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mesa: add _mesa_rebase_rgba_float/uint() functions

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These will be used by glReadPixels() and glGetTexImage() to fix issues
with reading GL_LUMINANCE and other formats.

NOTE: This is a candidate for the 8.0 branch.

Reviewed-by: José Fonseca <jfonseca@vmware.com>
This commit is contained in:
Brian Paul 2012-02-29 20:55:49 -07:00
parent be5f27a84d
commit 774c402765
2 changed files with 98 additions and 0 deletions
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91
src/mesa/main/pack.c
View file

@ -5250,3 +5250,94 @@ _mesa_unpack_image( GLuint dimensions,
}
}
/**
* If we unpack colors from a luminance surface, we'll get pixel colors
* such as (l, l, l, a).
* When we call _mesa_pack_rgba_span_float(format=GL_LUMINANCE), that
* function will compute L=R+G+B before packing. The net effect is we'll
* accidentally store luminance values = 3*l.
* This function compensates for that by converting (aka rebasing) (l,l,l,a)
* to be (l,0,0,a).
* It's a similar story for other formats such as LUMINANCE_ALPHA, ALPHA
* and INTENSITY.
*
* Finally, we also need to do this when the actual surface format does
* not match the logical surface format. For example, suppose the user
* requests a GL_LUMINANCE texture but the driver stores it as RGBA.
* Again, we'll get pixel values like (l,l,l,a).
*/
void
_mesa_rebase_rgba_float(GLuint n, GLfloat rgba[][4], GLenum baseFormat)
{
GLuint i;
switch (baseFormat) {
case GL_ALPHA:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = 0.0F;
rgba[i][GCOMP] = 0.0F;
rgba[i][BCOMP] = 0.0F;
}
break;
case GL_INTENSITY:
/* fall-through */
case GL_LUMINANCE:
for (i = 0; i < n; i++) {
rgba[i][GCOMP] = 0.0F;
rgba[i][BCOMP] = 0.0F;
rgba[i][ACOMP] = 1.0F;
}
break;
case GL_LUMINANCE_ALPHA:
for (i = 0; i < n; i++) {
rgba[i][GCOMP] = 0.0F;
rgba[i][BCOMP] = 0.0F;
}
break;
default:
/* no-op */
;
}
}
/**
* As above, but GLuint components.
*/
void
_mesa_rebase_rgba_uint(GLuint n, GLuint rgba[][4], GLenum baseFormat)
{
GLuint i;
switch (baseFormat) {
case GL_ALPHA:
for (i = 0; i < n; i++) {
rgba[i][RCOMP] = 0;
rgba[i][GCOMP] = 0;
rgba[i][BCOMP] = 0;
}
break;
case GL_INTENSITY:
/* fall-through */
case GL_LUMINANCE:
for (i = 0; i < n; i++) {
rgba[i][GCOMP] = 0;
rgba[i][BCOMP] = 0;
rgba[i][ACOMP] = 1;
}
break;
case GL_LUMINANCE_ALPHA:
for (i = 0; i < n; i++) {
rgba[i][GCOMP] = 0;
rgba[i][BCOMP] = 0;
}
break;
default:
/* no-op */
;
}
}

7
src/mesa/main/pack.h
View file

@ -149,4 +149,11 @@ _mesa_pack_rgba_span_int(struct gl_context *ctx, GLuint n, GLuint rgba[][4],
GLenum dstFormat, GLenum dstType,
GLvoid *dstAddr);
extern void
_mesa_rebase_rgba_float(GLuint n, GLfloat rgba[][4], GLenum baseFormat);
extern void
_mesa_rebase_rgba_uint(GLuint n, GLuint rgba[][4], GLenum baseFormat);
#endif