/*
* Mesa 3-D graphics library
* Version: 7.0
*
* 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
* 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.
*/
/*
* Triangle Rasterizer Template
*
* This file is #include'd to generate custom triangle rasterizers.
*
* The following macros may be defined to indicate what auxillary information
* must be interpolated across the triangle:
* INTERP_Z - if defined, interpolate integer Z values
* INTERP_RGB - if defined, interpolate integer RGB values
* INTERP_ALPHA - if defined, interpolate integer Alpha values
* INTERP_INT_TEX - if defined, interpolate integer ST texcoords
* (fast, simple 2-D texture mapping, without
* perspective correction)
* INTERP_ATTRIBS - if defined, interpolate arbitrary attribs (texcoords,
* varying vars, etc) This also causes W to be
* computed for perspective correction).
*
* When one can directly address pixels in the color buffer the following
* macros can be defined and used to compute pixel addresses during
* rasterization (see pRow):
* PIXEL_TYPE - the datatype of a pixel (GLubyte, GLushort, GLuint)
* BYTES_PER_ROW - number of bytes per row in the color buffer
* PIXEL_ADDRESS(X,Y) - returns the address of pixel at (X,Y) where
* Y==0 at bottom of screen and increases upward.
*
* Similarly, for direct depth buffer access, this type is used for depth
* buffer addressing (see zRow):
* DEPTH_TYPE - either GLushort or GLuint
*
* Optionally, one may provide one-time setup code per triangle:
* SETUP_CODE - code which is to be executed once per triangle
*
* The following macro MUST be defined:
* RENDER_SPAN(span) - code to write a span of pixels.
*
* This code was designed for the origin to be in the lower-left corner.
*
* Inspired by triangle rasterizer code written by Allen Akin. Thanks Allen!
*
*
* Some notes on rasterization accuracy:
*
* This code uses fixed point arithmetic (the GLfixed type) to iterate
* over the triangle edges and interpolate ancillary data (such as Z,
* color, secondary color, etc). The number of fractional bits in
* GLfixed and the value of SUB_PIXEL_BITS has a direct bearing on the
* accuracy of rasterization.
*
* If SUB_PIXEL_BITS=4 then we'll snap the vertices to the nearest
* 1/16 of a pixel. If we're walking up a long, nearly vertical edge
* (dx=1/16, dy=1024) we'll need 4 + 10 = 14 fractional bits in
* GLfixed to walk the edge without error. If the maximum viewport
* height is 4K pixels, then we'll need 4 + 12 = 16 fractional bits.
*
* Historically, Mesa has used 11 fractional bits in GLfixed, snaps
* vertices to 1/16 pixel and allowed a maximum viewport height of 2K
* pixels. 11 fractional bits is actually insufficient for accurately
* rasterizing some triangles. More recently, the maximum viewport
* height was increased to 4K pixels. Thus, Mesa should be using 16
* fractional bits in GLfixed. Unfortunately, there may be some issues
* with setting FIXED_FRAC_BITS=16, such as multiplication overflow.
* This will have to be examined in some detail...
*
* For now, if you find rasterization errors, particularly with tall,
* sliver triangles, try increasing FIXED_FRAC_BITS and/or decreasing
* SUB_PIXEL_BITS.
*/
/*
* Some code we unfortunately need to prevent negative interpolated colors.
*/
#ifndef CLAMP_INTERPOLANT
#define CLAMP_INTERPOLANT(CHANNEL, CHANNELSTEP, LEN) \
do { \
GLfixed endVal = span.CHANNEL + (LEN) * span.CHANNELSTEP; \
if (endVal < 0) { \
span.CHANNEL -= endVal; \
} \
if (span.CHANNEL < 0) { \
span.CHANNEL = 0; \
} \
} while (0)
#endif
static void NAME(struct gl_context *ctx, const SWvertex *v0,
const SWvertex *v1,
const SWvertex *v2 )
{
typedef struct {
const SWvertex *v0, *v1; /* Y(v0) < Y(v1) */
GLfloat dx; /* X(v1) - X(v0) */
GLfloat dy; /* Y(v1) - Y(v0) */
GLfloat dxdy; /* dx/dy */
GLfixed fdxdy; /* dx/dy in fixed-point */
GLfloat adjy; /* adjust from v[0]->fy to fsy, scaled */
GLfixed fsx; /* first sample point x coord */
GLfixed fsy;
GLfixed fx0; /* fixed pt X of lower endpoint */
GLint lines; /* number of lines to be sampled on this edge */
} EdgeT;
const SWcontext *swrast = SWRAST_CONTEXT(ctx);
#ifdef INTERP_Z
const GLint depthBits = ctx->DrawBuffer->Visual.depthBits;
const GLint fixedToDepthShift = depthBits <= 16 ? FIXED_SHIFT : 0;
const GLfloat maxDepth = ctx->DrawBuffer->_DepthMaxF;
#define FixedToDepth(F) ((F) >> fixedToDepthShift)
#endif
EdgeT eMaj, eTop, eBot;
GLfloat oneOverArea;
const SWvertex *vMin, *vMid, *vMax; /* Y(vMin)<=Y(vMid)<=Y(vMax) */
GLfloat bf = SWRAST_CONTEXT(ctx)->_BackfaceSign;
const GLint snapMask = ~((FIXED_ONE / (1 << SUB_PIXEL_BITS)) - 1); /* for x/y coord snapping */
GLfixed vMin_fx, vMin_fy, vMid_fx, vMid_fy, vMax_fx, vMax_fy;
SWspan span;
(void) swrast;
INIT_SPAN(span, GL_POLYGON);
span.y = 0; /* silence warnings */
#ifdef INTERP_Z
(void) fixedToDepthShift;
#endif
/*
printf("%s()\n", __FUNCTION__);
printf(" %g, %g, %g\n",
v0->attrib[FRAG_ATTRIB_WPOS][0],
v0->attrib[FRAG_ATTRIB_WPOS][1],
v0->attrib[FRAG_ATTRIB_WPOS][2]);
printf(" %g, %g, %g\n",
v1->attrib[FRAG_ATTRIB_WPOS][0],
v1->attrib[FRAG_ATTRIB_WPOS][1],
v1->attrib[FRAG_ATTRIB_WPOS][2]);
printf(" %g, %g, %g\n",
v2->attrib[FRAG_ATTRIB_WPOS][0],
v2->attrib[FRAG_ATTRIB_WPOS][1],
v2->attrib[FRAG_ATTRIB_WPOS][2]);
*/
/* Compute fixed point x,y coords w/ half-pixel offsets and snapping.
* And find the order of the 3 vertices along the Y axis.
*/
{
const GLfixed fy0 = FloatToFixed(v0->attrib[FRAG_ATTRIB_WPOS][1] - 0.5F) & snapMask;
const GLfixed fy1 = FloatToFixed(v1->attrib[FRAG_ATTRIB_WPOS][1] - 0.5F) & snapMask;
const GLfixed fy2 = FloatToFixed(v2->attrib[FRAG_ATTRIB_WPOS][1] - 0.5F) & snapMask;
if (fy0 <= fy1) {
if (fy1 <= fy2) {
/* y0 <= y1 <= y2 */
vMin = v0; vMid = v1; vMax = v2;
vMin_fy = fy0; vMid_fy = fy1; vMax_fy = fy2;
}
else if (fy2 <= fy0) {
/* y2 <= y0 <= y1 */
vMin = v2; vMid = v0; vMax = v1;
vMin_fy = fy2; vMid_fy = fy0; vMax_fy = fy1;
}
else {
/* y0 <= y2 <= y1 */
vMin = v0; vMid = v2; vMax = v1;
vMin_fy = fy0; vMid_fy = fy2; vMax_fy = fy1;
bf = -bf;
}
}
else {
if (fy0 <= fy2) {
/* y1 <= y0 <= y2 */
vMin = v1; vMid = v0; vMax = v2;
vMin_fy = fy1; vMid_fy = fy0; vMax_fy = fy2;
bf = -bf;
}
else if (fy2 <= fy1) {
/* y2 <= y1 <= y0 */
vMin = v2; vMid = v1; vMax = v0;
vMin_fy = fy2; vMid_fy = fy1; vMax_fy = fy0;
bf = -bf;
}
else {
/* y1 <= y2 <= y0 */
vMin = v1; vMid = v2; vMax = v0;
vMin_fy = fy1; vMid_fy = fy2; vMax_fy = fy0;
}
}
/* fixed point X coords */
vMin_fx = FloatToFixed(vMin->attrib[FRAG_ATTRIB_WPOS][0] + 0.5F) & snapMask;
vMid_fx = FloatToFixed(vMid->attrib[FRAG_ATTRIB_WPOS][0] + 0.5F) & snapMask;
vMax_fx = FloatToFixed(vMax->attrib[FRAG_ATTRIB_WPOS][0] + 0.5F) & snapMask;
}
/* vertex/edge relationship */
eMaj.v0 = vMin; eMaj.v1 = vMax; /*TODO: .v1's not needed */
eTop.v0 = vMid; eTop.v1 = vMax;
eBot.v0 = vMin; eBot.v1 = vMid;
/* compute deltas for each edge: vertex[upper] - vertex[lower] */
eMaj.dx = FixedToFloat(vMax_fx - vMin_fx);
eMaj.dy = FixedToFloat(vMax_fy - vMin_fy);
eTop.dx = FixedToFloat(vMax_fx - vMid_fx);
eTop.dy = FixedToFloat(vMax_fy - vMid_fy);
eBot.dx = FixedToFloat(vMid_fx - vMin_fx);
eBot.dy = FixedToFloat(vMid_fy - vMin_fy);
/* compute area, oneOverArea and perform backface culling */
{
const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy;
if (IS_INF_OR_NAN(area) || area == 0.0F)
return;
if (area * bf * swrast->_BackfaceCullSign < 0.0)
return;
oneOverArea = 1.0F / area;
/* 0 = front, 1 = back */
span.facing = oneOverArea * bf > 0.0F;
}
/* Edge setup. For a triangle strip these could be reused... */
{
eMaj.fsy = FixedCeil(vMin_fy);
eMaj.lines = FixedToInt(FixedCeil(vMax_fy - eMaj.fsy));
if (eMaj.lines > 0) {
eMaj.dxdy = eMaj.dx / eMaj.dy;
eMaj.fdxdy = SignedFloatToFixed(eMaj.dxdy);
eMaj.adjy = (GLfloat) (eMaj.fsy - vMin_fy); /* SCALED! */
eMaj.fx0 = vMin_fx;
eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * eMaj.dxdy);
}
else {
return; /*CULLED*/
}
eTop.fsy = FixedCeil(vMid_fy);
eTop.lines = FixedToInt(FixedCeil(vMax_fy - eTop.fsy));
if (eTop.lines > 0) {
eTop.dxdy = eTop.dx / eTop.dy;
eTop.fdxdy = SignedFloatToFixed(eTop.dxdy);
eTop.adjy = (GLfloat) (eTop.fsy - vMid_fy); /* SCALED! */
eTop.fx0 = vMid_fx;
eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * eTop.dxdy);
}
eBot.fsy = FixedCeil(vMin_fy);
eBot.lines = FixedToInt(FixedCeil(vMid_fy - eBot.fsy));
if (eBot.lines > 0) {
eBot.dxdy = eBot.dx / eBot.dy;
eBot.fdxdy = SignedFloatToFixed(eBot.dxdy);
eBot.adjy = (GLfloat) (eBot.fsy - vMin_fy); /* SCALED! */
eBot.fx0 = vMin_fx;
eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * eBot.dxdy);
}
}
/*
* Conceptually, we view a triangle as two subtriangles
* separated by a perfectly horizontal line. The edge that is
* intersected by this line is one with maximal absolute dy; we
* call it a ``major'' edge. The other two edges are the
* ``top'' edge (for the upper subtriangle) and the ``bottom''
* edge (for the lower subtriangle). If either of these two
* edges is horizontal or very close to horizontal, the
* corresponding subtriangle might cover zero sample points;
* we take care to handle such cases, for performance as well
* as correctness.
*
* By stepping rasterization parameters along the major edge,
* we can avoid recomputing them at the discontinuity where
* the top and bottom edges meet. However, this forces us to
* be able to scan both left-to-right and right-to-left.
* Also, we must determine whether the major edge is at the
* left or right side of the triangle. We do this by
* computing the magnitude of the cross-product of the major
* and top edges. Since this magnitude depends on the sine of
* the angle between the two edges, its sign tells us whether
* we turn to the left or to the right when travelling along
* the major edge to the top edge, and from this we infer
* whether the major edge is on the left or the right.
*
* Serendipitously, this cross-product magnitude is also a
* value we need to compute the iteration parameter
* derivatives for the triangle, and it can be used to perform
* backface culling because its sign tells us whether the
* triangle is clockwise or counterclockwise. In this code we
* refer to it as ``area'' because it's also proportional to
* the pixel area of the triangle.
*/
{
GLint scan_from_left_to_right; /* true if scanning left-to-right */
/*
* Execute user-supplied setup code
*/
#ifdef SETUP_CODE
SETUP_CODE
#endif
scan_from_left_to_right = (oneOverArea < 0.0F);
/* compute d?/dx and d?/dy derivatives */
#ifdef INTERP_Z
span.interpMask |= SPAN_Z;
{
GLfloat eMaj_dz = vMax->attrib[FRAG_ATTRIB_WPOS][2] - vMin->attrib[FRAG_ATTRIB_WPOS][2];
GLfloat eBot_dz = vMid->attrib[FRAG_ATTRIB_WPOS][2] - vMin->attrib[FRAG_ATTRIB_WPOS][2];
span.attrStepX[FRAG_ATTRIB_WPOS][2] = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz);
if (span.attrStepX[FRAG_ATTRIB_WPOS][2] > maxDepth ||
span.attrStepX[FRAG_ATTRIB_WPOS][2] < -maxDepth) {
/* probably a sliver triangle */
span.attrStepX[FRAG_ATTRIB_WPOS][2] = 0.0;
span.attrStepY[FRAG_ATTRIB_WPOS][2] = 0.0;
}
else {
span.attrStepY[FRAG_ATTRIB_WPOS][2] = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx);
}
if (depthBits <= 16)
span.zStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_WPOS][2]);
else
span.zStep = (GLint) span.attrStepX[FRAG_ATTRIB_WPOS][2];
}
#endif
#ifdef INTERP_RGB
span.interpMask |= SPAN_RGBA;
if (ctx->Light.ShadeModel == GL_SMOOTH) {
GLfloat eMaj_dr = (GLfloat) (vMax->color[RCOMP] - vMin->color[RCOMP]);
GLfloat eBot_dr = (GLfloat) (vMid->color[RCOMP] - vMin->color[RCOMP]);
GLfloat eMaj_dg = (GLfloat) (vMax->color[GCOMP] - vMin->color[GCOMP]);
GLfloat eBot_dg = (GLfloat) (vMid->color[GCOMP] - vMin->color[GCOMP]);
GLfloat eMaj_db = (GLfloat) (vMax->color[BCOMP] - vMin->color[BCOMP]);
GLfloat eBot_db = (GLfloat) (vMid->color[BCOMP] - vMin->color[BCOMP]);
# ifdef INTERP_ALPHA
GLfloat eMaj_da = (GLfloat) (vMax->color[ACOMP] - vMin->color[ACOMP]);
GLfloat eBot_da = (GLfloat) (vMid->color[ACOMP] - vMin->color[ACOMP]);
# endif
span.attrStepX[FRAG_ATTRIB_COL0][0] = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
span.attrStepY[FRAG_ATTRIB_COL0][0] = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
span.attrStepX[FRAG_ATTRIB_COL0][1] = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
span.attrStepY[FRAG_ATTRIB_COL0][1] = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
span.attrStepX[FRAG_ATTRIB_COL0][2] = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
span.attrStepY[FRAG_ATTRIB_COL0][2] = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
span.redStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL0][0]);
span.greenStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL0][1]);
span.blueStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL0][2]);
# ifdef INTERP_ALPHA
span.attrStepX[FRAG_ATTRIB_COL0][3] = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
span.attrStepY[FRAG_ATTRIB_COL0][3] = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
span.alphaStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL0][3]);
# endif /* INTERP_ALPHA */
}
else {
ASSERT(ctx->Light.ShadeModel == GL_FLAT);
span.interpMask |= SPAN_FLAT;
span.attrStepX[FRAG_ATTRIB_COL0][0] = span.attrStepY[FRAG_ATTRIB_COL0][0] = 0.0F;
span.attrStepX[FRAG_ATTRIB_COL0][1] = span.attrStepY[FRAG_ATTRIB_COL0][1] = 0.0F;
span.attrStepX[FRAG_ATTRIB_COL0][2] = span.attrStepY[FRAG_ATTRIB_COL0][2] = 0.0F;
span.redStep = 0;
span.greenStep = 0;
span.blueStep = 0;
# ifdef INTERP_ALPHA
span.attrStepX[FRAG_ATTRIB_COL0][3] = span.attrStepY[FRAG_ATTRIB_COL0][3] = 0.0F;
span.alphaStep = 0;
# endif
}
#endif /* INTERP_RGB */
#ifdef INTERP_INT_TEX
{
GLfloat eMaj_ds = (vMax->attrib[FRAG_ATTRIB_TEX0][0] - vMin->attrib[FRAG_ATTRIB_TEX0][0]) * S_SCALE;
GLfloat eBot_ds = (vMid->attrib[FRAG_ATTRIB_TEX0][0] - vMin->attrib[FRAG_ATTRIB_TEX0][0]) * S_SCALE;
GLfloat eMaj_dt = (vMax->attrib[FRAG_ATTRIB_TEX0][1] - vMin->attrib[FRAG_ATTRIB_TEX0][1]) * T_SCALE;
GLfloat eBot_dt = (vMid->attrib[FRAG_ATTRIB_TEX0][1] - vMin->attrib[FRAG_ATTRIB_TEX0][1]) * T_SCALE;
span.attrStepX[FRAG_ATTRIB_TEX0][0] = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
span.attrStepY[FRAG_ATTRIB_TEX0][0] = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
span.attrStepX[FRAG_ATTRIB_TEX0][1] = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
span.attrStepY[FRAG_ATTRIB_TEX0][1] = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
span.intTexStep[0] = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_TEX0][0]);
span.intTexStep[1] = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_TEX0][1]);
}
#endif
#ifdef INTERP_ATTRIBS
{
/* attrib[FRAG_ATTRIB_WPOS][3] is 1/W */
const GLfloat wMax = vMax->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat wMin = vMin->attrib[FRAG_ATTRIB_WPOS][3];
const GLfloat wMid = vMid->attrib[FRAG_ATTRIB_WPOS][3];
{
const GLfloat eMaj_dw = wMax - wMin;
const GLfloat eBot_dw = wMid - wMin;
span.attrStepX[FRAG_ATTRIB_WPOS][3] = oneOverArea * (eMaj_dw * eBot.dy - eMaj.dy * eBot_dw);
span.attrStepY[FRAG_ATTRIB_WPOS][3] = oneOverArea * (eMaj.dx * eBot_dw - eMaj_dw * eBot.dx);
}
ATTRIB_LOOP_BEGIN
if (swrast->_InterpMode[attr] == GL_FLAT) {
ASSIGN_4V(span.attrStepX[attr], 0.0, 0.0, 0.0, 0.0);
ASSIGN_4V(span.attrStepY[attr], 0.0, 0.0, 0.0, 0.0);
}
else {
GLuint c;
for (c = 0; c < 4; c++) {
GLfloat eMaj_da = vMax->attrib[attr][c] * wMax - vMin->attrib[attr][c] * wMin;
GLfloat eBot_da = vMid->attrib[attr][c] * wMid - vMin->attrib[attr][c] * wMin;
span.attrStepX[attr][c] = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
span.attrStepY[attr][c] = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
}
}
ATTRIB_LOOP_END
}
#endif
/*
* We always sample at pixel centers. However, we avoid
* explicit half-pixel offsets in this code by incorporating
* the proper offset in each of x and y during the
* transformation to window coordinates.
*
* We also apply the usual rasterization rules to prevent
* cracks and overlaps. A pixel is considered inside a
* subtriangle if it meets all of four conditions: it is on or
* to the right of the left edge, strictly to the left of the
* right edge, on or below the top edge, and strictly above
* the bottom edge. (Some edges may be degenerate.)
*
* The following discussion assumes left-to-right scanning
* (that is, the major edge is on the left); the right-to-left
* case is a straightforward variation.
*
* We start by finding the half-integral y coordinate that is
* at or below the top of the triangle. This gives us the
* first scan line that could possibly contain pixels that are
* inside the triangle.
*
* Next we creep down the major edge until we reach that y,
* and compute the corresponding x coordinate on the edge.
* Then we find the half-integral x that lies on or just
* inside the edge. This is the first pixel that might lie in
* the interior of the triangle. (We won't know for sure
* until we check the other edges.)
*
* As we rasterize the triangle, we'll step down the major
* edge. For each step in y, we'll move an integer number
* of steps in x. There are two possible x step sizes, which
* we'll call the ``inner'' step (guaranteed to land on the
* edge or inside it) and the ``outer'' step (guaranteed to
* land on the edge or outside it). The inner and outer steps
* differ by one. During rasterization we maintain an error
* term that indicates our distance from the true edge, and
* select either the inner step or the outer step, whichever
* gets us to the first pixel that falls inside the triangle.
*
* All parameters (z, red, etc.) as well as the buffer
* addresses for color and z have inner and outer step values,
* so that we can increment them appropriately. This method
* eliminates the need to adjust parameters by creeping a
* sub-pixel amount into the triangle at each scanline.
*/
{
GLint subTriangle;
GLfixed fxLeftEdge = 0, fxRightEdge = 0;
GLfixed fdxLeftEdge = 0, fdxRightEdge = 0;
GLfixed fError = 0, fdError = 0;
#ifdef PIXEL_ADDRESS
PIXEL_TYPE *pRow = NULL;
GLint dPRowOuter = 0, dPRowInner; /* offset in bytes */
#endif
#ifdef INTERP_Z
# ifdef DEPTH_TYPE
struct gl_renderbuffer *zrb
= ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
DEPTH_TYPE *zRow = NULL;
GLint dZRowOuter = 0, dZRowInner; /* offset in bytes */
# endif
GLuint zLeft = 0;
GLfixed fdzOuter = 0, fdzInner;
#endif
#ifdef INTERP_RGB
GLint rLeft = 0, fdrOuter = 0, fdrInner;
GLint gLeft = 0, fdgOuter = 0, fdgInner;
GLint bLeft = 0, fdbOuter = 0, fdbInner;
#endif
#ifdef INTERP_ALPHA
GLint aLeft = 0, fdaOuter = 0, fdaInner;
#endif
#ifdef INTERP_INT_TEX
GLfixed sLeft=0, dsOuter=0, dsInner;
GLfixed tLeft=0, dtOuter=0, dtInner;
#endif
#ifdef INTERP_ATTRIBS
GLfloat wLeft = 0, dwOuter = 0, dwInner;
GLfloat attrLeft[FRAG_ATTRIB_MAX][4];
GLfloat daOuter[FRAG_ATTRIB_MAX][4], daInner[FRAG_ATTRIB_MAX][4];
#endif
for (subTriangle=0; subTriangle<=1; subTriangle++) {
EdgeT *eLeft, *eRight;
int setupLeft, setupRight;
int lines;
if (subTriangle==0) {
/* bottom half */
if (scan_from_left_to_right) {
eLeft = &eMaj;
eRight = &eBot;
lines = eRight->lines;
setupLeft = 1;
setupRight = 1;
}
else {
eLeft = &eBot;
eRight = &eMaj;
lines = eLeft->lines;
setupLeft = 1;
setupRight = 1;
}
}
else {
/* top half */
if (scan_from_left_to_right) {
eLeft = &eMaj;
eRight = &eTop;
lines = eRight->lines;
setupLeft = 0;
setupRight = 1;
}
else {
eLeft = &eTop;
eRight = &eMaj;
lines = eLeft->lines;
setupLeft = 1;
setupRight = 0;
}
if (lines == 0)
return;
}
if (setupLeft && eLeft->lines > 0) {
const SWvertex *vLower = eLeft->v0;
const GLfixed fsy = eLeft->fsy;
const GLfixed fsx = eLeft->fsx; /* no fractional part */
const GLfixed fx = FixedCeil(fsx); /* no fractional part */
const GLfixed adjx = (GLfixed) (fx - eLeft->fx0); /* SCALED! */
const GLfixed adjy = (GLfixed) eLeft->adjy; /* SCALED! */
GLint idxOuter;
GLfloat dxOuter;
GLfixed fdxOuter;
fError = fx - fsx - FIXED_ONE;
fxLeftEdge = fsx - FIXED_EPSILON;
fdxLeftEdge = eLeft->fdxdy;
fdxOuter = FixedFloor(fdxLeftEdge - FIXED_EPSILON);
fdError = fdxOuter - fdxLeftEdge + FIXED_ONE;
idxOuter = FixedToInt(fdxOuter);
dxOuter = (GLfloat) idxOuter;
span.y = FixedToInt(fsy);
/* silence warnings on some compilers */
(void) dxOuter;
(void) adjx;
(void) adjy;
(void) vLower;
#ifdef PIXEL_ADDRESS
{
pRow = (PIXEL_TYPE *) PIXEL_ADDRESS(FixedToInt(fxLeftEdge), span.y);
dPRowOuter = -((int)BYTES_PER_ROW) + idxOuter * sizeof(PIXEL_TYPE);
/* negative because Y=0 at bottom and increases upward */
}
#endif
/*
* Now we need the set of parameter (z, color, etc.) values at
* the point (fx, fsy). This gives us properly-sampled parameter
* values that we can step from pixel to pixel. Furthermore,
* although we might have intermediate results that overflow
* the normal parameter range when we step temporarily outside
* the triangle, we shouldn't overflow or underflow for any
* pixel that's actually inside the triangle.
*/
#ifdef INTERP_Z
{
GLfloat z0 = vLower->attrib[FRAG_ATTRIB_WPOS][2];
if (depthBits <= 16) {
/* interpolate fixed-pt values */
GLfloat tmp = (z0 * FIXED_SCALE
+ span.attrStepX[FRAG_ATTRIB_WPOS][2] * adjx
+ span.attrStepY[FRAG_ATTRIB_WPOS][2] * adjy) + FIXED_HALF;
if (tmp < MAX_GLUINT / 2)
zLeft = (GLfixed) tmp;
else
zLeft = MAX_GLUINT / 2;
fdzOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_WPOS][2] +
dxOuter * span.attrStepX[FRAG_ATTRIB_WPOS][2]);
}
else {
/* interpolate depth values w/out scaling */
zLeft = (GLuint) (z0 + span.attrStepX[FRAG_ATTRIB_WPOS][2] * FixedToFloat(adjx)
+ span.attrStepY[FRAG_ATTRIB_WPOS][2] * FixedToFloat(adjy));
fdzOuter = (GLint) (span.attrStepY[FRAG_ATTRIB_WPOS][2] +
dxOuter * span.attrStepX[FRAG_ATTRIB_WPOS][2]);
}
# ifdef DEPTH_TYPE
zRow = (DEPTH_TYPE *)
_swrast_pixel_address(zrb, FixedToInt(fxLeftEdge), span.y);
dZRowOuter = (ctx->DrawBuffer->Width + idxOuter) * sizeof(DEPTH_TYPE);
# endif
}
#endif
#ifdef INTERP_RGB
if (ctx->Light.ShadeModel == GL_SMOOTH) {
rLeft = (GLint)(ChanToFixed(vLower->color[RCOMP])
+ span.attrStepX[FRAG_ATTRIB_COL0][0] * adjx
+ span.attrStepY[FRAG_ATTRIB_COL0][0] * adjy) + FIXED_HALF;
gLeft = (GLint)(ChanToFixed(vLower->color[GCOMP])
+ span.attrStepX[FRAG_ATTRIB_COL0][1] * adjx
+ span.attrStepY[FRAG_ATTRIB_COL0][1] * adjy) + FIXED_HALF;
bLeft = (GLint)(ChanToFixed(vLower->color[BCOMP])
+ span.attrStepX[FRAG_ATTRIB_COL0][2] * adjx
+ span.attrStepY[FRAG_ATTRIB_COL0][2] * adjy) + FIXED_HALF;
fdrOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL0][0]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_COL0][0]);
fdgOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL0][1]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_COL0][1]);
fdbOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL0][2]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_COL0][2]);
# ifdef INTERP_ALPHA
aLeft = (GLint)(ChanToFixed(vLower->color[ACOMP])
+ span.attrStepX[FRAG_ATTRIB_COL0][3] * adjx
+ span.attrStepY[FRAG_ATTRIB_COL0][3] * adjy) + FIXED_HALF;
fdaOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL0][3]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_COL0][3]);
# endif
}
else {
ASSERT(ctx->Light.ShadeModel == GL_FLAT);
rLeft = ChanToFixed(v2->color[RCOMP]);
gLeft = ChanToFixed(v2->color[GCOMP]);
bLeft = ChanToFixed(v2->color[BCOMP]);
fdrOuter = fdgOuter = fdbOuter = 0;
# ifdef INTERP_ALPHA
aLeft = ChanToFixed(v2->color[ACOMP]);
fdaOuter = 0;
# endif
}
#endif /* INTERP_RGB */
#ifdef INTERP_INT_TEX
{
GLfloat s0, t0;
s0 = vLower->attrib[FRAG_ATTRIB_TEX0][0] * S_SCALE;
sLeft = (GLfixed)(s0 * FIXED_SCALE + span.attrStepX[FRAG_ATTRIB_TEX0][0] * adjx
+ span.attrStepY[FRAG_ATTRIB_TEX0][0] * adjy) + FIXED_HALF;
dsOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_TEX0][0]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_TEX0][0]);
t0 = vLower->attrib[FRAG_ATTRIB_TEX0][1] * T_SCALE;
tLeft = (GLfixed)(t0 * FIXED_SCALE + span.attrStepX[FRAG_ATTRIB_TEX0][1] * adjx
+ span.attrStepY[FRAG_ATTRIB_TEX0][1] * adjy) + FIXED_HALF;
dtOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_TEX0][1]
+ dxOuter * span.attrStepX[FRAG_ATTRIB_TEX0][1]);
}
#endif
#ifdef INTERP_ATTRIBS
{
const GLuint attr = FRAG_ATTRIB_WPOS;
wLeft = vLower->attrib[FRAG_ATTRIB_WPOS][3]
+ (span.attrStepX[attr][3] * adjx
+ span.attrStepY[attr][3] * adjy) * (1.0F/FIXED_SCALE);
dwOuter = span.attrStepY[attr][3] + dxOuter * span.attrStepX[attr][3];
}
ATTRIB_LOOP_BEGIN
const GLfloat invW = vLower->attrib[FRAG_ATTRIB_WPOS][3];
if (swrast->_InterpMode[attr] == GL_FLAT) {
GLuint c;
for (c = 0; c < 4; c++) {
attrLeft[attr][c] = v2->attrib[attr][c] * invW;
daOuter[attr][c] = 0.0;
}
}
else {
GLuint c;
for (c = 0; c < 4; c++) {
const GLfloat a = vLower->attrib[attr][c] * invW;
attrLeft[attr][c] = a + ( span.attrStepX[attr][c] * adjx
+ span.attrStepY[attr][c] * adjy) * (1.0F/FIXED_SCALE);
daOuter[attr][c] = span.attrStepY[attr][c] + dxOuter * span.attrStepX[attr][c];
}
}
ATTRIB_LOOP_END
#endif
} /*if setupLeft*/
if (setupRight && eRight->lines>0) {
fxRightEdge = eRight->fsx - FIXED_EPSILON;
fdxRightEdge = eRight->fdxdy;
}
if (lines==0) {
continue;
}
/* Rasterize setup */
#ifdef PIXEL_ADDRESS
dPRowInner = dPRowOuter + sizeof(PIXEL_TYPE);
#endif
#ifdef INTERP_Z
# ifdef DEPTH_TYPE
dZRowInner = dZRowOuter + sizeof(DEPTH_TYPE);
# endif
fdzInner = fdzOuter + span.zStep;
#endif
#ifdef INTERP_RGB
fdrInner = fdrOuter + span.redStep;
fdgInner = fdgOuter + span.greenStep;
fdbInner = fdbOuter + span.blueStep;
#endif
#ifdef INTERP_ALPHA
fdaInner = fdaOuter + span.alphaStep;
#endif
#ifdef INTERP_INT_TEX
dsInner = dsOuter + span.intTexStep[0];
dtInner = dtOuter + span.intTexStep[1];
#endif
#ifdef INTERP_ATTRIBS
dwInner = dwOuter + span.attrStepX[FRAG_ATTRIB_WPOS][3];
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
daInner[attr][c] = daOuter[attr][c] + span.attrStepX[attr][c];
}
ATTRIB_LOOP_END
#endif
while (lines > 0) {
/* initialize the span interpolants to the leftmost value */
/* ff = fixed-pt fragment */
const GLint right = FixedToInt(fxRightEdge);
span.x = FixedToInt(fxLeftEdge);
if (right <= span.x)
span.end = 0;
else
span.end = right - span.x;
#ifdef INTERP_Z
span.z = zLeft;
#endif
#ifdef INTERP_RGB
span.red = rLeft;
span.green = gLeft;
span.blue = bLeft;
#endif
#ifdef INTERP_ALPHA
span.alpha = aLeft;
#endif
#ifdef INTERP_INT_TEX
span.intTex[0] = sLeft;
span.intTex[1] = tLeft;
#endif
#ifdef INTERP_ATTRIBS
span.attrStart[FRAG_ATTRIB_WPOS][3] = wLeft;
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
span.attrStart[attr][c] = attrLeft[attr][c];
}
ATTRIB_LOOP_END
#endif
/* This is where we actually generate fragments */
/* XXX the test for span.y > 0 _shouldn't_ be needed but
* it fixes a problem on 64-bit Opterons (bug 4842).
*/
if (span.end > 0 && span.y >= 0) {
const GLint len = span.end - 1;
(void) len;
#ifdef INTERP_RGB
CLAMP_INTERPOLANT(red, redStep, len);
CLAMP_INTERPOLANT(green, greenStep, len);
CLAMP_INTERPOLANT(blue, blueStep, len);
#endif
#ifdef INTERP_ALPHA
CLAMP_INTERPOLANT(alpha, alphaStep, len);
#endif
{
RENDER_SPAN( span );
}
}
/*
* Advance to the next scan line. Compute the
* new edge coordinates, and adjust the
* pixel-center x coordinate so that it stays
* on or inside the major edge.
*/
span.y++;
lines--;
fxLeftEdge += fdxLeftEdge;
fxRightEdge += fdxRightEdge;
fError += fdError;
if (fError >= 0) {
fError -= FIXED_ONE;
#ifdef PIXEL_ADDRESS
pRow = (PIXEL_TYPE *) ((GLubyte *) pRow + dPRowOuter);
#endif
#ifdef INTERP_Z
# ifdef DEPTH_TYPE
zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowOuter);
# endif
zLeft += fdzOuter;
#endif
#ifdef INTERP_RGB
rLeft += fdrOuter;
gLeft += fdgOuter;
bLeft += fdbOuter;
#endif
#ifdef INTERP_ALPHA
aLeft += fdaOuter;
#endif
#ifdef INTERP_INT_TEX
sLeft += dsOuter;
tLeft += dtOuter;
#endif
#ifdef INTERP_ATTRIBS
wLeft += dwOuter;
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
attrLeft[attr][c] += daOuter[attr][c];
}
ATTRIB_LOOP_END
#endif
}
else {
#ifdef PIXEL_ADDRESS
pRow = (PIXEL_TYPE *) ((GLubyte *) pRow + dPRowInner);
#endif
#ifdef INTERP_Z
# ifdef DEPTH_TYPE
zRow = (DEPTH_TYPE *) ((GLubyte *) zRow + dZRowInner);
# endif
zLeft += fdzInner;
#endif
#ifdef INTERP_RGB
rLeft += fdrInner;
gLeft += fdgInner;
bLeft += fdbInner;
#endif
#ifdef INTERP_ALPHA
aLeft += fdaInner;
#endif
#ifdef INTERP_INT_TEX
sLeft += dsInner;
tLeft += dtInner;
#endif
#ifdef INTERP_ATTRIBS
wLeft += dwInner;
ATTRIB_LOOP_BEGIN
GLuint c;
for (c = 0; c < 4; c++) {
attrLeft[attr][c] += daInner[attr][c];
}
ATTRIB_LOOP_END
#endif
}
} /*while lines>0*/
} /* for subTriangle */
}
}
}
#undef SETUP_CODE
#undef RENDER_SPAN
#undef PIXEL_TYPE
#undef BYTES_PER_ROW
#undef PIXEL_ADDRESS
#undef DEPTH_TYPE
#undef INTERP_Z
#undef INTERP_RGB
#undef INTERP_ALPHA
#undef INTERP_INT_TEX
#undef INTERP_ATTRIBS
#undef S_SCALE
#undef T_SCALE
#undef FixedToDepth
#undef NAME