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adjust_colors() function replaces old _mesa_chan_to_float_span() function.

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This commit is contained in:
Brian Paul
2006-10-12 23:48:57 +00:00
parent 0bfc56d7d3
commit e392c92250
1 changed files with 45 additions and 26 deletions
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71
src/mesa/swrast/s_readpix.c
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@@ -262,6 +262,41 @@ fast_read_rgba_pixels( GLcontext *ctx,
}
/**
* When we're using a low-precision color buffer (like 16-bit 5/6/5)
* we have to adjust our color values a bit to pass conformance.
* The problem is when a 5 or 6-bit color value is convert to an 8-bit
* value and then a floating point value, the floating point values don't
* increment uniformly as the 5 or 6-bit value is incremented.
*
* This function adjusts floating point values to compensate.
*/
static void
adjust_colors(GLcontext *ctx, GLuint n, GLfloat rgba[][4])
{
const GLuint rShift = 8 - ctx->Visual.redBits;
const GLuint gShift = 8 - ctx->Visual.greenBits;
const GLuint bShift = 8 - ctx->Visual.blueBits;
const GLfloat rScale = 1.0F / (GLfloat) ((1 << ctx->Visual.redBits ) - 1);
const GLfloat gScale = 1.0F / (GLfloat) ((1 << ctx->Visual.greenBits) - 1);
const GLfloat bScale = 1.0F / (GLfloat) ((1 << ctx->Visual.blueBits ) - 1);
GLuint i;
for (i = 0; i < n; i++) {
GLint r, g, b;
/* convert float back to ubyte */
CLAMPED_FLOAT_TO_UBYTE(r, rgba[i][RCOMP]);
CLAMPED_FLOAT_TO_UBYTE(g, rgba[i][GCOMP]);
CLAMPED_FLOAT_TO_UBYTE(b, rgba[i][BCOMP]);
/* using only the N most significant bits of the ubyte value, convert to
* float in [0,1].
*/
rgba[i][RCOMP] = (GLfloat) (r >> rShift) * rScale;
rgba[i][GCOMP] = (GLfloat) (g >> gShift) * gScale;
rgba[i][BCOMP] = (GLfloat) (b >> bShift) * bScale;
}
}
/*
* Read R, G, B, A, RGB, L, or LA pixels.
@@ -376,33 +411,17 @@ read_rgba_pixels( GLcontext *ctx,
_mesa_map_ci_to_rgba(ctx, width, index, rgba);
}
/* apply fudge factor for shallow color buffers */
if (fb->Visual.redBits < 8 ||
fb->Visual.greenBits < 8 ||
fb->Visual.blueBits < 8) {
adjust_colors(ctx, width, rgba);
}
/* pack the row of RGBA pixels into user's buffer */
#if 0
/* XXX may need to rejuvinate this code if we get conformance
* falures on 16bpp displays (i.e. 5/6/5).
*/
if (fb->Visual.redBits < CHAN_BITS ||
fb->Visual.greenBits < CHAN_BITS ||
fb->Visual.blueBits < CHAN_BITS) {
/* Requantize the color values into floating point and go from
* there. This fixes conformance failures with 5/6/5 color
* buffers, for example.
*/
GLfloat rgbaf[MAX_WIDTH][4];
_mesa_chan_to_float_span(ctx, width,
(CONST GLchan (*)[4]) rgba, rgbaf);
_mesa_pack_rgba_span_float(ctx, width,
(CONST GLfloat (*)[4]) rgbaf,
format, type, dst, packing,
ctx->_ImageTransferState);
}
else
#endif
{
_mesa_pack_rgba_span_float(ctx, width, (CONST GLfloat (*)[4]) rgba,
format, type, dst,
packing, ctx->_ImageTransferState);
}
_mesa_pack_rgba_span_float(ctx, width, (CONST GLfloat (*)[4]) rgba,
format, type, dst,
packing, ctx->_ImageTransferState);
dst += dstStride;
}