| /* |
| * 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 |
