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Diffstat (limited to 'mesalib/src/mesa/swrast/s_tritemp.h')
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1 files changed, 979 insertions, 0 deletions
diff --git a/mesalib/src/mesa/swrast/s_tritemp.h b/mesalib/src/mesa/swrast/s_tritemp.h new file mode 100644 index 000000000..8e3c5b5ee --- /dev/null +++ b/mesalib/src/mesa/swrast/s_tritemp.h @@ -0,0 +1,979 @@ +/* + * 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_INDEX - if defined, interpolate color index 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(GLcontext *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 */ +#ifdef INTERP_INDEX + GLfloat didx, didy; +#endif + + /* + * 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_INDEX + span.interpMask |= SPAN_INDEX; + if (ctx->Light.ShadeModel == GL_SMOOTH) { + GLfloat eMaj_di = vMax->attrib[FRAG_ATTRIB_CI][0] - vMin->attrib[FRAG_ATTRIB_CI][0]; + GLfloat eBot_di = vMid->attrib[FRAG_ATTRIB_CI][0] - vMin->attrib[FRAG_ATTRIB_CI][0]; + didx = oneOverArea * (eMaj_di * eBot.dy - eMaj.dy * eBot_di); + didy = oneOverArea * (eMaj.dx * eBot_di - eMaj_di * eBot.dx); + span.indexStep = SignedFloatToFixed(didx); + } + else { + span.interpMask |= SPAN_FLAT; + didx = didy = 0.0F; + span.indexStep = 0; + } +#endif +#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_INDEX + GLfixed iLeft=0, diOuter=0, diInner; +#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 *) + zrb->GetPointer(ctx, 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_INDEX + if (ctx->Light.ShadeModel == GL_SMOOTH) { + iLeft = (GLfixed)(vLower->attrib[FRAG_ATTRIB_CI][0] * FIXED_SCALE + + didx * adjx + didy * adjy) + FIXED_HALF; + diOuter = SignedFloatToFixed(didy + dxOuter * didx); + } + else { + ASSERT(ctx->Light.ShadeModel == GL_FLAT); + iLeft = FloatToFixed(v2->attrib[FRAG_ATTRIB_CI][0]); + diOuter = 0; + } +#endif +#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_INDEX + diInner = diOuter + span.indexStep; +#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_INDEX + span.index = iLeft; +#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 +#ifdef INTERP_INDEX + CLAMP_INTERPOLANT(index, indexStep, 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_INDEX + iLeft += diOuter; +#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_INDEX + iLeft += diInner; +#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_INDEX +#undef INTERP_INT_TEX +#undef INTERP_ATTRIBS + +#undef S_SCALE +#undef T_SCALE + +#undef FixedToDepth + +#undef NAME |