COMPRESSED_LUMINANCE_LATC1_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red channel
+     * instead of all three. **Available only on 2D, 2D array, cube map and
+     * cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl Generic texture compression is not available in OpenGL ES
      *      or WebGL.
@@ -1023,8 +1026,11 @@ enum class TextureFormat: GLenum {
     CompressedRedRgtc1 = GL_COMPRESSED_RED_RGTC1,
 
     /**
-     * RGTC compressed red and green channel, normalized unsigned. **Available
-     * only on 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red and green channel, normalized unsigned. Equivalent
+     * to the old @def_gl{COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red and
+     * green channel instead of all four. **Available only on 2D, 2D array,
+     * cube map and cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.
@@ -1032,8 +1038,11 @@ enum class TextureFormat: GLenum {
     CompressedRGRgtc2 = GL_COMPRESSED_RG_RGTC2,
 
     /**
-     * RGTC compressed red channel, normalized signed. **Available only on 2D,
-     * 2D array, cube map and cube map array textures.**
+     * RGTC compressed red channel, normalized signed. Equivalent to the old
+     * @def_gl{COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red channel
+     * instead of all three. **Available only on 2D, 2D array, cube map and
+     * cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.
@@ -1041,8 +1050,11 @@ enum class TextureFormat: GLenum {
     CompressedSignedRedRgtc1 = GL_COMPRESSED_SIGNED_RED_RGTC1,
 
     /**
-     * RGTC compressed red and green channel, normalized signed. **Available
-     * only on 2D, 2D array, cube map and cube map array textures.**
+     * RGTC compressed red and green channel, normalized signed. Equivalent
+     * to the old @def_gl{COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT} from
+     * @gl_extension{EXT,texture_compression_latc}, only using the red and
+     * green channel instead of all four. **Available only on 2D, 2D array,
+     * cube map and cube map array textures.**
      * @requires_gl30 Extension @gl_extension{EXT,texture_compression_rgtc}
      * @requires_gl RGTC texture compression is not available in OpenGL ES or
      *      WebGL.