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windows-nt/Source/XPSP1/NT/multimedia/opengl/server/soft/so_texfi.c

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2020-09-26 03:20:57 -05:00
/*
** Copyright 1991,1992, Silicon Graphics, Inc.
** All Rights Reserved.
**
** This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;
** the contents of this file may not be disclosed to third parties, copied or
** duplicated in any form, in whole or in part, without the prior written
** permission of Silicon Graphics, Inc.
**
** RESTRICTED RIGHTS LEGEND:
** Use, duplication or disclosure by the Government is subject to restrictions
** as set forth in subdivision (c)(1)(ii) of the Rights in Technical Data
** and Computer Software clause at DFARS 252.227-7013, and/or in similar or
** successor clauses in the FAR, DOD or NASA FAR Supplement. Unpublished -
** rights reserved under the Copyright Laws of the United States.
**
*/
#include "precomp.h"
#pragma hdrstop
#include <namesint.h>
#include <math.h>
/*
** Some math routines that are optimized in assembly
*/
#define __GL_FRAC(f) ((f) - __GL_FAST_FLOORF(f))
/************************************************************************/
// Repeats the given float value in float [0, scale) and converts to
// int. The repeat count is an integer which is a power of two
#define REPEAT_SCALED_VAL(val, scale, repeat) \
(__GL_FLOAT_GEZ(val) ? (FTOL((val) * (scale)) & ((repeat)-1)) : \
((repeat)-1)-(FTOL(-(val) * (scale)) & ((repeat)-1)))
// Clamps the given float value to float [0, scale) and converts to int
#define CLAMP_SCALED_VAL(val, scale) \
(__GL_FLOAT_LEZ(val) ? 0 : \
__GL_FLOAT_COMPARE_PONE(val, >=) ? (FTOL(scale)-1) : \
FTOL((val) * (scale)))
/*
** Return texel nearest the s coordinate. s is converted to u
** implicitly during this step.
*/
void FASTCALL __glNearestFilter1(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
GLint col;
__GLfloat w2f;
CHOP_ROUND_ON();
#ifdef __GL_LINT
gc = gc;
color = color;
t = t;
#endif
/* Find texel index */
w2f = lp->width2f;
if (tex->params.sWrapMode == GL_REPEAT) {
col = REPEAT_SCALED_VAL(s, w2f, lp->width2);
} else {
col = CLAMP_SCALED_VAL(s, w2f);
}
CHOP_ROUND_OFF();
/* Lookup texel */
(*lp->extract)(lp, tex, 0, col, result);
}
/*
** Return texel nearest the s&t coordinates. s&t are converted to u&v
** implicitly during this step.
*/
void FASTCALL __glNearestFilter2(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
GLint row, col;
__GLfloat w2f, h2f;
CHOP_ROUND_ON();
#ifdef __GL_LINT
gc = gc;
color = color;
#endif
/* Find texel column address */
w2f = lp->width2f;
if (tex->params.sWrapMode == GL_REPEAT) {
col = REPEAT_SCALED_VAL(s, w2f, lp->width2);
} else {
col = CLAMP_SCALED_VAL(s, w2f);
}
/* Find texel row address */
h2f = lp->height2f;
if (tex->params.tWrapMode == GL_REPEAT) {
row = REPEAT_SCALED_VAL(t, h2f, lp->height2);
} else {
row = CLAMP_SCALED_VAL(t, h2f);
}
CHOP_ROUND_OFF();
/* Lookup texel */
(*lp->extract)(lp, tex, row, col, result);
}
/*
** Return texel which is a linear combination of texels near s.
*/
void FASTCALL __glLinearFilter1(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
__GLfloat u, alpha, omalpha, w2f;
GLint col0, col1;
__GLtexel t0, t1;
#ifdef __GL_LINT
color = color;
t = t;
#endif
/* Find col0 and col1 */
w2f = lp->width2f;
u = s * w2f;
if (tex->params.sWrapMode == GL_REPEAT) {
GLint w2mask = lp->width2 - 1;
u -= __glHalf;
col0 = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col0; // Get fractional part
col0 &= w2mask;
col1 = (col0 + 1) & w2mask;
} else {
if (u < __glZero) u = __glZero;
else if (u > w2f) u = w2f;
u -= __glHalf;
col0 = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col0; // Get fractional part
col1 = col0 + 1;
}
/* Calculate the final texel value as a combination of the two texels */
(*lp->extract)(lp, tex, 0, col0, &t0);
(*lp->extract)(lp, tex, 0, col1, &t1);
omalpha = __glOne - alpha;
switch (lp->baseFormat) {
case GL_LUMINANCE_ALPHA:
result->alpha = omalpha * t0.alpha + alpha * t1.alpha;
/* FALLTHROUGH */
case GL_LUMINANCE:
result->luminance = omalpha * t0.luminance + alpha * t1.luminance;
break;
case GL_RGBA:
result->alpha = omalpha * t0.alpha + alpha * t1.alpha;
/* FALLTHROUGH */
case GL_RGB:
result->r = omalpha * t0.r + alpha * t1.r;
result->g = omalpha * t0.g + alpha * t1.g;
result->b = omalpha * t0.b + alpha * t1.b;
break;
case GL_ALPHA:
result->alpha = omalpha * t0.alpha + alpha * t1.alpha;
break;
case GL_INTENSITY:
result->intensity = omalpha * t0.intensity + alpha * t1.intensity;
break;
}
}
/*
** Return texel which is a linear combination of texels near s&t.
*/
void FASTCALL __glLinearFilter2(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
__GLfloat u, v, alpha, beta, half, w2f, h2f;
GLint col0, row0, col1, row1;
__GLtexel t00, t01, t10, t11;
__GLfloat omalpha, ombeta, m00, m01, m10, m11;
#ifdef __GL_LINT
color = color;
#endif
/* Find col0, col1 */
w2f = lp->width2f;
u = s * w2f;
half = __glHalf;
if (tex->params.sWrapMode == GL_REPEAT) {
GLint w2mask = lp->width2 - 1;
u -= half;
col0 = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col0; // Get fractional part
col0 &= w2mask;
col1 = (col0 + 1) & w2mask;
} else {
if (u < __glZero) u = __glZero;
else if (u > w2f) u = w2f;
u -= half;
col0 = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col0; // Get fractional part
col1 = col0 + 1;
}
/* Find row0, row1 */
h2f = lp->height2f;
v = t * h2f;
if (tex->params.tWrapMode == GL_REPEAT) {
GLint h2mask = lp->height2 - 1;
v -= half;
row0 = (__GL_FAST_FLOORF_I(v));
beta = v - (__GLfloat) row0; // Get fractional part
row0 &= h2mask;
row1 = (row0 + 1) & h2mask;
} else {
if (v < __glZero) v = __glZero;
else if (v > h2f) v = h2f;
v -= half;
row0 = __GL_FAST_FLOORF_I(v);
beta = v - (__GLfloat) row0; // Get fractional part
row1 = row0 + 1;
}
/* Calculate the final texel value as a combination of the square chosen */
(*lp->extract)(lp, tex, row0, col0, &t00);
(*lp->extract)(lp, tex, row0, col1, &t10);
(*lp->extract)(lp, tex, row1, col0, &t01);
(*lp->extract)(lp, tex, row1, col1, &t11);
omalpha = __glOne - alpha;
ombeta = __glOne - beta;
m00 = omalpha * ombeta;
m10 = alpha * ombeta;
m01 = omalpha * beta;
m11 = alpha * beta;
switch (lp->baseFormat) {
case GL_LUMINANCE_ALPHA:
/* FALLTHROUGH */
result->alpha = m00*t00.alpha + m10*t10.alpha + m01*t01.alpha
+ m11*t11.alpha;
case GL_LUMINANCE:
result->luminance = m00*t00.luminance + m10*t10.luminance
+ m01*t01.luminance + m11*t11.luminance;
break;
case GL_RGBA:
/* FALLTHROUGH */
result->alpha = m00*t00.alpha + m10*t10.alpha + m01*t01.alpha
+ m11*t11.alpha;
case GL_RGB:
result->r = m00*t00.r + m10*t10.r + m01*t01.r + m11*t11.r;
result->g = m00*t00.g + m10*t10.g + m01*t01.g + m11*t11.g;
result->b = m00*t00.b + m10*t10.b + m01*t01.b + m11*t11.b;
break;
case GL_ALPHA:
result->alpha = m00*t00.alpha + m10*t10.alpha + m01*t01.alpha
+ m11*t11.alpha;
break;
case GL_INTENSITY:
result->intensity = m00*t00.intensity + m10*t10.intensity
+ m01*t01.intensity + m11*t11.intensity;
break;
}
}
// Macros to convert unsigned byte rgb{a} to float
#define __glBGRByteToFloat( fdst, bsrc ) \
(fdst)->b = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(fdst)->g = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(fdst)->r = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(bsrc)++;
#define __glBGRAByteToFloat( fdst, bsrc ) \
(fdst)->b = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(fdst)->g = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(fdst)->r = __GL_UB_TO_FLOAT( *(bsrc)++ ); \
(fdst)->a = __GL_UB_TO_FLOAT( *(bsrc)++ );
void FASTCALL __glLinearFilter2_BGR8Repeat(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
__GLfloat u, v, alpha, beta, half;
GLint col, row, rowLen;
__GLcolor t00, t01, t10, t11;
__GLfloat omalpha, ombeta, m00, m01, m10, m11;
GLint width2m1, height2m1;
GLubyte *image, *pData;
#ifdef __GL_LINT
color = color;
#endif
half = __glHalf;
width2m1 = lp->width2 - 1;
height2m1 = lp->height2 - 1;
/* Find col, compute alpha */
u = (s * lp->width2f) - half;
col = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col; // Get fractional part
col &= width2m1;
/* Find row, compute beta */
v = (t * lp->height2f) - half;
row = __GL_FAST_FLOORF_I(v);
beta = v - (__GLfloat) row; // Get fractional part
row &= height2m1;
// Extract first texel at row, col
pData = image =
(GLubyte *)lp->buffer + (((row << lp->widthLog2) + col) << 2);
__glBGRByteToFloat( &t00, pData );
// Extract remaining texels
rowLen = lp->width2 << 2; // row length in bytes
if( (row < height2m1) &&
(col < width2m1) )
{
// Most common case - the texels are a compact block of 4
// Next texel along row
__glBGRByteToFloat( &t10, pData );
// Up to next row...
pData += (rowLen-8);
__glBGRByteToFloat( &t01, pData );
__glBGRByteToFloat( &t11, pData );
} else {
// Exceptional case : one or both of row, col are on edge
GLint rowInc, colInc; // increments in bytes
// Calc increments to next texel along row/col
if( col < width2m1 )
rowInc = 4;
else
// increment to left edge
rowInc = -(rowLen - 4);
if( row < height2m1 )
// increment by row length
colInc = rowLen;
else
// increment to lower edge
colInc = - height2m1 * rowLen;
// Next texel along row
pData = image + rowInc;
__glBGRByteToFloat( &t10, pData );
// Second row, first texel
pData = image + colInc;
__glBGRByteToFloat( &t01, pData );
// Next texel along row
pData += (rowInc - 4);
__glBGRByteToFloat( &t11, pData );
}
omalpha = __glOne - alpha;
ombeta = __glOne - beta;
m00 = omalpha * ombeta;
m10 = alpha * ombeta;
m01 = omalpha * beta;
m11 = alpha * beta;
result->r = m00*t00.r + m10*t10.r + m01*t01.r + m11*t11.r;
result->g = m00*t00.g + m10*t10.g + m01*t01.g + m11*t11.g;
result->b = m00*t00.b + m10*t10.b + m01*t01.b + m11*t11.b;
}
void FASTCALL __glLinearFilter2_BGRA8Repeat(__GLcontext *gc, __GLtexture *tex,
__GLmipMapLevel *lp, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLtexel *result)
{
__GLfloat u, v, alpha, beta, half;
GLint col, row, rowLen;
__GLcolor t00, t01, t10, t11;
__GLfloat omalpha, ombeta, m00, m01, m10, m11;
GLint width2m1, height2m1;
GLubyte *image, *pData;
#ifdef __GL_LINT
color = color;
#endif
half = __glHalf;
width2m1 = lp->width2 - 1;
height2m1 = lp->height2 - 1;
/* Find col, compute alpha */
u = (s * lp->width2f) - half;
col = __GL_FAST_FLOORF_I(u);
alpha = u - (__GLfloat) col; // Get fractional part
col &= width2m1;
/* Find row, compute beta */
v = (t * lp->height2f) - half;
row = __GL_FAST_FLOORF_I(v);
beta = v - (__GLfloat) row; // Get fractional part
row &= height2m1;
// Extract first texel
pData = image =
(GLubyte *)lp->buffer + (((row << lp->widthLog2) + col) << 2);
// Extract the first texel at row, col
__glBGRAByteToFloat( &t00, pData );
// Extract remaining texels
rowLen = lp->width2 << 2; // row length in bytes
if( (row < height2m1) &&
(col < width2m1) )
{
// Most common case - the texels are a compact block of 4
// Next texel along row...
__glBGRAByteToFloat( &t10, pData );
// Up to next row...
pData += (rowLen-8);
__glBGRAByteToFloat( &t01, pData );
__glBGRAByteToFloat( &t11, pData );
} else {
// Exceptional case : one or both of row, col are on edge
GLint rowInc, colInc; // increments in bytes
// Calc increments to next texel along row/col
if( col < width2m1 )
rowInc = 4;
else
// increment to left edge
rowInc = -(rowLen - 4);
if( row < height2m1 )
// increment by row length
colInc = rowLen;
else
// increment to lower edge
colInc = - height2m1 * rowLen;
// Next texel along row
pData = image + rowInc;
__glBGRAByteToFloat( &t10, pData );
// Second row, first texel
pData = image + colInc;
__glBGRAByteToFloat( &t01, pData );
// Next texel along row
pData += (rowInc - 4);
__glBGRAByteToFloat( &t11, pData );
}
omalpha = __glOne - alpha;
ombeta = __glOne - beta;
m00 = omalpha * ombeta;
m10 = alpha * ombeta;
m01 = omalpha * beta;
m11 = alpha * beta;
result->r = m00*t00.r + m10*t10.r + m01*t01.r + m11*t11.r;
result->g = m00*t00.g + m10*t10.g + m01*t01.g + m11*t11.g;
result->b = m00*t00.b + m10*t10.b + m01*t01.b + m11*t11.b;
result->alpha = m00*t00.a + m10*t10.a + m01*t01.a + m11*t11.a;
}
/*
** Linear min/mag filter
*/
void FASTCALL __glLinearFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
#ifdef __GL_LINT
lod = lod;
#endif
(*tex->linear)(gc, tex, &tex->level[0], color, s, t, result);
}
/*
** Nearest min/mag filter
*/
void FASTCALL __glNearestFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
#ifdef __GL_LINT
lod = lod;
#endif
(*tex->nearest)(gc, tex, &tex->level[0], color, s, t, result);
}
/*
** Apply minification rules to find the texel value.
*/
void FASTCALL __glNMNFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
__GLmipMapLevel *lp;
GLint p, d;
if (lod <= ((__GLfloat)0.5)) {
d = 0;
} else {
p = tex->p;
d = FTOL(lod + ((__GLfloat)0.49995)); /* NOTE: .5 minus epsilon */
if (d > p) {
d = p;
}
}
lp = &tex->level[d];
(*tex->nearest)(gc, tex, lp, color, s, t, result);
}
/*
** Apply minification rules to find the texel value.
*/
void FASTCALL __glLMNFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
__GLmipMapLevel *lp;
GLint p, d;
if (lod <= ((__GLfloat) 0.5)) {
d = 0;
} else {
p = tex->p;
d = FTOL(lod + ((__GLfloat) 0.49995)); /* NOTE: .5 minus epsilon */
if (d > p) {
d = p;
}
}
lp = &tex->level[d];
(*tex->linear)(gc, tex, lp, color, s, t, result);
}
/*
** Apply minification rules to find the texel value.
*/
void FASTCALL __glNMLFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
__GLmipMapLevel *lp;
GLint p, d;
__GLtexel td, td1;
__GLfloat f, omf;
p = tex->p;
d = (FTOL(lod)) + 1;
if (d > p || d < 0) {
/* Clamp d to last available mipmap */
lp = &tex->level[p];
(*tex->nearest)(gc, tex, lp, color, s, t, result);
} else {
(*tex->nearest)(gc, tex, &tex->level[d], color, s, t, &td);
(*tex->nearest)(gc, tex, &tex->level[d-1], color, s, t, &td1);
f = __GL_FRAC(lod);
omf = __glOne - f;
switch (tex->level[0].baseFormat) {
case GL_LUMINANCE_ALPHA:
result->alpha = omf * td1.alpha + f * td.alpha;
/* FALLTHROUGH */
case GL_LUMINANCE:
result->luminance = omf * td1.luminance + f * td.luminance;
break;
case GL_RGBA:
result->alpha = omf * td1.alpha + f * td.alpha;
/* FALLTHROUGH */
case GL_RGB:
result->r = omf * td1.r + f * td.r;
result->g = omf * td1.g + f * td.g;
result->b = omf * td1.b + f * td.b;
break;
case GL_ALPHA:
result->alpha = omf * td1.alpha + f * td.alpha;
break;
case GL_INTENSITY:
result->intensity = omf * td1.intensity + f * td.intensity;
break;
}
}
}
/*
** Apply minification rules to find the texel value.
*/
void FASTCALL __glLMLFilter(__GLcontext *gc, __GLtexture *tex, __GLfloat lod,
__GLcolor *color, __GLfloat s, __GLfloat t,
__GLtexel *result)
{
__GLmipMapLevel *lp;
GLint p, d;
__GLtexel td, td1;
__GLfloat f, omf;
p = tex->p;
d = (FTOL(lod)) + 1;
if (d > p || d < 0) {
/* Clamp d to last available mipmap */
lp = &tex->level[p];
(*tex->linear)(gc, tex, lp, color, s, t, result);
} else {
(*tex->linear)(gc, tex, &tex->level[d], color, s, t, &td);
(*tex->linear)(gc, tex, &tex->level[d-1], color, s, t, &td1);
f = __GL_FRAC(lod);
omf = __glOne - f;
switch (tex->level[0].baseFormat) {
case GL_LUMINANCE_ALPHA:
result->alpha = omf * td1.alpha + f * td.alpha;
/* FALLTHROUGH */
case GL_LUMINANCE:
result->luminance = omf * td1.luminance + f * td.luminance;
break;
case GL_RGBA:
result->alpha = omf * td1.alpha + f * td.alpha;
/* FALLTHROUGH */
case GL_RGB:
result->r = omf * td1.r + f * td.r;
result->g = omf * td1.g + f * td.g;
result->b = omf * td1.b + f * td.b;
break;
case GL_ALPHA:
result->alpha = omf * td1.alpha + f * td.alpha;
break;
case GL_INTENSITY:
result->intensity = omf * td1.intensity + f * td.intensity;
break;
}
}
}
/************************************************************************/
__GLfloat __glNopPolygonRho(__GLcontext *gc, const __GLshade *sh,
__GLfloat s, __GLfloat t, __GLfloat winv)
{
#ifdef __GL_LINT
gc = gc;
sh = sh;
s = s;
t = t;
winv = winv;
#endif
return __glZero;
}
/*
** Compute the "rho" (level of detail) parameter used by the texturing code.
** Instead of fully computing the derivatives compute nearby texture coordinates
** and discover the derivative. The incoming s & t arguments have not
** been divided by winv yet.
*/
__GLfloat __glComputePolygonRho(__GLcontext *gc, const __GLshade *sh,
__GLfloat s, __GLfloat t, __GLfloat qw)
{
__GLfloat w0, w1, p0, p1;
__GLfloat pupx, pupy, pvpx, pvpy;
__GLfloat px, py, one;
__GLtexture *tex = gc->texture.currentTexture;
if( qw == (__GLfloat) 0.0 ) {
return (__GLfloat) 0.0;
}
/* Compute partial of u with respect to x */
one = __glOne;
w0 = one / (qw - sh->dqwdx);
w1 = one / (qw + sh->dqwdx);
p0 = (s - sh->dsdx) * w0;
p1 = (s + sh->dsdx) * w1;
pupx = (p1 - p0) * tex->level[0].width2f;
/* Compute partial of v with repsect to y */
p0 = (t - sh->dtdx) * w0;
p1 = (t + sh->dtdx) * w1;
pvpx = (p1 - p0) * tex->level[0].height2f;
/* Compute partial of u with respect to y */
w0 = one / (qw - sh->dqwdy);
w1 = one / (qw + sh->dqwdy);
p0 = (s - sh->dsdy) * w0;
p1 = (s + sh->dsdy) * w1;
pupy = (p1 - p0) * tex->level[0].width2f;
/* Figure partial of u&v with repsect to y */
p0 = (t - sh->dtdy) * w0;
p1 = (t + sh->dtdy) * w1;
pvpy = (p1 - p0) * tex->level[0].height2f;
/* Finally, figure sum of squares */
px = pupx * pupx + pvpx * pvpx;
py = pupy * pupy + pvpy * pvpy;
/* Return largest value as the level of detail */
if (px > py) {
return px * ((__GLfloat) 0.25);
} else {
return py * ((__GLfloat) 0.25);
}
}
__GLfloat __glNopLineRho(__GLcontext *gc, __GLfloat s, __GLfloat t,
__GLfloat wInv)
{
#ifdef __GL_LINT
gc = gc;
s = s;
t = t;
wInv = wInv;
#endif
return __glZero;
}
__GLfloat __glComputeLineRho(__GLcontext *gc, __GLfloat s, __GLfloat t,
__GLfloat wInv)
{
__GLfloat pspx, pspy, ptpx, ptpy;
__GLfloat pupx, pupy, pvpx, pvpy;
__GLfloat temp, pu, pv;
__GLfloat magnitude, invMag, invMag2;
__GLfloat dx, dy;
__GLfloat s0w0, s1w1, t0w0, t1w1, w1Inv, w0Inv;
const __GLvertex *v0 = gc->line.options.v0;
const __GLvertex *v1 = gc->line.options.v1;
/* Compute the length of the line (its magnitude) */
dx = v1->window.x - v0->window.x;
dy = v1->window.y - v0->window.y;
magnitude = __GL_SQRTF(dx*dx + dy*dy);
invMag = __glOne / magnitude;
invMag2 = invMag * invMag;
w0Inv = v0->window.w;
w1Inv = v1->window.w;
s0w0 = v0->texture.x * w0Inv;
t0w0 = v0->texture.y * w0Inv;
s1w1 = v1->texture.x * w1Inv;
t1w1 = v1->texture.y * w1Inv;
/* Compute s partials */
temp = ((s1w1 - s0w0) - s * (w1Inv - w0Inv)) / wInv;
pspx = temp * dx * invMag2;
pspy = temp * dy * invMag2;
/* Compute t partials */
temp = ((t1w1 - t0w0) - t * (w1Inv - w0Inv)) / wInv;
ptpx = temp * dx * invMag2;
ptpy = temp * dy * invMag2;
pupx = pspx * gc->texture.currentTexture->level[0].width2;
pupy = pspy * gc->texture.currentTexture->level[0].width2;
pvpx = ptpx * gc->texture.currentTexture->level[0].height2;
pvpy = ptpy * gc->texture.currentTexture->level[0].height2;
/* Now compute rho */
pu = pupx * dx + pupy * dy;
pu = pu * pu;
pv = pvpx * dx + pvpy * dy;
pv = pv * pv;
return (pu + pv) * invMag2;
}
/************************************************************************/
/*
** Fast texture a fragment assumes that rho is noise - this is true
** when no mipmapping is being done and the min and mag filters are
** the same.
*/
void __glFastTextureFragment(__GLcontext *gc, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLfloat rho)
{
__GLtexture *tex = gc->texture.currentTexture;
__GLtexel texel;
#ifdef __GL_LINT
rho = rho;
#endif
(*tex->magnify)(gc, tex, __glZero, color, s, t, &texel);
(*tex->env)(gc, color, &texel);
}
/*
** Non-mipmapping texturing function.
*/
void __glTextureFragment(__GLcontext *gc, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLfloat rho)
{
__GLtexture *tex = gc->texture.currentTexture;
__GLtexel texel;
if (rho <= tex->c) {
(*tex->magnify)(gc, tex, __glZero, color, s, t, &texel);
} else {
(*tex->minnify)(gc, tex, __glZero, color, s, t, &texel);
}
/* Now apply texture environment to get final color */
(*tex->env)(gc, color, &texel);
}
void __glMipMapFragment(__GLcontext *gc, __GLcolor *color,
__GLfloat s, __GLfloat t, __GLfloat rho)
{
__GLtexture *tex = gc->texture.currentTexture;
__GLtexel texel;
/* In the spec c is given in terms of lambda.
** Here c is compared to rho (really rho^2) and adjusted accordingly.
*/
if (rho <= tex->c) {
/* NOTE: rho is ignored by magnify proc */
(*tex->magnify)(gc, tex, rho, color, s, t, &texel);
} else {
if (rho) {
/* Convert rho to lambda */
/* This is an approximation of log base 2 */
// Note that these approximations are inaccurate for rho < 1.0, but
// rho is less than tex->c to get here. Since currently tex->c is
// a constant 1.0, this is not a problem.
// This method directly manipulates the floating point binary
// representation.
#define __GL_FLOAT_EXPONENT_ZERO \
(__GL_FLOAT_EXPONENT_BIAS << __GL_FLOAT_EXPONENT_SHIFT)
unsigned int lrho;
LONG exponent;
ASSERTOPENGL( rho >= 1.0f, "Log base 2 approximation not accurate");
// Extract exponent
lrho = CASTFIX(rho);
exponent = ( (lrho & __GL_FLOAT_EXPONENT_MASK)
>> __GL_FLOAT_EXPONENT_SHIFT )
- __GL_FLOAT_EXPONENT_BIAS;
// Extract fractional part of the floating point number
lrho &= ~__GL_FLOAT_EXPONENT_MASK; // dump current exponent
lrho |= __GL_FLOAT_EXPONENT_ZERO; // zap in zero exponent
// Convert back to float, subtract implicit mantissa 1.0, and
// add the exponent value to yield the approximation.
rho = (CASTFLOAT(lrho) - 1.0f + (__GLfloat) exponent) * 0.5f;
} else {
rho = __glZero;
}
(*tex->minnify)(gc, tex, rho, color, s, t, &texel);
}
/* Now apply texture environment to get final color */
(*tex->env)(gc, color, &texel);
}
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