You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
304 lines
10 KiB
304 lines
10 KiB
/*
|
|
** Copyright 1991, 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** This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics, Inc.;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 Unpublished -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.
|
|
**
|
|
** $Revision: 1.10 $
|
|
** $Date: 1993/06/18 00:30:15 $
|
|
*/
|
|
#include "precomp.h"
|
|
#pragma hdrstop
|
|
|
|
#include <fixed.h>
|
|
|
|
/*
|
|
** This is a little wierd. What it does is to dither "comp" into the high
|
|
** n-4 bits, and add 16 * antiAliasPercent. Dithering of the low bits is
|
|
** left to the usual methods (the store and span procs, for example).
|
|
*/
|
|
__GLfloat __glBuildAntiAliasIndex(__GLfloat index,
|
|
__GLfloat antiAliasPercent)
|
|
{
|
|
GLint newlowbits;
|
|
|
|
newlowbits = (GLint)((__GL_CI_ANTI_ALIAS_DIVISOR - 1) * antiAliasPercent + (__GLfloat) 0.5);
|
|
return (((int) index) & ~(__GL_CI_ANTI_ALIAS_DIVISOR - 1)) | newlowbits;
|
|
}
|
|
|
|
/************************************************************************/
|
|
|
|
/*
|
|
** To anti-alias points the below code operates a simple algrorithim that
|
|
** sub-samples the bounding box of the pixel area covered by the point.
|
|
** At each sub-sample the distance from the sample to the center of the
|
|
** point is computed and compared against the distance from the edge of
|
|
** the circle to the center. If the computed distance is <= the edge
|
|
** distance then the sample is inside the circle. All the samples for a
|
|
** particular pixel center are summed up and then the resulting value is
|
|
** divided by the total samples in the pixel. This gives us a coverage value
|
|
** to use to adjust the fragment alpha with before storing (there is
|
|
** an analagous affect when color index anti-aliasing is being done).
|
|
**
|
|
** The code below implements this simple algrorithim, but has been tuned
|
|
** so it might be difficult to translate. Basically, every possible operation
|
|
** that could be moved out of the Coverage code (i.e., invariants across
|
|
** the coverage test) has been done. Also, the minimal area is sampled
|
|
** over.
|
|
*/
|
|
|
|
/* Code below knows alot about these constants so beware */
|
|
#define __GL_FILTER_SIZE __glOne
|
|
#define __GL_HALF_FILTER_SIZE __glHalf
|
|
#define __GL_SAMPLES 4
|
|
#define __GL_SAMPLE_HIT ((__GLfloat) 0.0625) /* 1 / (4*4) */
|
|
#define __GL_SAMPLE_DELTA ((__GLfloat) 0.25) /* 1 / 4 */
|
|
#define __GL_HALF_SAMPLE_DELTA ((__GLfloat) 0.125)
|
|
/* -halffilter + half delta */
|
|
#define __GL_COORD_ADJUST ((__GLfloat) -0.375)
|
|
|
|
/*
|
|
** Return an estimate of the pixel coverage using sub-sampling.
|
|
**
|
|
** NOTE: The subtraction of xCenter,yCenter has been moved into the
|
|
** caller to save time. Consequently the starting coordinate may not be
|
|
** on a pixel center, but thats ok.
|
|
*/
|
|
static __GLfloat Coverage(__GLfloat xStart, __GLfloat yStart,
|
|
__GLfloat radiusSquared)
|
|
{
|
|
GLint i;
|
|
__GLfloat delta, yBottom, sampleX, sampleY;
|
|
__GLfloat hits, hitsInc;
|
|
|
|
/*
|
|
** Get starting sample x & y positions. We take our starting
|
|
** coordinate, back off half a filter size then add half a delta to
|
|
** it. This constrains the sampling to lie entirely within the
|
|
** pixel, never on the edges of the pixel. The constants above
|
|
** have this adjustment pre-computed.
|
|
*/
|
|
sampleX = xStart + __GL_COORD_ADJUST;
|
|
yBottom = yStart + __GL_COORD_ADJUST;
|
|
|
|
delta = __GL_SAMPLE_DELTA;
|
|
hits = __glZero;
|
|
hitsInc = __GL_SAMPLE_HIT;
|
|
for (i = __GL_SAMPLES; --i >= 0; ) {
|
|
__GLfloat check = radiusSquared - sampleX * sampleX;
|
|
|
|
/* Unrolled inner loop - change this code if __GL_SAMPLES changes */
|
|
sampleY = yBottom;
|
|
if (sampleY * sampleY <= check) {
|
|
hits += hitsInc;
|
|
}
|
|
sampleY += delta;
|
|
if (sampleY * sampleY <= check) {
|
|
hits += hitsInc;
|
|
}
|
|
sampleY += delta;
|
|
if (sampleY * sampleY <= check) {
|
|
hits += hitsInc;
|
|
}
|
|
sampleY += delta;
|
|
if (sampleY * sampleY <= check) {
|
|
hits += hitsInc;
|
|
}
|
|
|
|
sampleX += delta;
|
|
}
|
|
return hits;
|
|
}
|
|
|
|
void FASTCALL __glRenderAntiAliasedRGBPoint(__GLcontext *gc, __GLvertex *vx)
|
|
{
|
|
__GLfloat xCenter, yCenter, radius, radiusSquared, coverage, x, y;
|
|
__GLfloat zero, one, oldAlpha, xStart;
|
|
__GLfloat tmp;
|
|
__GLfragment frag;
|
|
GLint w, width, height, ixLeft, iyBottom;
|
|
GLuint modeFlags = gc->polygon.shader.modeFlags;
|
|
|
|
/*
|
|
** Determine area to compute coverage over. The area is bloated by
|
|
** the filter's width & height implicitly. By truncating to integer
|
|
** (NOTE: the x,y coordinate is always positive here) we are
|
|
** guaranteed to find the lowest coordinate that needs examination
|
|
** because of the nature of circles. Similarly, by truncating the
|
|
** ending coordinate and adding one we get the pixel just past the
|
|
** upper/right edge of the circle.
|
|
*/
|
|
radius = gc->state.point.smoothSize * __glHalf;
|
|
radiusSquared = radius * radius;
|
|
xCenter = vx->window.x;
|
|
yCenter = vx->window.y;
|
|
|
|
/* Truncate down to get starting coordinate */
|
|
tmp = xCenter-radius;
|
|
ixLeft = __GL_VERTEX_FLOAT_TO_INT(tmp);
|
|
tmp = yCenter-radius;
|
|
iyBottom = __GL_VERTEX_FLOAT_TO_INT(tmp);
|
|
|
|
/*
|
|
** Truncate down and add 1 to get the ending coordinate, then subtract
|
|
** out the start to get the width & height.
|
|
*/
|
|
tmp = xCenter+radius;
|
|
width = __GL_VERTEX_FLOAT_TO_INT(tmp) + 1 - ixLeft;
|
|
tmp = yCenter+radius;
|
|
height = __GL_VERTEX_FLOAT_TO_INT(tmp) + 1 - iyBottom;
|
|
|
|
/*
|
|
** Setup fragment. The fragment base color will be constant
|
|
** (approximately) across the entire pixel. The only thing that will
|
|
** change is the alpha (for rgb) or the red component (for color
|
|
** index).
|
|
*/
|
|
frag.z = (__GLzValue)vx->window.z;
|
|
frag.color = *vx->color;
|
|
if (modeFlags & __GL_SHADE_TEXTURE) {
|
|
(*gc->procs.texture)(gc, &frag.color, vx->texture.x, vx->texture.y,
|
|
__glOne);
|
|
}
|
|
|
|
if (gc->polygon.shader.modeFlags & __GL_SHADE_COMPUTE_FOG)
|
|
{
|
|
(*gc->procs.fogPoint)(gc, &frag, vx->eyeZ);
|
|
}
|
|
else if ((gc->polygon.shader.modeFlags & __GL_SHADE_INTERP_FOG)
|
|
||
|
|
((modeFlags & (__GL_SHADE_CHEAP_FOG | __GL_SHADE_SMOOTH_LIGHT))
|
|
== __GL_SHADE_CHEAP_FOG))
|
|
{
|
|
(*gc->procs.fogColor)(gc, &frag.color, &frag.color, vx->fog);
|
|
}
|
|
|
|
|
|
/*
|
|
** Now render the circle centered on xCenter,yCenter. Move the
|
|
** subtraction of xCenter,yCenter outside of the loop to doing
|
|
** it up front in xStart and y. This way the coverage code can
|
|
** assume the incoming starting coordinate has been properly
|
|
** adjusted.
|
|
*/
|
|
zero = __glZero;
|
|
one = __glOne;
|
|
oldAlpha = frag.color.a;
|
|
xStart = ixLeft + __glHalf - xCenter;
|
|
y = iyBottom + __glHalf - yCenter;
|
|
frag.y = iyBottom;
|
|
while (--height >= 0) {
|
|
x = xStart;
|
|
frag.x = ixLeft;
|
|
for (w = width; --w >= 0; ) {
|
|
coverage = Coverage(x, y, radiusSquared);
|
|
if (coverage > zero) {
|
|
frag.color.a = oldAlpha * coverage;
|
|
(*gc->procs.store)(gc->drawBuffer, &frag);
|
|
}
|
|
x += one;
|
|
frag.x++;
|
|
}
|
|
y += one;
|
|
frag.y++;
|
|
}
|
|
}
|
|
|
|
void FASTCALL __glRenderAntiAliasedCIPoint(__GLcontext *gc, __GLvertex *vx)
|
|
{
|
|
__GLfloat xCenter, yCenter, radius, radiusSquared, coverage, x, y;
|
|
__GLfloat zero, one, oldIndex, xStart;
|
|
__GLfloat tmp;
|
|
__GLfragment frag;
|
|
GLint w, width, height, ixLeft, iyBottom;
|
|
|
|
/*
|
|
** Determine area to compute coverage over. The area is bloated by
|
|
** the filter's width & height implicitly. By truncating to integer
|
|
** (NOTE: the x,y coordinate is always positive here) we are
|
|
** guaranteed to find the lowest coordinate that needs examination
|
|
** because of the nature of circles. Similarly, by truncating the
|
|
** ending coordinate and adding one we get the pixel just past the
|
|
** upper/right edge of the circle.
|
|
*/
|
|
radius = gc->state.point.smoothSize * __glHalf;
|
|
radiusSquared = radius * radius;
|
|
xCenter = vx->window.x;
|
|
yCenter = vx->window.y;
|
|
|
|
/* Truncate down to get starting coordinate */
|
|
tmp = xCenter-radius;
|
|
ixLeft = __GL_VERTEX_FLOAT_TO_INT(tmp);
|
|
tmp = yCenter-radius;
|
|
iyBottom = __GL_VERTEX_FLOAT_TO_INT(tmp);
|
|
|
|
/*
|
|
** Truncate down and add 1 to get the ending coordinate, then subtract
|
|
** out the start to get the width & height.
|
|
*/
|
|
tmp = xCenter+radius;
|
|
width = __GL_VERTEX_FLOAT_TO_INT(tmp) + 1 - ixLeft;
|
|
tmp = yCenter+radius;
|
|
height = __GL_VERTEX_FLOAT_TO_INT(tmp) + 1 - iyBottom;
|
|
|
|
/*
|
|
** Setup fragment. The fragment base color will be constant
|
|
** (approximately) across the entire pixel. The only thing that will
|
|
** change is the alpha (for rgb) or the red component (for color
|
|
** index).
|
|
*/
|
|
frag.z = (__GLzValue)vx->window.z;
|
|
frag.color.r = vx->color->r;
|
|
|
|
if (gc->polygon.shader.modeFlags & __GL_SHADE_COMPUTE_FOG)
|
|
{
|
|
(*gc->procs.fogPoint)(gc, &frag, vx->eyeZ);
|
|
}
|
|
else if ((gc->polygon.shader.modeFlags & __GL_SHADE_INTERP_FOG)
|
|
||
|
|
((gc->polygon.shader.modeFlags & (__GL_SHADE_CHEAP_FOG |
|
|
__GL_SHADE_SMOOTH_LIGHT))
|
|
== __GL_SHADE_CHEAP_FOG))
|
|
{
|
|
(*gc->procs.fogColor)(gc, &frag.color, &frag.color, vx->fog);
|
|
}
|
|
|
|
/*
|
|
** Now render the circle centered on xCenter,yCenter. Move the
|
|
** subtraction of xCenter,yCenter outside of the loop to doing
|
|
** it up front in xStart and y. This way the coverage code can
|
|
** assume the incoming starting coordinate has been properly
|
|
** adjusted.
|
|
*/
|
|
zero = __glZero;
|
|
one = __glOne;
|
|
oldIndex = frag.color.r;
|
|
xStart = ixLeft + __glHalf - xCenter;
|
|
y = iyBottom + __glHalf - yCenter;
|
|
frag.y = iyBottom;
|
|
while (--height >= 0) {
|
|
x = xStart;
|
|
frag.x = ixLeft;
|
|
for (w = width; --w >= 0; ) {
|
|
coverage = Coverage(x, y, radiusSquared);
|
|
if (coverage > zero) {
|
|
frag.color.r = __glBuildAntiAliasIndex(oldIndex, coverage);
|
|
(*gc->procs.store)(gc->drawBuffer, &frag);
|
|
}
|
|
x += one;
|
|
frag.x++;
|
|
}
|
|
y += one;
|
|
frag.y++;
|
|
}
|
|
}
|