From cb535550588852175f22fd17ad080bc213021881 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Sun, 10 Sep 2006 17:42:57 +0000 Subject: Redefine the BYTE_TO_FLOAT() and SHORT_TO_FLOAT() macros to avoid problems converting 0 to exactly 0.0 This goes against the OpenGL spec (see table 2.6) but solves problems when doing byte -> float -> ubyte conversion for particular texture formats. --- src/mesa/main/image.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) (limited to 'src/mesa') diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c index a5074efe17..b46e323db2 100644 --- a/src/mesa/main/image.c +++ b/src/mesa/main/image.c @@ -39,6 +39,22 @@ #include "pixel.h" +/** + * NOTE: + * Normally, BYTE_TO_FLOAT(0) returns 0.00392 That causes problems when + * we later convert the float to a packed integer value (such as for + * GL_RGB5_A1) because we'll wind up with a non-zero value. + * + * We redefine the macros here so zero is handled correctly. + */ +#undef BYTE_TO_FLOAT +#define BYTE_TO_FLOAT(B) ((B) == 0 ? 0.0F : ((2.0F * (B) + 1.0F) * (1.0F/255.0F))) + +#undef SHORT_TO_FLOAT +#define SHORT_TO_FLOAT(S) ((S) == 0 ? 0.0F : ((2.0F * (S) + 1.0F) * (1.0F/65535.0F))) + + + /** Compute ceiling of integer quotient of A divided by B. */ #define CEILING( A, B ) ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 ) @@ -398,10 +414,6 @@ _mesa_is_legal_format_and_type( GLcontext *ctx, GLenum format, GLenum type ) case GL_INT: case GL_UNSIGNED_INT: case GL_FLOAT: - case GL_UNSIGNED_BYTE_3_3_2: - case GL_UNSIGNED_BYTE_2_3_3_REV: - case GL_UNSIGNED_SHORT_5_6_5: - case GL_UNSIGNED_SHORT_5_6_5_REV: return GL_TRUE; case GL_HALF_FLOAT_ARB: return ctx->Extensions.ARB_half_float_pixel; @@ -417,6 +429,10 @@ _mesa_is_legal_format_and_type( GLcontext *ctx, GLenum format, GLenum type ) case GL_INT: case GL_UNSIGNED_INT: case GL_FLOAT: + case GL_UNSIGNED_BYTE_3_3_2: + case GL_UNSIGNED_BYTE_2_3_3_REV: + case GL_UNSIGNED_SHORT_5_6_5: + case GL_UNSIGNED_SHORT_5_6_5_REV: return GL_TRUE; case GL_HALF_FLOAT_ARB: return ctx->Extensions.ARB_half_float_pixel; -- cgit v1.2.3