diff options
Diffstat (limited to 'mesalib/src/mesa/main/texcompress.c')
| -rw-r--r-- | mesalib/src/mesa/main/texcompress.c | 205 |
1 files changed, 178 insertions, 27 deletions
diff --git a/mesalib/src/mesa/main/texcompress.c b/mesalib/src/mesa/main/texcompress.c index d820ae927..42bd1eee5 100644 --- a/mesalib/src/mesa/main/texcompress.c +++ b/mesalib/src/mesa/main/texcompress.c @@ -40,19 +40,192 @@ /** + * Get the GL base format of a specified GL compressed texture format + * + * From page 232 of the OpenGL 3.3 (Compatiblity Profile) spec: + * + * "Compressed Internal Format Base Internal Format Type + * --------------------------- -------------------- --------- + * COMPRESSED_ALPHA ALPHA Generic + * COMPRESSED_LUMINANCE LUMINANCE Generic + * COMPRESSED_LUMINANCE_ALPHA LUMINANCE_ALPHA Generic + * COMPRESSED_INTENSITY INTENSITY Generic + * COMPRESSED_RED RED Generic + * COMPRESSED_RG RG Generic + * COMPRESSED_RGB RGB Generic + * COMPRESSED_RGBA RGBA Generic + * COMPRESSED_SRGB RGB Generic + * COMPRESSED_SRGB_ALPHA RGBA Generic + * COMPRESSED_SLUMINANCE LUMINANCE Generic + * COMPRESSED_SLUMINANCE_ALPHA LUMINANCE_ALPHA Generic + * COMPRESSED_RED_RGTC1 RED Specific + * COMPRESSED_SIGNED_RED_RGTC1 RED Specific + * COMPRESSED_RG_RGTC2 RG Specific + * COMPRESSED_SIGNED_RG_RGTC2 RG Specific" + * + * \return + * The base format of \c format if \c format is a compressed format (either + * generic or specific. Otherwise 0 is returned. + */ +GLenum +_mesa_gl_compressed_format_base_format(GLenum format) +{ + switch (format) { + case GL_COMPRESSED_RED: + case GL_COMPRESSED_RED_RGTC1: + case GL_COMPRESSED_SIGNED_RED_RGTC1: + return GL_RED; + + case GL_COMPRESSED_RG: + case GL_COMPRESSED_RG_RGTC2: + case GL_COMPRESSED_SIGNED_RG_RGTC2: + return GL_RG; + + case GL_COMPRESSED_RGB: + case GL_COMPRESSED_SRGB: + case GL_COMPRESSED_RGB_S3TC_DXT1_EXT: + case GL_COMPRESSED_RGB_FXT1_3DFX: + case GL_COMPRESSED_SRGB_S3TC_DXT1_EXT: + return GL_RGB; + + case GL_COMPRESSED_RGBA: + case GL_COMPRESSED_SRGB_ALPHA: + case GL_COMPRESSED_RGBA_BPTC_UNORM_ARB: + case GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM_ARB: + case GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT_ARB: + case GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT_ARB: + case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT: + case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT: + case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT: + case GL_COMPRESSED_RGBA_FXT1_3DFX: + case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT: + case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT: + case GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT: + return GL_RGBA; + + case GL_COMPRESSED_ALPHA: + return GL_ALPHA; + + case GL_COMPRESSED_LUMINANCE: + case GL_COMPRESSED_SLUMINANCE: + case GL_COMPRESSED_LUMINANCE_LATC1_EXT: + case GL_COMPRESSED_SIGNED_LUMINANCE_LATC1_EXT: + return GL_LUMINANCE; + + case GL_COMPRESSED_LUMINANCE_ALPHA: + case GL_COMPRESSED_SLUMINANCE_ALPHA: + case GL_COMPRESSED_LUMINANCE_ALPHA_LATC2_EXT: + case GL_COMPRESSED_SIGNED_LUMINANCE_ALPHA_LATC2_EXT: + case GL_COMPRESSED_LUMINANCE_ALPHA_3DC_ATI: + return GL_LUMINANCE_ALPHA; + + case GL_COMPRESSED_INTENSITY: + return GL_INTENSITY; + + default: + return 0; + } +} + +/** * Return list of (and count of) all specific texture compression * formats that are supported. * + * Some formats are \b not returned by this function. The + * \c GL_COMPRESSED_TEXTURE_FORMATS query only returns formats that are + * "suitable for general-purpose usage." All texture compression extensions + * have taken this to mean either linear RGB or linear RGBA. + * + * The GL_ARB_texture_compress_rgtc spec says: + * + * "19) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and + * GL_COMPRESSED_TEXTURE_FORMATS queries return the RGTC formats? + * + * RESOLVED: No. + * + * The OpenGL 2.1 specification says "The only values returned + * by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those + * corresponding to formats suitable for general-purpose usage. + * The renderer will not enumerate formats with restrictions that + * need to be specifically understood prior to use." + * + * Compressed textures with just red or red-green components are + * not general-purpose so should not be returned by these queries + * because they have restrictions. + * + * Applications that seek to use the RGTC formats should do so + * by looking for this extension's name in the string returned by + * glGetString(GL_EXTENSIONS) rather than + * what GL_NUM_COMPRESSED_TEXTURE_FORMATS and + * GL_COMPRESSED_TEXTURE_FORMATS return." + * + * There is nearly identical wording in the GL_EXT_texture_compression_rgtc + * spec. + * + * The GL_EXT_texture_rRGB spec says: + * + * "22) Should the new COMPRESSED_SRGB_* formats be listed in an + * implementation's GL_COMPRESSED_TEXTURE_FORMATS list? + * + * RESOLVED: No. Section 3.8.1 says formats listed by + * GL_COMPRESSED_TEXTURE_FORMATS are "suitable for general-purpose + * usage." The non-linear distribution of red, green, and + * blue for these sRGB compressed formats makes them not really + * general-purpose." + * + * The GL_EXT_texture_compression_latc spec says: + * + * "16) Should the GL_NUM_COMPRESSED_TEXTURE_FORMATS and + * GL_COMPRESSED_TEXTURE_FORMATS queries return the LATC formats? + * + * RESOLVED: No. + * + * The OpenGL 2.1 specification says "The only values returned + * by this query [GL_COMPRESSED_TEXTURE_FORMATS"] are those + * corresponding to formats suitable for general-purpose usage. + * The renderer will not enumerate formats with restrictions that + * need to be specifically understood prior to use." + * + * Historically, OpenGL implementation have advertised the RGB and + * RGBA versions of the S3TC extensions compressed format tokens + * through this mechanism. + * + * The specification is not sufficiently clear about what "suitable + * for general-purpose usage" means. Historically that seems to mean + * unsigned RGB or unsigned RGBA. The DXT1 format supporting alpha + * (GL_COMPRESSED_RGBA_S3TC_DXT1_EXT) is not exposed in the list (at + * least for NVIDIA drivers) because the alpha is always 1.0 expect + * when it is 0.0 when RGB is required to be black. NVIDIA's even + * limits itself to true linear RGB or RGBA formats, specifically + * not including EXT_texture_sRGB's sRGB S3TC compressed formats. + * + * Adding luminance and luminance-alpha texture formats (and + * certainly signed versions of luminance and luminance-alpha + * formats!) invites potential comptaibility problems with old + * applications using this mechanism since old applications are + * unlikely to expect non-RGB or non-RGBA formats to be advertised + * through this mechanism. However no specific misinteractions + * with old applications is known. + * + * Applications that seek to use the LATC formats should do so + * by looking for this extension's name in the string returned by + * glGetString(GL_EXTENSIONS) rather than + * what GL_NUM_COMPRESSED_TEXTURE_FORMATS and + * GL_COMPRESSED_TEXTURE_FORMATS return." + * + * There is no formal spec for GL_ATI_texture_compression_3dc. Since the + * formats added by this extension are luminance-alpha formats, it is + * reasonable to expect them to follow the same rules as + * GL_EXT_texture_compression_latc. At the very least, Catalyst 11.6 does not + * expose the 3dc formats through this mechanism. + * * \param ctx the GL context * \param formats the resulting format list (may be NULL). - * \param all if true return all formats, even those with some kind - * of restrictions/limitations (See GL_ARB_texture_compression - * spec for more info). * * \return number of formats. */ GLuint -_mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats, GLboolean all) +_mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats) { GLuint n = 0; if (ctx->Extensions.TDFX_texture_compression_FXT1) { @@ -64,24 +237,15 @@ _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats, GLboolean a n += 2; } } - /* don't return RGTC - ARB_texture_compression_rgtc query 19 */ + if (ctx->Extensions.EXT_texture_compression_s3tc) { if (formats) { formats[n++] = GL_COMPRESSED_RGB_S3TC_DXT1_EXT; - /* This format has some restrictions/limitations and so should - * not be returned via the GL_COMPRESSED_TEXTURE_FORMATS query. - * Specifically, all transparent pixels become black. NVIDIA - * omits this format too. - */ - if (all) - formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT1_EXT; formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT3_EXT; formats[n++] = GL_COMPRESSED_RGBA_S3TC_DXT5_EXT; } else { n += 3; - if (all) - n += 1; } } if (ctx->Extensions.S3_s3tc) { @@ -95,19 +259,6 @@ _mesa_get_compressed_formats(struct gl_context *ctx, GLint *formats, GLboolean a n += 4; } } -#if FEATURE_EXT_texture_sRGB - if (ctx->Extensions.EXT_texture_sRGB) { - if (formats) { - formats[n++] = GL_COMPRESSED_SRGB_S3TC_DXT1_EXT; - formats[n++] = GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT; - formats[n++] = GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT; - formats[n++] = GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT; - } - else { - n += 4; - } - } -#endif /* FEATURE_EXT_texture_sRGB */ return n; #if FEATURE_ES1 || FEATURE_ES2 |