/*
* Mesa 3-D graphics library
*
* Copyright (C) 1999-2007 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
* THE AUTHORS OR COPYRIGHT HOLDERS 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 "main/glheader.h"
#include "main/context.h"
#include "main/imports.h"
#include "main/format_pack.h"
#include "main/format_unpack.h"
#include "main/core.h"
#include "main/stencil.h"
#include "s_context.h"
#include "s_depth.h"
#include "s_stencil.h"
#include "s_span.h"
/* Stencil Logic:
IF stencil test fails THEN
Apply fail-op to stencil value
Don't write the pixel (RGBA,Z)
ELSE
IF doing depth test && depth test fails THEN
Apply zfail-op to stencil value
Write RGBA and Z to appropriate buffers
ELSE
Apply zpass-op to stencil value
ENDIF
*/
/**
* Compute/return the offset of the stencil value in a pixel.
* For example, if the format is Z24+S8, the position of the stencil bits
* within the 4-byte pixel will be either 0 or 3.
*/
static GLint
get_stencil_offset(gl_format format)
{
const GLubyte one = 1;
GLubyte pixel[MAX_PIXEL_BYTES];
GLint bpp = _mesa_get_format_bytes(format);
GLint i;
assert(_mesa_get_format_bits
(format
, GL_STENCIL_BITS
) == 8); memset(pixel
, 0, sizeof(pixel
)); _mesa_pack_ubyte_stencil_row(format, 1, &one, pixel);
for (i = 0; i < bpp; i++) {
if (pixel[i])
return i;
}
_mesa_problem(NULL, "get_stencil_offset() failed\n");
return 0;
}
/** Clamp the stencil value to [0, 255] */
static inline GLubyte
clamp(GLint val)
{
if (val < 0)
return 0;
else if (val > 255)
return 255;
else
return val;
}
#define STENCIL_OP(NEW_VAL) \
if (invmask == 0) { \
for (i = j = 0; i < n; i++, j += stride) { \
if (mask[i]) { \
GLubyte s = stencil[j]; \
(void) s; \
stencil[j] = (GLubyte) (NEW_VAL); \
} \
} \
} \
else { \
for (i = j = 0; i < n; i++, j += stride) { \
if (mask[i]) { \
GLubyte s = stencil[j]; \
stencil[j] = (GLubyte) ((invmask & s) | (wrtmask & (NEW_VAL))); \
} \
} \
}
/**
* Apply the given stencil operator to the array of stencil values.
* Don't touch stencil[i] if mask[i] is zero.
* @param n number of stencil values
* @param oper the stencil buffer operator
* @param face 0 or 1 for front or back face operation
* @param stencil array of stencil values (in/out)
* @param mask array [n] of flag: 1=apply operator, 0=don't apply operator
* @param stride stride between stencil values
*/
static void
apply_stencil_op(const struct gl_context *ctx, GLenum oper, GLuint face,
GLuint n, GLubyte stencil[], const GLubyte mask[],
GLint stride)
{
const GLubyte ref = _mesa_get_stencil_ref(ctx, face);
const GLubyte wrtmask = ctx->Stencil.WriteMask[face];
const GLubyte invmask = (GLubyte) (~wrtmask);
GLuint i, j;
switch (oper) {
case GL_KEEP:
/* do nothing */
break;
case GL_ZERO:
/* replace stencil buf values with zero */
STENCIL_OP(0);
break;
case GL_REPLACE:
/* replace stencil buf values with ref value */
STENCIL_OP(ref);
break;
case GL_INCR:
/* increment stencil buf values, with clamping */
STENCIL_OP(clamp(s + 1));
break;
case GL_DECR:
/* increment stencil buf values, with clamping */
STENCIL_OP(clamp(s - 1));
break;
case GL_INCR_WRAP_EXT:
/* increment stencil buf values, without clamping */
STENCIL_OP(s + 1);
break;
case GL_DECR_WRAP_EXT:
/* increment stencil buf values, without clamping */
STENCIL_OP(s - 1);
break;
case GL_INVERT:
/* replace stencil buf values with inverted value */
STENCIL_OP(~s);
break;
default:
_mesa_problem(ctx, "Bad stencil op in apply_stencil_op");
}
}
#define STENCIL_TEST(FUNC) \
for (i = j = 0; i < n; i++, j += stride) { \
if (mask[i]) { \
s = (GLubyte) (stencil[j] & valueMask); \
if (FUNC) { \
/* stencil pass */ \
fail[i] = 0; \
} \
else { \
/* stencil fail */ \
fail[i] = 1; \
mask[i] = 0; \
} \
} \
else { \
fail[i] = 0; \
} \
}
/**
* Apply stencil test to an array of stencil values (before depth buffering).
* For the values that fail, we'll apply the GL_STENCIL_FAIL operator to
* the stencil values.
*
* @param face 0 or 1 for front or back-face polygons
* @param n number of pixels in the array
* @param stencil array of [n] stencil values (in/out)
* @param mask array [n] of flag: 0=skip the pixel, 1=stencil the pixel,
* values are set to zero where the stencil test fails.
* @param stride stride between stencil values
* @return GL_FALSE = all pixels failed, GL_TRUE = zero or more pixels passed.
*/
static GLboolean
do_stencil_test(struct gl_context *ctx, GLuint face, GLuint n,
GLubyte stencil[], GLubyte mask[], GLint stride)
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
GLubyte *fail = swrast->stencil_temp.buf2;
GLboolean allfail = GL_FALSE;
GLuint i, j;
const GLuint valueMask = ctx->Stencil.ValueMask[face];
const GLubyte ref = (GLubyte) (_mesa_get_stencil_ref(ctx, face) & valueMask);
GLubyte s;
/*
* Perform stencil test. The results of this operation are stored
* in the fail[] array:
* IF fail[i] is non-zero THEN
* the stencil fail operator is to be applied
* ELSE
* the stencil fail operator is not to be applied
* ENDIF
*/
switch (ctx->Stencil.Function[face]) {
case GL_NEVER:
STENCIL_TEST(0);
allfail = GL_TRUE;
break;
case GL_LESS:
STENCIL_TEST(ref < s);
break;
case GL_LEQUAL:
STENCIL_TEST(ref <= s);
break;
case GL_GREATER:
STENCIL_TEST(ref > s);
break;
case GL_GEQUAL:
STENCIL_TEST(ref >= s);
break;
case GL_EQUAL:
STENCIL_TEST(ref == s);
break;
case GL_NOTEQUAL:
STENCIL_TEST(ref != s);
break;
case GL_ALWAYS:
STENCIL_TEST(1);
break;
default:
_mesa_problem(ctx, "Bad stencil func in gl_stencil_span");
return 0;
}
if (ctx->Stencil.FailFunc[face] != GL_KEEP) {
apply_stencil_op(ctx, ctx->Stencil.FailFunc[face], face, n, stencil,
fail, stride);
}
return !allfail;
}
/**
* Compute the zpass/zfail masks by comparing the pre- and post-depth test
* masks.
*/
static inline void
compute_pass_fail_masks(GLuint n, const GLubyte origMask[],
const GLubyte newMask[],
GLubyte passMask[], GLubyte failMask[])
{
GLuint i;
for (i = 0; i < n; i++) {
ASSERT(newMask[i] == 0 || newMask[i] == 1);
passMask[i] = origMask[i] & newMask[i];
failMask[i] = origMask[i] & (newMask[i] ^ 1);
}
}
/**
* Get 8-bit stencil values from random locations in the stencil buffer.
*/
static void
get_s8_values(struct gl_context *ctx, struct gl_renderbuffer *rb,
GLuint count, const GLint x[], const GLint y[],
GLubyte stencil[])
{
struct swrast_renderbuffer *srb = swrast_renderbuffer(rb);
const GLint w = rb->Width, h = rb->Height;
const GLubyte *map = _swrast_pixel_address(rb, 0, 0);
GLuint i;
if (rb->Format == MESA_FORMAT_S8) {
const GLint rowStride = srb->RowStride;
for (i = 0; i < count; i++) {
if (x[i] >= 0 && y[i] >= 0 && x[i] < w && y[i] < h) {
stencil[i] = *(map + y[i] * rowStride + x[i]);
}
}
}
else {
const GLint bpp = _mesa_get_format_bytes(rb->Format);
const GLint rowStride = srb->RowStride;
for (i = 0; i < count; i++) {
if (x[i] >= 0 && y[i] >= 0 && x[i] < w && y[i] < h) {
const GLubyte *src = map + y[i] * rowStride + x[i] * bpp;
_mesa_unpack_ubyte_stencil_row(rb->Format, 1, src, &stencil[i]);
}
}
}
}
/**
* Put 8-bit stencil values at random locations into the stencil buffer.
*/
static void
put_s8_values(struct gl_context *ctx, struct gl_renderbuffer *rb,
GLuint count, const GLint x[], const GLint y[],
const GLubyte stencil[])
{
const GLint w = rb->Width, h = rb->Height;
gl_pack_ubyte_stencil_func pack_stencil =
_mesa_get_pack_ubyte_stencil_func(rb->Format);
GLuint i;
for (i = 0; i < count; i++) {
if (x[i] >= 0 && y[i] >= 0 && x[i] < w && y[i] < h) {
GLubyte *dst = _swrast_pixel_address(rb, x[i], y[i]);
pack_stencil(&stencil[i], dst);
}
}
}
/**
* /return GL_TRUE = one or more fragments passed,
* GL_FALSE = all fragments failed.
*/
GLboolean
_swrast_stencil_and_ztest_span(struct gl_context *ctx, SWspan *span)
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
struct gl_framebuffer *fb = ctx->DrawBuffer;
struct gl_renderbuffer *rb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
const GLint stencilOffset = get_stencil_offset(rb->Format);
const GLint stencilStride = _mesa_get_format_bytes(rb->Format);
const GLuint face = (span->facing == 0) ? 0 : ctx->Stencil._BackFace;
const GLuint count = span->end;
GLubyte *mask = span->array->mask;
GLubyte *stencilTemp = swrast->stencil_temp.buf1;
GLubyte *stencilBuf;
if (span->arrayMask & SPAN_XY) {
/* read stencil values from random locations */
get_s8_values(ctx, rb, count, span->array->x, span->array->y,
stencilTemp);
stencilBuf = stencilTemp;
}
else {
/* Processing a horizontal run of pixels. Since stencil is always
* 8 bits for all MESA_FORMATs, we just need to use the right offset
* and stride to access them.
*/
stencilBuf = _swrast_pixel_address(rb, span->x, span->y) + stencilOffset;
}
/*
* Apply the stencil test to the fragments.
* failMask[i] is 1 if the stencil test failed.
*/
if (!do_stencil_test(ctx, face, count, stencilBuf, mask, stencilStride)) {
/* all fragments failed the stencil test, we're done. */
span->writeAll = GL_FALSE;
if (span->arrayMask & SPAN_XY) {
/* need to write the updated stencil values back to the buffer */
put_s8_values(ctx, rb, count, span->array->x, span->array->y,
stencilTemp);
}
return GL_FALSE;
}
/*
* Some fragments passed the stencil test, apply depth test to them
* and apply Zpass and Zfail stencil ops.
*/
if (ctx->Depth.Test == GL_FALSE ||
ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer == NULL) {
/*
* No depth buffer, just apply zpass stencil function to active pixels.
*/
apply_stencil_op(ctx, ctx->Stencil.ZPassFunc[face], face, count,
stencilBuf, mask, stencilStride);
}
else {
/*
* Perform depth buffering, then apply zpass or zfail stencil function.
*/
SWcontext *swrast = SWRAST_CONTEXT(ctx);
GLubyte *passMask = swrast->stencil_temp.buf2;
GLubyte *failMask = swrast->stencil_temp.buf3;
GLubyte *origMask = swrast->stencil_temp.buf4;
/* save the current mask bits */
memcpy(origMask
, mask
, count
* sizeof(GLubyte
));
/* apply the depth test */
_swrast_depth_test_span(ctx, span);
compute_pass_fail_masks(count, origMask, mask, passMask, failMask);
/* apply the pass and fail operations */
if (ctx->Stencil.ZFailFunc[face] != GL_KEEP) {
apply_stencil_op(ctx, ctx->Stencil.ZFailFunc[face], face,
count, stencilBuf, failMask, stencilStride);
}
if (ctx->Stencil.ZPassFunc[face] != GL_KEEP) {
apply_stencil_op(ctx, ctx->Stencil.ZPassFunc[face], face,
count, stencilBuf, passMask, stencilStride);
}
}
/* Write updated stencil values back into hardware stencil buffer */
if (span->arrayMask & SPAN_XY) {
put_s8_values(ctx, rb, count, span->array->x, span->array->y,
stencilBuf);
}
span->writeAll = GL_FALSE;
return GL_TRUE; /* one or more fragments passed both tests */
}
/**
* Return a span of stencil values from the stencil buffer.
* Used for glRead/CopyPixels
* Input: n - how many pixels
* x,y - location of first pixel
* Output: stencil - the array of stencil values
*/
void
_swrast_read_stencil_span(struct gl_context *ctx, struct gl_renderbuffer *rb,
GLint n, GLint x, GLint y, GLubyte stencil[])
{
GLubyte *src;
if (y < 0 || y >= (GLint) rb->Height ||
x + n <= 0 || x >= (GLint) rb->Width) {
/* span is completely outside framebuffer */
return; /* undefined values OK */
}
if (x < 0) {
GLint dx = -x;
x = 0;
n -= dx;
stencil += dx;
}
if (x + n > (GLint) rb->Width) {
GLint dx = x + n - rb->Width;
n -= dx;
}
if (n <= 0) {
return;
}
src = _swrast_pixel_address(rb, x, y);
_mesa_unpack_ubyte_stencil_row(rb->Format, n, src, stencil);
}
/**
* Write a span of stencil values to the stencil buffer. This function
* applies the stencil write mask when needed.
* Used for glDraw/CopyPixels
* Input: n - how many pixels
* x, y - location of first pixel
* stencil - the array of stencil values
*/
void
_swrast_write_stencil_span(struct gl_context *ctx, GLint n, GLint x, GLint y,
const GLubyte stencil[] )
{
SWcontext *swrast = SWRAST_CONTEXT(ctx);
struct gl_framebuffer *fb = ctx->DrawBuffer;
struct gl_renderbuffer *rb = fb->Attachment[BUFFER_STENCIL].Renderbuffer;
const GLuint stencilMax = (1 << fb->Visual.stencilBits) - 1;
const GLuint stencilMask = ctx->Stencil.WriteMask[0];
GLubyte *stencilBuf;
if (y < 0 || y >= (GLint) rb->Height ||
x + n <= 0 || x >= (GLint) rb->Width) {
/* span is completely outside framebuffer */
return; /* undefined values OK */
}
if (x < 0) {
GLint dx = -x;
x = 0;
n -= dx;
stencil += dx;
}
if (x + n > (GLint) rb->Width) {
GLint dx = x + n - rb->Width;
n -= dx;
}
if (n <= 0) {
return;
}
stencilBuf = _swrast_pixel_address(rb, x, y);
if ((stencilMask & stencilMax) != stencilMax) {
/* need to apply writemask */
GLubyte *destVals = swrast->stencil_temp.buf1;
GLubyte *newVals = swrast->stencil_temp.buf2;
GLint i;
_mesa_unpack_ubyte_stencil_row(rb->Format, n, stencilBuf, destVals);
for (i = 0; i < n; i++) {
newVals[i]
= (stencil[i] & stencilMask) | (destVals[i] & ~stencilMask);
}
_mesa_pack_ubyte_stencil_row(rb->Format, n, newVals, stencilBuf);
}
else {
_mesa_pack_ubyte_stencil_row(rb->Format, n, stencil, stencilBuf);
}
}
/**
* Clear the stencil buffer. If the buffer is a combined
* depth+stencil buffer, only the stencil bits will be touched.
*/
void
_swrast_clear_stencil_buffer(struct gl_context *ctx)
{
struct gl_renderbuffer *rb =
ctx->DrawBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
const GLubyte stencilBits = ctx->DrawBuffer->Visual.stencilBits;
const GLuint writeMask = ctx->Stencil.WriteMask[0];
const GLuint stencilMax = (1 << stencilBits) - 1;
GLint x, y, width, height;
GLubyte *map;
GLint rowStride, i, j;
GLbitfield mapMode;
if (!rb || writeMask == 0)
return;
/* compute region to clear */
x = ctx->DrawBuffer->_Xmin;
y = ctx->DrawBuffer->_Ymin;
width = ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
mapMode = GL_MAP_WRITE_BIT;
if ((writeMask & stencilMax) != stencilMax) {
/* need to mask stencil values */
mapMode |= GL_MAP_READ_BIT;
}
else if (_mesa_get_format_bits(rb->Format, GL_DEPTH_BITS) > 0) {
/* combined depth+stencil, need to mask Z values */
mapMode |= GL_MAP_READ_BIT;
}
ctx->Driver.MapRenderbuffer(ctx, rb, x, y, width, height,
mapMode, &map, &rowStride);
if (!map) {
_mesa_error(ctx, GL_OUT_OF_MEMORY, "glClear(stencil)");
return;
}
switch (rb->Format) {
case MESA_FORMAT_S8:
{
GLubyte clear = ctx->Stencil.Clear & writeMask & 0xff;
GLubyte mask = (~writeMask) & 0xff;
if (mask != 0) {
/* masked clear */
for (i = 0; i < height; i++) {
GLubyte *row = map;
for (j = 0; j < width; j++) {
row[j] = (row[j] & mask) | clear;
}
map += rowStride;
}
}
else if (rowStride == width) {
/* clear whole buffer */
memset(map
, clear
, width
* height
); }
else {
/* clear scissored */
for (i = 0; i < height; i++) {
map += rowStride;
}
}
}
break;
case MESA_FORMAT_S8_Z24:
{
GLuint clear = (ctx->Stencil.Clear & writeMask & 0xff) << 24;
GLuint mask = (((~writeMask) & 0xff) << 24) | 0xffffff;
for (i = 0; i < height; i++) {
GLuint *row = (GLuint *) map;
for (j = 0; j < width; j++) {
row[j] = (row[j] & mask) | clear;
}
map += rowStride;
}
}
break;
case MESA_FORMAT_Z24_S8:
{
GLuint clear = ctx->Stencil.Clear & writeMask & 0xff;
GLuint mask = 0xffffff00 | ((~writeMask) & 0xff);
for (i = 0; i < height; i++) {
GLuint *row = (GLuint *) map;
for (j = 0; j < width; j++) {
row[j] = (row[j] & mask) | clear;
}
map += rowStride;
}
}
break;
default:
_mesa_problem(ctx, "Unexpected stencil buffer format %s"
" in _swrast_clear_stencil_buffer()",
_mesa_get_format_name(rb->Format));
}
ctx->Driver.UnmapRenderbuffer(ctx, rb);
}