From 92234b1b2aaf6ba68e786498806cefd4bd99dabc Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Mon, 24 Mar 2014 01:16:57 -0700 Subject: [PATCH] mesa: Introduce a _mesa_format_has_color_component() helper. When considering color write masks, we often want to know whether an RGBA component actually contains any meaningful data. This function provides an easy way to answer that question, and handles luminance, intensity, and alpha formats correctly. Signed-off-by: Kenneth Graunke Reviewed-by: Brian Paul Reviewed-by: Eric Anholt Reviewed-by: Ian Romanick Tested-by: Dylan Baker --- src/mesa/main/formats.c | 29 +++++++++++++++++++++++++++++ src/mesa/main/formats.h | 4 ++++ 2 files changed, 33 insertions(+) diff --git a/src/mesa/main/formats.c b/src/mesa/main/formats.c index e74625f2369..fb2501c69a2 100644 --- a/src/mesa/main/formats.c +++ b/src/mesa/main/formats.c @@ -2206,6 +2206,35 @@ _mesa_format_num_components(mesa_format format) } +/** + * Returns true if a color format has data stored in the R/G/B/A channels, + * given an index from 0 to 3. + */ +bool +_mesa_format_has_color_component(mesa_format format, int component) +{ + const struct gl_format_info *info = _mesa_get_format_info(format); + + assert(info->BaseFormat != GL_DEPTH_COMPONENT && + info->BaseFormat != GL_DEPTH_STENCIL && + info->BaseFormat != GL_STENCIL_INDEX); + + switch (component) { + case 0: + return (info->RedBits + info->IntensityBits + info->LuminanceBits) > 0; + case 1: + return (info->GreenBits + info->IntensityBits + info->LuminanceBits) > 0; + case 2: + return (info->BlueBits + info->IntensityBits + info->LuminanceBits) > 0; + case 3: + return (info->AlphaBits + info->IntensityBits) > 0; + default: + assert(!"Invalid color component: must be 0..3"); + return false; + } +} + + /** * Return number of bytes needed to store an image of the given size * in the given format. diff --git a/src/mesa/main/formats.h b/src/mesa/main/formats.h index 3079f0356cf..89bd0219eab 100644 --- a/src/mesa/main/formats.h +++ b/src/mesa/main/formats.h @@ -34,6 +34,7 @@ #include +#include #ifdef __cplusplus @@ -474,6 +475,9 @@ _mesa_get_uncompressed_format(mesa_format format); extern GLuint _mesa_format_num_components(mesa_format format); +extern bool +_mesa_format_has_color_component(mesa_format format, int component); + GLboolean _mesa_format_matches_format_and_type(mesa_format mesa_format, GLenum format, GLenum type, -- 2.30.2