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tnl: Add support for datatype GL_FIXED in vertex arrays

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Before populating the vertex buffer attribute pointer (VB->AttribPtr[]),
convert vertex data in GL_FIXED format to GL_FLOAT.

Fixes bug: http://bugs.freedesktop.org/show_bug.cgi?id=34047

NOTE: This is a candidate for the 7.9 and 7.10 branches.
(cherry picked from commit a231ac23f4)
This commit is contained in:
Chad Versace 2011-02-15 15:30:05 -08:00 • committed by Ian Romanick
parent e160c815c2
commit 8a27f9845b
1 changed files with 40 additions and 0 deletions
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40
src/mesa/tnl/t_draw.c
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@ -125,6 +125,43 @@ convert_half_to_float(const struct gl_client_array *input,
}
}
/**
* \brief Convert fixed-point to floating-point.
*
* In OpenGL, a fixed-point number is a "signed 2's complement 16.16 scaled
* integer" (Table 2.2 of the OpenGL ES 2.0 spec).
*
* If the buffer has the \c normalized flag set, the formula
* \code normalize(x) := (2*x + 1) / (2^16 - 1) \endcode
* is used to map the fixed-point numbers into the range [-1, 1].
*/
static void
convert_fixed_to_float(const struct gl_client_array *input,
const GLubyte *ptr, GLfloat *fptr,
GLuint count)
{
GLuint i, j;
const GLint size = input->Size;
if (input->Normalized) {
for (i = 0; i < count; ++i) {
const GLfixed *in = (GLfixed *) ptr;
for (j = 0; j < size; ++j) {
*fptr++ = (GLfloat) (2 * in[j] + 1) / (GLfloat) ((1 << 16) - 1);
}
ptr += input->StrideB;
}
} else {
for (i = 0; i < count; ++i) {
const GLfixed *in = (GLfixed *) ptr;
for (j = 0; j < size; ++j) {
*fptr++ = in[j] / (GLfloat) (1 << 16);
}
ptr += input->StrideB;
}
}
}
/* Adjust pointer to point at first requested element, convert to
* floating point, populate VB->AttribPtr[].
*/
@ -174,6 +211,9 @@ static void _tnl_import_array( struct gl_context *ctx,
case GL_HALF_FLOAT:
convert_half_to_float(input, ptr, fptr, count, sz);
break;
case GL_FIXED:
convert_fixed_to_float(input, ptr, fptr, count);
break;
default:
assert(0);
break;