+++ /dev/null
-/*
- * 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;
- }
-
- /* 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_COL][0] = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr);
- span.attrStepY[FRAG_ATTRIB_COL][0] = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx);
- span.attrStepX[FRAG_ATTRIB_COL][1] = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg);
- span.attrStepY[FRAG_ATTRIB_COL][1] = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx);
- span.attrStepX[FRAG_ATTRIB_COL][2] = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db);
- span.attrStepY[FRAG_ATTRIB_COL][2] = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx);
- span.redStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL][0]);
- span.greenStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL][1]);
- span.blueStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL][2]);
-# ifdef INTERP_ALPHA
- span.attrStepX[FRAG_ATTRIB_COL][3] = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da);
- span.attrStepY[FRAG_ATTRIB_COL][3] = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx);
- span.alphaStep = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_COL][3]);
-# endif /* INTERP_ALPHA */
- }
- else {
- ASSERT(ctx->Light.ShadeModel == GL_FLAT);
- span.interpMask |= SPAN_FLAT;
- span.attrStepX[FRAG_ATTRIB_COL][0] = span.attrStepY[FRAG_ATTRIB_COL][0] = 0.0F;
- span.attrStepX[FRAG_ATTRIB_COL][1] = span.attrStepY[FRAG_ATTRIB_COL][1] = 0.0F;
- span.attrStepX[FRAG_ATTRIB_COL][2] = span.attrStepY[FRAG_ATTRIB_COL][2] = 0.0F;
- span.redStep = 0;
- span.greenStep = 0;
- span.blueStep = 0;
-# ifdef INTERP_ALPHA
- span.attrStepX[FRAG_ATTRIB_COL][3] = span.attrStepY[FRAG_ATTRIB_COL][3] = 0.0F;
- span.alphaStep = 0;
-# endif
- }
-#endif /* INTERP_RGB */
-#ifdef INTERP_INT_TEX
- {
- GLfloat eMaj_ds = (vMax->attrib[FRAG_ATTRIB_TEX][0] - vMin->attrib[FRAG_ATTRIB_TEX][0]) * S_SCALE;
- GLfloat eBot_ds = (vMid->attrib[FRAG_ATTRIB_TEX][0] - vMin->attrib[FRAG_ATTRIB_TEX][0]) * S_SCALE;
- GLfloat eMaj_dt = (vMax->attrib[FRAG_ATTRIB_TEX][1] - vMin->attrib[FRAG_ATTRIB_TEX][1]) * T_SCALE;
- GLfloat eBot_dt = (vMid->attrib[FRAG_ATTRIB_TEX][1] - vMin->attrib[FRAG_ATTRIB_TEX][1]) * T_SCALE;
- span.attrStepX[FRAG_ATTRIB_TEX][0] = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds);
- span.attrStepY[FRAG_ATTRIB_TEX][0] = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx);
- span.attrStepX[FRAG_ATTRIB_TEX][1] = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt);
- span.attrStepY[FRAG_ATTRIB_TEX][1] = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx);
- span.intTexStep[0] = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_TEX][0]);
- span.intTexStep[1] = SignedFloatToFixed(span.attrStepX[FRAG_ATTRIB_TEX][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_COL][0] * adjx
- + span.attrStepY[FRAG_ATTRIB_COL][0] * adjy) + FIXED_HALF;
- gLeft = (GLint)(ChanToFixed(vLower->color[GCOMP])
- + span.attrStepX[FRAG_ATTRIB_COL][1] * adjx
- + span.attrStepY[FRAG_ATTRIB_COL][1] * adjy) + FIXED_HALF;
- bLeft = (GLint)(ChanToFixed(vLower->color[BCOMP])
- + span.attrStepX[FRAG_ATTRIB_COL][2] * adjx
- + span.attrStepY[FRAG_ATTRIB_COL][2] * adjy) + FIXED_HALF;
- fdrOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL][0]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_COL][0]);
- fdgOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL][1]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_COL][1]);
- fdbOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL][2]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_COL][2]);
-# ifdef INTERP_ALPHA
- aLeft = (GLint)(ChanToFixed(vLower->color[ACOMP])
- + span.attrStepX[FRAG_ATTRIB_COL][3] * adjx
- + span.attrStepY[FRAG_ATTRIB_COL][3] * adjy) + FIXED_HALF;
- fdaOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_COL][3]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_COL][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_TEX][0] * S_SCALE;
- sLeft = (GLfixed)(s0 * FIXED_SCALE + span.attrStepX[FRAG_ATTRIB_TEX][0] * adjx
- + span.attrStepY[FRAG_ATTRIB_TEX][0] * adjy) + FIXED_HALF;
- dsOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_TEX][0]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_TEX][0]);
-
- t0 = vLower->attrib[FRAG_ATTRIB_TEX][1] * T_SCALE;
- tLeft = (GLfixed)(t0 * FIXED_SCALE + span.attrStepX[FRAG_ATTRIB_TEX][1] * adjx
- + span.attrStepY[FRAG_ATTRIB_TEX][1] * adjy) + FIXED_HALF;
- dtOuter = SignedFloatToFixed(span.attrStepY[FRAG_ATTRIB_TEX][1]
- + dxOuter * span.attrStepX[FRAG_ATTRIB_TEX][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
projects / reactos.git / blobdiff