WebSVN - shark - Rev 57 - /shark/branches/xen/ports/mesa/src/swrast/s

/* $Id: s_accum.c,v 1.1 2003-02-28 11:49:40 pj Exp $ */

/*
* Mesa 3-D graphics library
* Version: 4.1
*
* Copyright (C) 1999-2002 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#include "glheader.h"
#include "context.h"
#include "macros.h"
#include "mmath.h"
#include "imports.h"

#include "s_accum.h"
#include "s_alphabuf.h"
#include "s_context.h"
#include "s_masking.h"
#include "s_span.h"

/*
* Accumulation buffer notes
*
* Normally, accumulation buffer values are GLshorts with values in
* [-32767, 32767] which represent floating point colors in [-1, 1],
* as suggested by the OpenGL specification.
*
* We optimize for the common case used for full-scene antialiasing:
* // start with accum buffer cleared to zero
* glAccum(GL_LOAD, w); // or GL_ACCUM the first image
* glAccum(GL_ACCUM, w);
* ...
* glAccum(GL_ACCUM, w);
* glAccum(GL_RETURN, 1.0);
* That is, we start with an empty accumulation buffer and accumulate
* n images, each with weight w = 1/n.
* In this scenario, we can simply store unscaled integer values in
* the accum buffer instead of scaled integers. We'll also keep track
* of the w value so when we do GL_RETURN we simply divide the accumulated
* values by n (=1/w).
* This lets us avoid _many_ int->float->int conversions.
*/

#if CHAN_BITS == 8 && ACCUM_BITS < 32
#define USE_OPTIMIZED_ACCUM /* enable the optimization */
#endif

void
_mesa_alloc_accum_buffer( GLframebuffer *buffer )
{
GET_CURRENT_CONTEXT(ctx);
GLint n;

if (buffer->Accum) {
MESA_PBUFFER_FREE( buffer->Accum );
buffer->Accum = NULL;
}

/* allocate accumulation buffer if not already present */
n = buffer->Width * buffer->Height * 4 * sizeof(GLaccum);
buffer->Accum = (GLaccum *) MESA_PBUFFER_ALLOC( n );
if (!buffer->Accum) {
/* unable to setup accumulation buffer */
_mesa_error( NULL, GL_OUT_OF_MEMORY, "glAccum" );
}

if (ctx) {
SWcontext *swrast = SWRAST_CONTEXT(ctx);
/* XXX these fields should probably be in the GLframebuffer */
#ifdef USE_OPTIMIZED_ACCUM
swrast->_IntegerAccumMode = GL_TRUE;
#else
swrast->_IntegerAccumMode = GL_FALSE;
#endif
swrast->_IntegerAccumScaler = 0.0;
}
}

/*
* This is called when we fall out of optimized/unscaled accum buffer mode.
* That is, we convert each unscaled accum buffer value into a scaled value
* representing the range[-1, 1].
*/
static void rescale_accum( GLcontext *ctx )
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
const GLuint n = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height * 4;
const GLfloat s = swrast->_IntegerAccumScaler * (32767.0F / CHAN_MAXF);
GLaccum *accum = ctx->DrawBuffer->Accum;
GLuint i;

assert(swrast->_IntegerAccumMode);
assert(accum);

for (i = 0; i < n; i++) {
accum[i] = (GLaccum) (accum[i] * s);
}

swrast->_IntegerAccumMode = GL_FALSE;
}

/*
* Clear the accumulation Buffer.
*/
void
_mesa_clear_accum_buffer( GLcontext *ctx )
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
GLuint buffersize;
GLfloat acc_scale;

if (ctx->Visual.accumRedBits==0) {
/* No accumulation buffer! */
return;
}

if (sizeof(GLaccum)==1) {
acc_scale = 127.0;
}
else if (sizeof(GLaccum)==2) {
acc_scale = 32767.0;
}
else {
acc_scale = 1.0F;
}

/* number of pixels */
buffersize = ctx->DrawBuffer->Width * ctx->DrawBuffer->Height;

if (!ctx->DrawBuffer->Accum) {
/* try to alloc accumulation buffer */
ctx->DrawBuffer->Accum = (GLaccum *)
MALLOC( buffersize * 4 * sizeof(GLaccum) );
}

if (ctx->DrawBuffer->Accum) {
if (ctx->Scissor.Enabled) {
/* Limit clear to scissor box */
const GLaccum r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
const GLaccum g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
const GLaccum b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
const GLaccum a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
GLint i, j;
GLint width, height;
GLaccum *row;
/* size of region to clear */
width = 4 * (ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin);
height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
/* ptr to first element to clear */
row = ctx->DrawBuffer->Accum
+ 4 * (ctx->DrawBuffer->_Ymin * ctx->DrawBuffer->Width
+ ctx->DrawBuffer->_Xmin);
for (j=0;j<height;j++) {
for (i=0;i<width;i+=4) {
row[i+0] = r;
row[i+1] = g;
row[i+2] = b;
row[i+3] = a;
}
row += 4 * ctx->DrawBuffer->Width;
}
}
else {
/* clear whole buffer */
if (ctx->Accum.ClearColor[0]==0.0 &&
ctx->Accum.ClearColor[1]==0.0 &&
ctx->Accum.ClearColor[2]==0.0 &&
ctx->Accum.ClearColor[3]==0.0) {
/* Black */
_mesa_bzero( ctx->DrawBuffer->Accum,
buffersize * 4 * sizeof(GLaccum) );
}
else {
/* Not black */
const GLaccum r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
const GLaccum g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
const GLaccum b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
const GLaccum a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
GLaccum *acc = ctx->DrawBuffer->Accum;
GLuint i;
for (i=0;i<buffersize;i++) {
*acc++ = r;
*acc++ = g;
*acc++ = b;
*acc++ = a;
}
}
}

/* update optimized accum state vars */
if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
#ifdef USE_OPTIMIZED_ACCUM
swrast->_IntegerAccumMode = GL_TRUE;
#else
swrast->_IntegerAccumMode = GL_FALSE;
#endif
swrast->_IntegerAccumScaler = 0.0; /* denotes empty accum buffer */
}
else {
swrast->_IntegerAccumMode = GL_FALSE;
}
}
}

void
_swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
GLint xpos, GLint ypos,
GLint width, GLint height )

{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
GLuint width4;
GLfloat acc_scale;
GLchan rgba[MAX_WIDTH][4];
const GLuint colorMask = *((GLuint *) &ctx->Color.ColorMask);

if (SWRAST_CONTEXT(ctx)->NewState)
_swrast_validate_derived( ctx );

if (!ctx->DrawBuffer->Accum) {
_mesa_warning(ctx,
"Calling glAccum() without an accumulation "
"buffer (low memory?)");
return;
}

if (sizeof(GLaccum)==1) {
acc_scale = 127.0;
}
else if (sizeof(GLaccum)==2) {
acc_scale = 32767.0;
}
else {
acc_scale = 1.0F;
}

width4 = 4 * width;

switch (op) {
case GL_ADD:
if (value != 0.0F) {
const GLaccum val = (GLaccum) (value * acc_scale);
GLint j;
/* Leave optimized accum buffer mode */
if (swrast->_IntegerAccumMode)
rescale_accum(ctx);
for (j = 0; j < height; j++) {
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4*xpos;
GLuint i;
for (i = 0; i < width4; i++) {
acc[i] += val;
}
ypos++;
}
}
break;

case GL_MULT:
if (value != 1.0F) {
GLint j;
/* Leave optimized accum buffer mode */
if (swrast->_IntegerAccumMode)
rescale_accum(ctx);
for (j = 0; j < height; j++) {
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + 4 * xpos;
GLuint i;
for (i = 0; i < width4; i++) {
acc[i] = (GLaccum) ( (GLfloat) acc[i] * value );
}
ypos++;
}
}
break;

case GL_ACCUM:
if (value == 0.0F)
return;

_swrast_use_read_buffer(ctx);

/* May have to leave optimized accum buffer mode */
if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
swrast->_IntegerAccumScaler = value;
if (swrast->_IntegerAccumMode && value != swrast->_IntegerAccumScaler)
rescale_accum(ctx);

RENDER_START(swrast,ctx);

if (swrast->_IntegerAccumMode) {
/* simply add integer color values into accum buffer */
GLint j;
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
assert(swrast->_IntegerAccumScaler > 0.0);
assert(swrast->_IntegerAccumScaler <= 1.0);
for (j = 0; j < height; j++) {

GLint i, i4;
_mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
for (i = i4 = 0; i < width; i++, i4+=4) {
acc[i4+0] += rgba[i][RCOMP];
acc[i4+1] += rgba[i][GCOMP];
acc[i4+2] += rgba[i][BCOMP];
acc[i4+3] += rgba[i][ACOMP];
}
acc += width4;
ypos++;
}
}
else {
/* scaled integer (or float) accum buffer */
const GLfloat rscale = value * acc_scale / CHAN_MAXF;
const GLfloat gscale = value * acc_scale / CHAN_MAXF;
const GLfloat bscale = value * acc_scale / CHAN_MAXF;
const GLfloat ascale = value * acc_scale / CHAN_MAXF;
GLint j;
for (j=0;j<height;j++) {
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
GLint i;
_mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
for (i=0;i<width;i++) {
acc[0] += (GLaccum) ( (GLfloat) rgba[i][RCOMP] * rscale );
acc[1] += (GLaccum) ( (GLfloat) rgba[i][GCOMP] * gscale );
acc[2] += (GLaccum) ( (GLfloat) rgba[i][BCOMP] * bscale );
acc[3] += (GLaccum) ( (GLfloat) rgba[i][ACOMP] * ascale );
acc += 4;
}
ypos++;
}
}
/* restore read buffer = draw buffer (the default) */
_swrast_use_draw_buffer(ctx);

RENDER_FINISH(swrast,ctx);
break;

case GL_LOAD:
_swrast_use_read_buffer(ctx);

/* This is a change to go into optimized accum buffer mode */
if (value > 0.0 && value <= 1.0) {
#ifdef USE_OPTIMIZED_ACCUM
swrast->_IntegerAccumMode = GL_TRUE;
#else
swrast->_IntegerAccumMode = GL_FALSE;
#endif
swrast->_IntegerAccumScaler = value;
}
else {
swrast->_IntegerAccumMode = GL_FALSE;
swrast->_IntegerAccumScaler = 0.0;
}

RENDER_START(swrast,ctx);
if (swrast->_IntegerAccumMode) {
/* just copy values into accum buffer */
GLint j;
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
assert(swrast->_IntegerAccumScaler > 0.0);
assert(swrast->_IntegerAccumScaler <= 1.0);
for (j = 0; j < height; j++) {
GLint i, i4;
_mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
for (i = i4 = 0; i < width; i++, i4 += 4) {
acc[i4+0] = rgba[i][RCOMP];
acc[i4+1] = rgba[i][GCOMP];
acc[i4+2] = rgba[i][BCOMP];
acc[i4+3] = rgba[i][ACOMP];
}
acc += width4;
ypos++;
}
}
else {
/* scaled integer (or float) accum buffer */
const GLfloat rscale = value * acc_scale / CHAN_MAXF;
const GLfloat gscale = value * acc_scale / CHAN_MAXF;
const GLfloat bscale = value * acc_scale / CHAN_MAXF;
const GLfloat ascale = value * acc_scale / CHAN_MAXF;
#if 0
const GLfloat d = 3.0 / acc_scale; /* XXX what's this? */
#endif
GLint i, j;
for (j = 0; j < height; j++) {
GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos * 4;
_mesa_read_rgba_span(ctx, ctx->DrawBuffer, width, xpos, ypos, rgba);
for (i=0;i<width;i++) {
#if 0
*acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale + d);
*acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale + d);
*acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale + d);
*acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale + d);
#else
*acc++ = (GLaccum) ((GLfloat) rgba[i][RCOMP] * rscale);
*acc++ = (GLaccum) ((GLfloat) rgba[i][GCOMP] * gscale);
*acc++ = (GLaccum) ((GLfloat) rgba[i][BCOMP] * bscale);
*acc++ = (GLaccum) ((GLfloat) rgba[i][ACOMP] * ascale);
#endif
}
ypos++;
}
}

/* restore read buffer = draw buffer (the default) */
_swrast_use_draw_buffer(ctx);

RENDER_FINISH(swrast,ctx);
break;

case GL_RETURN:
/* May have to leave optimized accum buffer mode */
if (swrast->_IntegerAccumMode && value != 1.0)
rescale_accum(ctx);

RENDER_START(swrast,ctx);
#ifdef USE_OPTIMIZED_ACCUM
if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {
/* build lookup table to avoid many floating point multiplies */
static GLchan multTable[32768];
static GLfloat prevMult = 0.0;
const GLfloat mult = swrast->_IntegerAccumScaler;
const GLint max = MIN2((GLint) (256 / mult), 32767);
GLint j;
if (mult != prevMult) {
for (j = 0; j < max; j++)
multTable[j] = IROUND((GLfloat) j * mult);
prevMult = mult;
}

assert(swrast->_IntegerAccumScaler > 0.0);
assert(swrast->_IntegerAccumScaler <= 1.0);
for (j = 0; j < height; j++) {
const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
GLint i, i4;
for (i = i4 = 0; i < width; i++, i4 += 4) {
ASSERT(acc[i4+0] < max);
ASSERT(acc[i4+1] < max);
ASSERT(acc[i4+2] < max);
ASSERT(acc[i4+3] < max);
rgba[i][RCOMP] = multTable[acc[i4+0]];
rgba[i][GCOMP] = multTable[acc[i4+1]];
rgba[i][BCOMP] = multTable[acc[i4+2]];
rgba[i][ACOMP] = multTable[acc[i4+3]];
}
if (colorMask != 0xffffffff) {
_mesa_mask_rgba_array( ctx, width, xpos, ypos, rgba );
}
(*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
(const GLchan (*)[4])rgba, NULL );
if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
&& ctx->Color.ColorMask[ACOMP]) {
_mesa_write_alpha_span(ctx, width, xpos, ypos,
(CONST GLchan (*)[4]) rgba, NULL);
}
ypos++;
}
}
else
#endif /* USE_OPTIMIZED_ACCUM */
{
/* scaled integer (or float) accum buffer */
const GLfloat rscale = value / acc_scale * CHAN_MAXF;
const GLfloat gscale = value / acc_scale * CHAN_MAXF;
const GLfloat bscale = value / acc_scale * CHAN_MAXF;
const GLfloat ascale = value / acc_scale * CHAN_MAXF;
GLint i, j;
for (j=0;j<height;j++) {
const GLaccum *acc = ctx->DrawBuffer->Accum + ypos * width4 + xpos*4;
for (i=0;i<width;i++) {
GLint r = IROUND( (GLfloat) (acc[0]) * rscale );
GLint g = IROUND( (GLfloat) (acc[1]) * gscale );
GLint b = IROUND( (GLfloat) (acc[2]) * bscale );
GLint a = IROUND( (GLfloat) (acc[3]) * ascale );
acc += 4;
rgba[i][RCOMP] = CLAMP( r, 0, CHAN_MAX );
rgba[i][GCOMP] = CLAMP( g, 0, CHAN_MAX );
rgba[i][BCOMP] = CLAMP( b, 0, CHAN_MAX );
rgba[i][ACOMP] = CLAMP( a, 0, CHAN_MAX );
}
if (colorMask != 0xffffffff) {
_mesa_mask_rgba_array( ctx, width, xpos, ypos, rgba );
}
(*swrast->Driver.WriteRGBASpan)( ctx, width, xpos, ypos,
(const GLchan (*)[4])rgba, NULL );
if (ctx->DrawBuffer->UseSoftwareAlphaBuffers
&& ctx->Color.ColorMask[ACOMP]) {
_mesa_write_alpha_span(ctx, width, xpos, ypos,
(CONST GLchan (*)[4]) rgba, NULL);
}
ypos++;
}
}
RENDER_FINISH(swrast,ctx);
break;

default:
_mesa_error( ctx, GL_INVALID_ENUM, "glAccum" );
}
}

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