/* $Id: tritemp.h,v 1.2 2000-05-23 20:34:58 jeroen Exp $ */ /* * Mesa 3-D graphics library * Version: 3.3 * * Copyright (C) 1999 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 interplated across the triangle: * INTERP_Z - if defined, interpolate Z values * INTERP_RGB - if defined, interpolate RGB values * INTERP_SPEC - if defined, interpolate specular RGB values * INTERP_ALPHA - if defined, interpolate Alpha values * INTERP_INDEX - if defined, interpolate color index values * INTERP_INT_ST - if defined, interpolate integer ST texcoords * (fast, simple 2-D texture mapping) * INTERP_STUV - if defined, interpolate set 0 float STRQ texcoords * NOTE: OpenGL STRQ = Mesa STUV (R was taken for red) * INTERP_STUV1 - if defined, interpolate set 1 float STRQ texcoords * * 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: * 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: * INNER_LOOP(LEFT,RIGHT,Y) - code to write a span of pixels. * Something like: * * for (x=LEFT; xfy to fsy, scaled */ GLint lines; /* number of lines to be sampled on this edge */ GLfixed fx0; /* fixed pt X of lower endpoint */ } EdgeT; #ifdef INTERP_Z const GLint depthBits = ctx->Visual->DepthBits; const GLint fixedToDepthShift = depthBits <= 16 ? FIXED_SHIFT : 0; const GLfloat maxDepth = ctx->Visual->DepthMaxF; #define FixedToDepth(F) ((F) >> fixedToDepthShift) #endif const struct vertex_buffer *VB = ctx->VB; EdgeT eMaj, eTop, eBot; GLfloat oneOverArea; int vMin, vMid, vMax; /* vertex indexes: Y(vMin)<=Y(vMid)<=Y(vMax) */ float bf = ctx->backface_sign; /* find the order of the 3 vertices along the Y axis */ { GLfloat y0 = VB->Win.data[v0][1]; GLfloat y1 = VB->Win.data[v1][1]; GLfloat y2 = VB->Win.data[v2][1]; if (y0<=y1) { if (y1<=y2) { vMin = v0; vMid = v1; vMax = v2; /* y0<=y1<=y2 */ } else if (y2<=y0) { vMin = v2; vMid = v0; vMax = v1; /* y2<=y0<=y1 */ } else { vMin = v0; vMid = v2; vMax = v1; bf = -bf; /* y0<=y2<=y1 */ } } else { if (y0<=y2) { vMin = v1; vMid = v0; vMax = v2; bf = -bf; /* y1<=y0<=y2 */ } else if (y2<=y1) { vMin = v2; vMid = v1; vMax = v0; bf = -bf; /* y2<=y1<=y0 */ } else { vMin = v1; vMid = v2; vMax = v0; /* y1<=y2<=y0 */ } } } /* 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[v1] - vertex[v0] */ eMaj.dx = VB->Win.data[vMax][0] - VB->Win.data[vMin][0]; eMaj.dy = VB->Win.data[vMax][1] - VB->Win.data[vMin][1]; eTop.dx = VB->Win.data[vMax][0] - VB->Win.data[vMid][0]; eTop.dy = VB->Win.data[vMax][1] - VB->Win.data[vMid][1]; eBot.dx = VB->Win.data[vMid][0] - VB->Win.data[vMin][0]; eBot.dy = VB->Win.data[vMid][1] - VB->Win.data[vMin][1]; /* compute oneOverArea */ { const GLfloat area = eMaj.dx * eBot.dy - eBot.dx * eMaj.dy; /* Do backface culling */ if (area * bf < 0 || area * area < .0025) return; oneOverArea = 1.0F / area; } /* Edge setup. For a triangle strip these could be reused... */ { /* fixed point Y coordinates */ GLfixed vMin_fx = FloatToFixed(VB->Win.data[vMin][0] + 0.5F); GLfixed vMin_fy = FloatToFixed(VB->Win.data[vMin][1] - 0.5F); GLfixed vMid_fx = FloatToFixed(VB->Win.data[vMid][0] + 0.5F); GLfixed vMid_fy = FloatToFixed(VB->Win.data[vMid][1] - 0.5F); GLfixed vMax_fy = FloatToFixed(VB->Win.data[vMax][1] - 0.5F); eMaj.fsy = FixedCeil(vMin_fy); eMaj.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eMaj.fsy); if (eMaj.lines > 0) { GLfloat dxdy = eMaj.dx / eMaj.dy; eMaj.fdxdy = SignedFloatToFixed(dxdy); eMaj.adjy = (GLfloat) (eMaj.fsy - vMin_fy); /* SCALED! */ eMaj.fx0 = vMin_fx; eMaj.fsx = eMaj.fx0 + (GLfixed) (eMaj.adjy * dxdy); } else { return; /*CULLED*/ } eTop.fsy = FixedCeil(vMid_fy); eTop.lines = FixedToInt(vMax_fy + FIXED_ONE - FIXED_EPSILON - eTop.fsy); if (eTop.lines > 0) { GLfloat dxdy = eTop.dx / eTop.dy; eTop.fdxdy = SignedFloatToFixed(dxdy); eTop.adjy = (GLfloat) (eTop.fsy - vMid_fy); /* SCALED! */ eTop.fx0 = vMid_fx; eTop.fsx = eTop.fx0 + (GLfixed) (eTop.adjy * dxdy); } eBot.fsy = FixedCeil(vMin_fy); eBot.lines = FixedToInt(vMid_fy + FIXED_ONE - FIXED_EPSILON - eBot.fsy); if (eBot.lines > 0) { GLfloat dxdy = eBot.dx / eBot.dy; eBot.fdxdy = SignedFloatToFixed(dxdy); eBot.adjy = (GLfloat) (eBot.fsy - vMin_fy); /* SCALED! */ eBot.fx0 = vMin_fx; eBot.fsx = eBot.fx0 + (GLfixed) (eBot.adjy * 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 ltor; /* true if scanning left-to-right */ #ifdef INTERP_Z GLfloat dzdx, dzdy; GLfixed fdzdx; #endif #ifdef INTERP_RGB GLfloat drdx, drdy; GLfixed fdrdx; GLfloat dgdx, dgdy; GLfixed fdgdx; GLfloat dbdx, dbdy; GLfixed fdbdx; #endif #ifdef INTERP_SPEC GLfloat dsrdx, dsrdy; GLfixed fdsrdx; GLfloat dsgdx, dsgdy; GLfixed fdsgdx; GLfloat dsbdx, dsbdy; GLfixed fdsbdx; #endif #ifdef INTERP_ALPHA GLfloat dadx, dady; GLfixed fdadx; #endif #ifdef INTERP_INDEX GLfloat didx, didy; GLfixed fdidx; #endif #ifdef INTERP_INT_ST GLfloat dsdx, dsdy; GLfixed fdsdx; GLfloat dtdx, dtdy; GLfixed fdtdx; #endif #ifdef INTERP_STUV GLfloat dsdx, dsdy; GLfloat dtdx, dtdy; GLfloat dudx, dudy; GLfloat dvdx, dvdy; #endif #ifdef INTERP_STUV1 GLfloat ds1dx, ds1dy; GLfloat dt1dx, dt1dy; GLfloat du1dx, du1dy; GLfloat dv1dx, dv1dy; #endif /* * Execute user-supplied setup code */ #ifdef SETUP_CODE SETUP_CODE #endif ltor = (oneOverArea < 0.0F); /* compute d?/dx and d?/dy derivatives */ #ifdef INTERP_Z { GLfloat eMaj_dz, eBot_dz; eMaj_dz = VB->Win.data[vMax][2] - VB->Win.data[vMin][2]; eBot_dz = VB->Win.data[vMid][2] - VB->Win.data[vMin][2]; dzdx = oneOverArea * (eMaj_dz * eBot.dy - eMaj.dy * eBot_dz); if (dzdx > maxDepth || dzdx < -maxDepth) { /* probably a sliver triangle */ dzdx = 0.0; dzdy = 0.0; } else { dzdy = oneOverArea * (eMaj.dx * eBot_dz - eMaj_dz * eBot.dx); } if (depthBits <= 16) fdzdx = SignedFloatToFixed(dzdx); else fdzdx = (GLint) dzdx; } #endif #ifdef INTERP_RGB { GLfloat eMaj_dr, eBot_dr; eMaj_dr = (GLint) VB->ColorPtr->data[vMax][0] - (GLint) VB->ColorPtr->data[vMin][0]; eBot_dr = (GLint) VB->ColorPtr->data[vMid][0] - (GLint) VB->ColorPtr->data[vMin][0]; drdx = oneOverArea * (eMaj_dr * eBot.dy - eMaj.dy * eBot_dr); fdrdx = SignedFloatToFixed(drdx); drdy = oneOverArea * (eMaj.dx * eBot_dr - eMaj_dr * eBot.dx); } { GLfloat eMaj_dg, eBot_dg; eMaj_dg = (GLint) VB->ColorPtr->data[vMax][1] - (GLint) VB->ColorPtr->data[vMin][1]; eBot_dg = (GLint) VB->ColorPtr->data[vMid][1] - (GLint) VB->ColorPtr->data[vMin][1]; dgdx = oneOverArea * (eMaj_dg * eBot.dy - eMaj.dy * eBot_dg); fdgdx = SignedFloatToFixed(dgdx); dgdy = oneOverArea * (eMaj.dx * eBot_dg - eMaj_dg * eBot.dx); } { GLfloat eMaj_db, eBot_db; eMaj_db = (GLint) VB->ColorPtr->data[vMax][2] - (GLint) VB->ColorPtr->data[vMin][2]; eBot_db = (GLint) VB->ColorPtr->data[vMid][2] - (GLint) VB->ColorPtr->data[vMin][2]; dbdx = oneOverArea * (eMaj_db * eBot.dy - eMaj.dy * eBot_db); fdbdx = SignedFloatToFixed(dbdx); dbdy = oneOverArea * (eMaj.dx * eBot_db - eMaj_db * eBot.dx); } #endif #ifdef INTERP_SPEC { GLfloat eMaj_dsr, eBot_dsr; eMaj_dsr = (GLint) VB->Specular[vMax][0] - (GLint) VB->Specular[vMin][0]; eBot_dsr = (GLint) VB->Specular[vMid][0] - (GLint) VB->Specular[vMin][0]; dsrdx = oneOverArea * (eMaj_dsr * eBot.dy - eMaj.dy * eBot_dsr); fdsrdx = SignedFloatToFixed(dsrdx); dsrdy = oneOverArea * (eMaj.dx * eBot_dsr - eMaj_dsr * eBot.dx); } { GLfloat eMaj_dsg, eBot_dsg; eMaj_dsg = (GLint) VB->Specular[vMax][1] - (GLint) VB->Specular[vMin][1]; eBot_dsg = (GLint) VB->Specular[vMid][1] - (GLint) VB->Specular[vMin][1]; dsgdx = oneOverArea * (eMaj_dsg * eBot.dy - eMaj.dy * eBot_dsg); fdsgdx = SignedFloatToFixed(dsgdx); dsgdy = oneOverArea * (eMaj.dx * eBot_dsg - eMaj_dsg * eBot.dx); } { GLfloat eMaj_dsb, eBot_dsb; eMaj_dsb = (GLint) VB->Specular[vMax][2] - (GLint) VB->Specular[vMin][2]; eBot_dsb = (GLint) VB->Specular[vMid][2] - (GLint) VB->Specular[vMin][2]; dsbdx = oneOverArea * (eMaj_dsb * eBot.dy - eMaj.dy * eBot_dsb); fdsbdx = SignedFloatToFixed(dsbdx); dsbdy = oneOverArea * (eMaj.dx * eBot_dsb - eMaj_dsb * eBot.dx); } #endif #ifdef INTERP_ALPHA { GLfloat eMaj_da, eBot_da; eMaj_da = (GLint) VB->ColorPtr->data[vMax][3] - (GLint) VB->ColorPtr->data[vMin][3]; eBot_da = (GLint) VB->ColorPtr->data[vMid][3] - (GLint) VB->ColorPtr->data[vMin][3]; dadx = oneOverArea * (eMaj_da * eBot.dy - eMaj.dy * eBot_da); fdadx = SignedFloatToFixed(dadx); dady = oneOverArea * (eMaj.dx * eBot_da - eMaj_da * eBot.dx); } #endif #ifdef INTERP_INDEX { GLfloat eMaj_di, eBot_di; eMaj_di = (GLint) VB->IndexPtr->data[vMax] - (GLint) VB->IndexPtr->data[vMin]; eBot_di = (GLint) VB->IndexPtr->data[vMid] - (GLint) VB->IndexPtr->data[vMin]; didx = oneOverArea * (eMaj_di * eBot.dy - eMaj.dy * eBot_di); fdidx = SignedFloatToFixed(didx); didy = oneOverArea * (eMaj.dx * eBot_di - eMaj_di * eBot.dx); } #endif #ifdef INTERP_INT_ST { GLfloat eMaj_ds, eBot_ds; eMaj_ds = (VB->TexCoordPtr[0]->data[vMax][0] - VB->TexCoordPtr[0]->data[vMin][0]) * S_SCALE; eBot_ds = (VB->TexCoordPtr[0]->data[vMid][0] - VB->TexCoordPtr[0]->data[vMin][0]) * S_SCALE; dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds); fdsdx = SignedFloatToFixed(dsdx); dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx); } if (VB->TexCoordPtr[0]->size > 1) { GLfloat eMaj_dt, eBot_dt; eMaj_dt = (VB->TexCoordPtr[0]->data[vMax][1] - VB->TexCoordPtr[0]->data[vMin][1]) * T_SCALE; eBot_dt = (VB->TexCoordPtr[0]->data[vMid][1] - VB->TexCoordPtr[0]->data[vMin][1]) * T_SCALE; dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt); fdtdx = SignedFloatToFixed(dtdx); dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx); } else { dtdx = 0; fdtdx = SignedFloatToFixed(dtdx); dtdy = 0; } #endif #ifdef INTERP_STUV { GLfloat wMax = VB->Win.data[vMax][3]; GLfloat wMin = VB->Win.data[vMin][3]; GLfloat wMid = VB->Win.data[vMid][3]; GLfloat eMaj_ds, eBot_ds; GLfloat eMaj_dt, eBot_dt; GLfloat eMaj_du, eBot_du; GLfloat eMaj_dv, eBot_dv; eMaj_ds = VB->TexCoordPtr[0]->data[vMax][0]*wMax - VB->TexCoordPtr[0]->data[vMin][0]*wMin; eBot_ds = VB->TexCoordPtr[0]->data[vMid][0]*wMid - VB->TexCoordPtr[0]->data[vMin][0]*wMin; dsdx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds); dsdy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx); if (VB->TexCoordPtr[0]->size > 1) { eMaj_dt = VB->TexCoordPtr[0]->data[vMax][1]*wMax - VB->TexCoordPtr[0]->data[vMin][1]*wMin; eBot_dt = VB->TexCoordPtr[0]->data[vMid][1]*wMid - VB->TexCoordPtr[0]->data[vMin][1]*wMin; dtdx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt); dtdy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx); } else { dtdx = 0; dtdy = 0; } if (VB->TexCoordPtr[0]->size > 2) { eMaj_du = VB->TexCoordPtr[0]->data[vMax][2]*wMax - VB->TexCoordPtr[0]->data[vMin][2]*wMin; eBot_du = VB->TexCoordPtr[0]->data[vMid][2]*wMid - VB->TexCoordPtr[0]->data[vMin][2]*wMin; dudx = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du); dudy = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx); } else { dudx = 0; dudy = 0; } if (VB->TexCoordPtr[0]->size > 3) { eMaj_dv = VB->TexCoordPtr[0]->data[vMax][3]*wMax - VB->TexCoordPtr[0]->data[vMin][3]*wMin; eBot_dv = VB->TexCoordPtr[0]->data[vMid][3]*wMid - VB->TexCoordPtr[0]->data[vMin][3]*wMin; dvdx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv); dvdy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx); } else { eMaj_dv = wMax - wMin; eBot_dv = wMid - wMin; dvdx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv); dvdy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx); } } #endif #ifdef INTERP_STUV1 { GLfloat wMax = VB->Win.data[vMax][3]; GLfloat wMin = VB->Win.data[vMin][3]; GLfloat wMid = VB->Win.data[vMid][3]; GLfloat eMaj_ds, eBot_ds; GLfloat eMaj_dt, eBot_dt; GLfloat eMaj_du, eBot_du; GLfloat eMaj_dv, eBot_dv; eMaj_ds = VB->TexCoordPtr[1]->data[vMax][0]*wMax - VB->TexCoordPtr[1]->data[vMin][0]*wMin; eBot_ds = VB->TexCoordPtr[1]->data[vMid][0]*wMid - VB->TexCoordPtr[1]->data[vMin][0]*wMin; ds1dx = oneOverArea * (eMaj_ds * eBot.dy - eMaj.dy * eBot_ds); ds1dy = oneOverArea * (eMaj.dx * eBot_ds - eMaj_ds * eBot.dx); if (VB->TexCoordPtr[1]->size > 1) { eMaj_dt = VB->TexCoordPtr[1]->data[vMax][1]*wMax - VB->TexCoordPtr[1]->data[vMin][1]*wMin; eBot_dt = VB->TexCoordPtr[1]->data[vMid][1]*wMid - VB->TexCoordPtr[1]->data[vMin][1]*wMin; dt1dx = oneOverArea * (eMaj_dt * eBot.dy - eMaj.dy * eBot_dt); dt1dy = oneOverArea * (eMaj.dx * eBot_dt - eMaj_dt * eBot.dx); } else { dt1dx = 0; dt1dy = 0; } if (VB->TexCoordPtr[1]->size > 2) { eMaj_du = VB->TexCoordPtr[1]->data[vMax][2]*wMax - VB->TexCoordPtr[1]->data[vMin][2]*wMin; eBot_du = VB->TexCoordPtr[1]->data[vMid][2]*wMid - VB->TexCoordPtr[1]->data[vMin][2]*wMin; du1dx = oneOverArea * (eMaj_du * eBot.dy - eMaj.dy * eBot_du); du1dy = oneOverArea * (eMaj.dx * eBot_du - eMaj_du * eBot.dx); } else { du1dx = 0; du1dy = 0; } if (VB->TexCoordPtr[1]->size > 3) { eMaj_dv = VB->TexCoordPtr[1]->data[vMax][3]*wMax - VB->TexCoordPtr[1]->data[vMin][3]*wMin; eBot_dv = VB->TexCoordPtr[1]->data[vMid][3]*wMid - VB->TexCoordPtr[1]->data[vMin][3]*wMin; dv1dx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv); dv1dy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx); } else { eMaj_dv = wMax - wMin; eBot_dv = wMid - wMin; dv1dx = oneOverArea * (eMaj_dv * eBot.dy - eMaj.dy * eBot_dv); dv1dy = oneOverArea * (eMaj.dx * eBot_dv - eMaj_dv * eBot.dx); } } #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. */ { int subTriangle; GLfixed fx, fxLeftEdge, fxRightEdge, fdxLeftEdge, fdxRightEdge; GLfixed fdxOuter; int idxOuter; float dxOuter; GLfixed fError, fdError; float adjx, adjy; GLfixed fy; int iy; #ifdef PIXEL_ADDRESS PIXEL_TYPE *pRow; int dPRowOuter, dPRowInner; /* offset in bytes */ #endif #ifdef INTERP_Z # ifdef DEPTH_TYPE DEPTH_TYPE *zRow; int dZRowOuter, dZRowInner; /* offset in bytes */ # endif GLfixed fz, fdzOuter, fdzInner; #endif #ifdef INTERP_RGB GLfixed fr, fdrOuter, fdrInner; GLfixed fg, fdgOuter, fdgInner; GLfixed fb, fdbOuter, fdbInner; #endif #ifdef INTERP_SPEC GLfixed fsr, fdsrOuter, fdsrInner; GLfixed fsg, fdsgOuter, fdsgInner; GLfixed fsb, fdsbOuter, fdsbInner; #endif #ifdef INTERP_ALPHA GLfixed fa, fdaOuter, fdaInner; #endif #ifdef INTERP_INDEX GLfixed fi, fdiOuter, fdiInner; #endif #ifdef INTERP_INT_ST GLfixed fs, fdsOuter, fdsInner; GLfixed ft, fdtOuter, fdtInner; #endif #ifdef INTERP_STUV GLfloat sLeft, dsOuter, dsInner; GLfloat tLeft, dtOuter, dtInner; GLfloat uLeft, duOuter, duInner; GLfloat vLeft, dvOuter, dvInner; #endif #ifdef INTERP_STUV1 GLfloat s1Left, ds1Outer, ds1Inner; GLfloat t1Left, dt1Outer, dt1Inner; GLfloat u1Left, du1Outer, du1Inner; GLfloat v1Left, dv1Outer, dv1Inner; #endif for (subTriangle=0; subTriangle<=1; subTriangle++) { EdgeT *eLeft, *eRight; int setupLeft, setupRight; int lines; if (subTriangle==0) { /* bottom half */ if (ltor) { 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 (ltor) { 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) { GLint vLower; GLfixed fsx = eLeft->fsx; fx = FixedCeil(fsx); 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 = (float) idxOuter; (void) dxOuter; fy = eLeft->fsy; iy = FixedToInt(fy); adjx = (float)(fx - eLeft->fx0); /* SCALED! */ adjy = eLeft->adjy; /* SCALED! */ (void) adjx; /* silence compiler warnings */ (void) adjy; /* silence compiler warnings */ vLower = eLeft->v0; (void) vLower; /* silence compiler warnings */ #ifdef PIXEL_ADDRESS { pRow = (PIXEL_TYPE *)PIXEL_ADDRESS( FixedToInt(fxLeftEdge), iy ); 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, fy). 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 = VB->Win.data[vLower][2] + ctx->PolygonZoffset; if (depthBits <= 16) { /* interpolate fixed-pt values */ GLfloat tmp = (z0 * FIXED_SCALE + dzdx * adjx + dzdy * adjy) + FIXED_HALF; if (tmp < MAX_GLUINT / 2) fz = (GLfixed) tmp; else fz = MAX_GLUINT / 2; fdzOuter = SignedFloatToFixed(dzdy + dxOuter * dzdx); } else { /* interpolate depth values exactly */ fz = (GLint) (z0 + dzdx*FixedToFloat(adjx) + dzdy*FixedToFloat(adjy)); fdzOuter = (GLint) (dzdy + dxOuter * dzdx); } # ifdef DEPTH_TYPE zRow = (DEPTH_TYPE *) _mesa_zbuffer_address(ctx, FixedToInt(fxLeftEdge), iy); dZRowOuter = (ctx->DrawBuffer->Width + idxOuter) * sizeof(DEPTH_TYPE); # endif } #endif #ifdef INTERP_RGB fr = (GLfixed)(IntToFixed(VB->ColorPtr->data[vLower][0]) + drdx * adjx + drdy * adjy) + FIXED_HALF; fdrOuter = SignedFloatToFixed(drdy + dxOuter * drdx); fg = (GLfixed)(IntToFixed(VB->ColorPtr->data[vLower][1]) + dgdx * adjx + dgdy * adjy) + FIXED_HALF; fdgOuter = SignedFloatToFixed(dgdy + dxOuter * dgdx); fb = (GLfixed)(IntToFixed(VB->ColorPtr->data[vLower][2]) + dbdx * adjx + dbdy * adjy) + FIXED_HALF; fdbOuter = SignedFloatToFixed(dbdy + dxOuter * dbdx); #endif #ifdef INTERP_SPEC fsr = (GLfixed)(IntToFixed(VB->Specular[vLower][0]) + dsrdx * adjx + dsrdy * adjy) + FIXED_HALF; fdsrOuter = SignedFloatToFixed(dsrdy + dxOuter * dsrdx); fsg = (GLfixed)(IntToFixed(VB->Specular[vLower][1]) + dsgdx * adjx + dsgdy * adjy) + FIXED_HALF; fdsgOuter = SignedFloatToFixed(dsgdy + dxOuter * dsgdx); fsb = (GLfixed)(IntToFixed(VB->Specular[vLower][2]) + dsbdx * adjx + dsbdy * adjy) + FIXED_HALF; fdsbOuter = SignedFloatToFixed(dsbdy + dxOuter * dsbdx); #endif #ifdef INTERP_ALPHA fa = (GLfixed)(IntToFixed(VB->ColorPtr->data[vLower][3]) + dadx * adjx + dady * adjy) + FIXED_HALF; fdaOuter = SignedFloatToFixed(dady + dxOuter * dadx); #endif #ifdef INTERP_INDEX fi = (GLfixed)(VB->IndexPtr->data[vLower] * FIXED_SCALE + didx * adjx + didy * adjy) + FIXED_HALF; fdiOuter = SignedFloatToFixed(didy + dxOuter * didx); #endif #ifdef INTERP_INT_ST { GLfloat s0, t0; s0 = VB->TexCoordPtr[0]->data[vLower][0] * S_SCALE; fs = (GLfixed)(s0 * FIXED_SCALE + dsdx * adjx + dsdy * adjy) + FIXED_HALF; fdsOuter = SignedFloatToFixed(dsdy + dxOuter * dsdx); if (VB->TexCoordPtr[0]->size > 1) { t0 = VB->TexCoordPtr[0]->data[vLower][1] * T_SCALE; ft = (GLfixed)(t0 * FIXED_SCALE + dtdx * adjx + dtdy * adjy) + FIXED_HALF; fdtOuter = SignedFloatToFixed(dtdy + dxOuter * dtdx); } else { t0 = 0; ft = (GLfixed) FIXED_HALF; fdtOuter = SignedFloatToFixed(0); } } #endif #ifdef INTERP_STUV { GLfloat invW = VB->Win.data[vLower][3]; GLfloat s0, t0, u0, v0; s0 = VB->TexCoordPtr[0]->data[vLower][0] * invW; sLeft = s0 + (dsdx * adjx + dsdy * adjy) * (1.0F/FIXED_SCALE); dsOuter = dsdy + dxOuter * dsdx; if (VB->TexCoordPtr[0]->size > 1) { t0 = VB->TexCoordPtr[0]->data[vLower][1] * invW; tLeft = t0 + (dtdx * adjx + dtdy * adjy) * (1.0F/FIXED_SCALE); dtOuter = dtdy + dxOuter * dtdx; } else { tLeft = dtOuter = 0; } if (VB->TexCoordPtr[0]->size > 2) { u0 = VB->TexCoordPtr[0]->data[vLower][2] * invW; uLeft = u0 + (dudx * adjx + dudy * adjy) * (1.0F/FIXED_SCALE); duOuter = dudy + dxOuter * dudx; } else { uLeft = duOuter = 0; } if (VB->TexCoordPtr[0]->size > 3) { v0 = VB->TexCoordPtr[0]->data[vLower][3] * invW; } else { v0 = invW; } vLeft = v0 + (dvdx * adjx + dvdy * adjy) * (1.0F/FIXED_SCALE); dvOuter = dvdy + dxOuter * dvdx; } #endif #ifdef INTERP_STUV1 { GLfloat invW = VB->Win.data[vLower][3]; GLfloat s0, t0, u0, v0; s0 = VB->TexCoordPtr[1]->data[vLower][0] * invW; s1Left = s0 + (ds1dx * adjx + ds1dy * adjy) * (1.0F/FIXED_SCALE); ds1Outer = ds1dy + dxOuter * ds1dx; if (VB->TexCoordPtr[0]->size > 1) { t0 = VB->TexCoordPtr[1]->data[vLower][1] * invW; t1Left = t0 + (dt1dx * adjx + dt1dy * adjy) * (1.0F/FIXED_SCALE); dt1Outer = dt1dy + dxOuter * dt1dx; } else { t1Left = dt1Outer = 0; } if (VB->TexCoordPtr[0]->size > 2) { u0 = VB->TexCoordPtr[1]->data[vLower][2] * invW; u1Left = u0 + (du1dx * adjx + du1dy * adjy) * (1.0F/FIXED_SCALE); du1Outer = du1dy + dxOuter * du1dx; } else { u1Left = du1Outer = 0; } if (VB->TexCoordPtr[0]->size > 3) { v0 = VB->TexCoordPtr[1]->data[vLower][3] * invW; } else { v0 = invW; } v1Left = v0 + (dv1dx * adjx + dv1dy * adjy) * (1.0F/FIXED_SCALE); dv1Outer = dv1dy + dxOuter * dv1dx; } #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 + fdzdx; #endif #ifdef INTERP_RGB fdrInner = fdrOuter + fdrdx; fdgInner = fdgOuter + fdgdx; fdbInner = fdbOuter + fdbdx; #endif #ifdef INTERP_SPEC fdsrInner = fdsrOuter + fdsrdx; fdsgInner = fdsgOuter + fdsgdx; fdsbInner = fdsbOuter + fdsbdx; #endif #ifdef INTERP_ALPHA fdaInner = fdaOuter + fdadx; #endif #ifdef INTERP_INDEX fdiInner = fdiOuter + fdidx; #endif #ifdef INTERP_INT_ST fdsInner = fdsOuter + fdsdx; fdtInner = fdtOuter + fdtdx; #endif #ifdef INTERP_STUV dsInner = dsOuter + dsdx; dtInner = dtOuter + dtdx; duInner = duOuter + dudx; dvInner = dvOuter + dvdx; #endif #ifdef INTERP_STUV1 ds1Inner = ds1Outer + ds1dx; dt1Inner = dt1Outer + dt1dx; du1Inner = du1Outer + du1dx; dv1Inner = dv1Outer + dv1dx; #endif while (lines>0) { /* initialize the span interpolants to the leftmost value */ /* ff = fixed-pt fragment */ #ifdef INTERP_Z GLfixed ffz = fz; #endif #ifdef INTERP_RGB GLfixed ffr = fr, ffg = fg, ffb = fb; #endif #ifdef INTERP_SPEC GLfixed ffsr = fsr, ffsg = fsg, ffsb = fsb; #endif #ifdef INTERP_ALPHA GLfixed ffa = fa; #endif #ifdef INTERP_INDEX GLfixed ffi = fi; #endif #ifdef INTERP_INT_ST GLfixed ffs = fs, fft = ft; #endif #ifdef INTERP_STUV GLfloat ss = sLeft, tt = tLeft, uu = uLeft, vv = vLeft; #endif #ifdef INTERP_STUV1 GLfloat ss1 = s1Left, tt1 = t1Left, uu1 = u1Left, vv1 = v1Left; #endif GLint left = FixedToInt(fxLeftEdge); GLint right = FixedToInt(fxRightEdge); #ifdef INTERP_RGB { /* need this to accomodate round-off errors */ GLfixed ffrend = ffr+(right-left-1)*fdrdx; GLfixed ffgend = ffg+(right-left-1)*fdgdx; GLfixed ffbend = ffb+(right-left-1)*fdbdx; if (ffrend<0) ffr -= ffrend; if (ffgend<0) ffg -= ffgend; if (ffbend<0) ffb -= ffbend; if (ffr<0) ffr = 0; if (ffg<0) ffg = 0; if (ffb<0) ffb = 0; } #endif #ifdef INTERP_SPEC { /* need this to accomodate round-off errors */ GLfixed ffsrend = ffsr+(right-left-1)*fdsrdx; GLfixed ffsgend = ffsg+(right-left-1)*fdsgdx; GLfixed ffsbend = ffsb+(right-left-1)*fdsbdx; if (ffsrend<0) ffsr -= ffsrend; if (ffsgend<0) ffsg -= ffsgend; if (ffsbend<0) ffsb -= ffsbend; if (ffsr<0) ffsr = 0; if (ffsg<0) ffsg = 0; if (ffsb<0) ffsb = 0; } #endif #ifdef INTERP_ALPHA { GLfixed ffaend = ffa+(right-left-1)*fdadx; if (ffaend<0) ffa -= ffaend; if (ffa<0) ffa = 0; } #endif #ifdef INTERP_INDEX if (ffi<0) ffi = 0; #endif INNER_LOOP( left, right, iy ); /* * 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. */ iy++; 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 fz += fdzOuter; #endif #ifdef INTERP_RGB fr += fdrOuter; fg += fdgOuter; fb += fdbOuter; #endif #ifdef INTERP_SPEC fsr += fdsrOuter; fsg += fdsgOuter; fsb += fdsbOuter; #endif #ifdef INTERP_ALPHA fa += fdaOuter; #endif #ifdef INTERP_INDEX fi += fdiOuter; #endif #ifdef INTERP_INT_ST fs += fdsOuter; ft += fdtOuter; #endif #ifdef INTERP_STUV sLeft += dsOuter; tLeft += dtOuter; uLeft += duOuter; vLeft += dvOuter; #endif #ifdef INTERP_STUV1 s1Left += ds1Outer; t1Left += dt1Outer; u1Left += du1Outer; v1Left += dv1Outer; #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 fz += fdzInner; #endif #ifdef INTERP_RGB fr += fdrInner; fg += fdgInner; fb += fdbInner; #endif #ifdef INTERP_SPEC fsr += fdsrInner; fsg += fdsgInner; fsb += fdsbInner; #endif #ifdef INTERP_ALPHA fa += fdaInner; #endif #ifdef INTERP_INDEX fi += fdiInner; #endif #ifdef INTERP_INT_ST fs += fdsInner; ft += fdtInner; #endif #ifdef INTERP_STUV sLeft += dsInner; tLeft += dtInner; uLeft += duInner; vLeft += dvInner; #endif #ifdef INTERP_STUV1 s1Left += ds1Inner; t1Left += dt1Inner; u1Left += du1Inner; v1Left += dv1Inner; #endif } } /*while lines>0*/ } /* for subTriangle */ } } } #undef SETUP_CODE #undef INNER_LOOP #undef PIXEL_TYPE #undef BYTES_PER_ROW #undef PIXEL_ADDRESS #undef INTERP_Z #undef INTERP_RGB #undef INTERP_SPEC #undef INTERP_ALPHA #undef INTERP_INDEX #undef INTERP_INT_ST #undef INTERP_STUV #undef INTERP_STUV1 #undef S_SCALE #undef T_SCALE #undef FixedToDepth