/************************************************************************** * * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas. * 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, sub license, 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 (including the * next paragraph) 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 NON-INFRINGEMENT. * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS 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 rendering within a tile. */ #include #include "pipe/p_compiler.h" #include "pipe/p_format.h" #include "util/u_math.h" #include "spu_colorpack.h" #include "spu_main.h" #include "spu_texture.h" #include "spu_tile.h" #include "spu_tri.h" /** Masks are uint[4] vectors with each element being 0 or 0xffffffff */ typedef vector unsigned int mask_t; /** * Simplified types taken from other parts of Gallium */ struct vertex_header { vector float data[1]; }; /* XXX fix this */ #undef CEILF #define CEILF(X) ((float) (int) ((X) + 0.99999)) #define QUAD_TOP_LEFT 0 #define QUAD_TOP_RIGHT 1 #define QUAD_BOTTOM_LEFT 2 #define QUAD_BOTTOM_RIGHT 3 #define MASK_TOP_LEFT (1 << QUAD_TOP_LEFT) #define MASK_TOP_RIGHT (1 << QUAD_TOP_RIGHT) #define MASK_BOTTOM_LEFT (1 << QUAD_BOTTOM_LEFT) #define MASK_BOTTOM_RIGHT (1 << QUAD_BOTTOM_RIGHT) #define MASK_ALL 0xf #define DEBUG_VERTS 0 /** * Triangle edge info */ struct edge { float dx; /**< X(v1) - X(v0), used only during setup */ float dy; /**< Y(v1) - Y(v0), used only during setup */ float dxdy; /**< dx/dy */ float sx, sy; /**< first sample point coord */ int lines; /**< number of lines on this edge */ }; struct interp_coef { vector float a0; vector float dadx; vector float dady; }; /** * Triangle setup info (derived from draw_stage). * Also used for line drawing (taking some liberties). */ struct setup_stage { /* Vertices are just an array of floats making up each attribute in * turn. Currently fixed at 4 floats, but should change in time. * Codegen will help cope with this. */ const struct vertex_header *vmax; const struct vertex_header *vmid; const struct vertex_header *vmin; const struct vertex_header *vprovoke; struct edge ebot; struct edge etop; struct edge emaj; float oneOverArea; /* XXX maybe make into vector? */ uint facing; uint tx, ty; /**< position of current tile (x, y) */ int cliprect_minx, cliprect_maxx, cliprect_miny, cliprect_maxy; struct interp_coef coef[PIPE_MAX_SHADER_INPUTS]; struct { int left[2]; /**< [0] = row0, [1] = row1 */ int right[2]; int y; unsigned y_flags; unsigned mask; /**< mask of MASK_BOTTOM/TOP_LEFT/RIGHT bits */ } span; }; static struct setup_stage setup; /** * Evaluate attribute coefficients (plane equations) to compute * attribute values for the four fragments in a quad. * Eg: four colors will be computed (in AoS format). */ static INLINE void eval_coeff(uint slot, float x, float y, vector float w, vector float result[4]) { switch (spu.vertex_info.attrib[slot].interp_mode) { case INTERP_CONSTANT: result[QUAD_TOP_LEFT] = result[QUAD_TOP_RIGHT] = result[QUAD_BOTTOM_LEFT] = result[QUAD_BOTTOM_RIGHT] = setup.coef[slot].a0; break; case INTERP_LINEAR: { vector float dadx = setup.coef[slot].dadx; vector float dady = setup.coef[slot].dady; vector float topLeft = spu_add(setup.coef[slot].a0, spu_add(spu_mul(spu_splats(x), dadx), spu_mul(spu_splats(y), dady))); result[QUAD_TOP_LEFT] = topLeft; result[QUAD_TOP_RIGHT] = spu_add(topLeft, dadx); result[QUAD_BOTTOM_LEFT] = spu_add(topLeft, dady); result[QUAD_BOTTOM_RIGHT] = spu_add(spu_add(topLeft, dadx), dady); } break; case INTERP_PERSPECTIVE: { vector float dadx = setup.coef[slot].dadx; vector float dady = setup.coef[slot].dady; vector float topLeft = spu_add(setup.coef[slot].a0, spu_add(spu_mul(spu_splats(x), dadx), spu_mul(spu_splats(y), dady))); vector float wInv = spu_re(w); /* 1.0 / w */ result[QUAD_TOP_LEFT] = spu_mul(topLeft, wInv); result[QUAD_TOP_RIGHT] = spu_mul(spu_add(topLeft, dadx), wInv); result[QUAD_BOTTOM_LEFT] = spu_mul(spu_add(topLeft, dady), wInv); result[QUAD_BOTTOM_RIGHT] = spu_mul(spu_add(spu_add(topLeft, dadx), dady), wInv); } break; case INTERP_POS: case INTERP_NONE: break; default: ASSERT(0); } } /** * As above, but return 4 vectors in SOA format. * XXX this will all be re-written someday. */ static INLINE void eval_coeff_soa(uint slot, float x, float y, vector float w, vector float result[4]) { eval_coeff(slot, x, y, w, result); _transpose_matrix4x4(result, result); } /** Evalute coefficients to get Z for four pixels in a quad */ static INLINE vector float eval_z(float x, float y) { const uint slot = 0; const float dzdx = spu_extract(setup.coef[slot].dadx, 2); const float dzdy = spu_extract(setup.coef[slot].dady, 2); const float topLeft = spu_extract(setup.coef[slot].a0, 2) + x * dzdx + y * dzdy; const vector float topLeftv = spu_splats(topLeft); const vector float derivs = (vector float) { 0.0, dzdx, dzdy, dzdx + dzdy }; return spu_add(topLeftv, derivs); } /** Evalute coefficients to get W for four pixels in a quad */ static INLINE vector float eval_w(float x, float y) { const uint slot = 0; const float dwdx = spu_extract(setup.coef[slot].dadx, 3); const float dwdy = spu_extract(setup.coef[slot].dady, 3); const float topLeft = spu_extract(setup.coef[slot].a0, 3) + x * dwdx + y * dwdy; const vector float topLeftv = spu_splats(topLeft); const vector float derivs = (vector float) { 0.0, dwdx, dwdy, dwdx + dwdy }; return spu_add(topLeftv, derivs); } /** * Emit a quad (pass to next stage). No clipping is done. * Note: about 1/5 to 1/7 of the time, mask is zero and this function * should be skipped. But adding the test for that slows things down * overall. */ static INLINE void emit_quad( int x, int y, mask_t mask) { /* If any bits in mask are set... */ if (spu_extract(spu_orx(mask), 0)) { const int ix = x - setup.cliprect_minx; const int iy = y - setup.cliprect_miny; spu.cur_ctile_status = TILE_STATUS_DIRTY; spu.cur_ztile_status = TILE_STATUS_DIRTY; { /* * Run fragment shader, execute per-fragment ops, update fb/tile. */ vector float inputs[4*4], outputs[2*4]; vector float fragZ = eval_z((float) x, (float) y); vector float fragW = eval_w((float) x, (float) y); vector unsigned int kill_mask; /* setup inputs */ #if 0 eval_coeff_soa(1, (float) x, (float) y, fragW, inputs); #else uint i; for (i = 0; i < spu.vertex_info.num_attribs; i++) { eval_coeff_soa(i+1, (float) x, (float) y, fragW, inputs + i * 4); } #endif ASSERT(spu.fragment_program); ASSERT(spu.fragment_ops); /* Execute the current fragment program */ kill_mask = spu.fragment_program(inputs, outputs, spu.constants); mask = spu_andc(mask, kill_mask); /* Execute per-fragment/quad operations, including: * alpha test, z test, stencil test, blend and framebuffer writing. * Note that there are two different fragment operations functions * that can be called, one for front-facing fragments, and one * for back-facing fragments. (Often the two are the same; * but in some cases, like two-sided stenciling, they can be * very different.) So choose the correct function depending * on the calculated facing. */ spu.fragment_ops[setup.facing](ix, iy, &spu.ctile, &spu.ztile, fragZ, outputs[0*4+0], outputs[0*4+1], outputs[0*4+2], outputs[0*4+3], mask); } } } /** * Given an X or Y coordinate, return the block/quad coordinate that it * belongs to. */ static INLINE int block(int x) { return x & ~1; } /** * Compute mask which indicates which pixels in the 2x2 quad are actually inside * the triangle's bounds. * The mask is a uint4 vector and each element will be 0 or 0xffffffff. */ static INLINE mask_t calculate_mask(int x) { /* This is a little tricky. * Use & instead of && to avoid branches. * Use negation to convert true/false to ~0/0 values. */ mask_t mask; mask = spu_insert(-((x >= setup.span.left[0]) & (x < setup.span.right[0])), mask, 0); mask = spu_insert(-((x+1 >= setup.span.left[0]) & (x+1 < setup.span.right[0])), mask, 1); mask = spu_insert(-((x >= setup.span.left[1]) & (x < setup.span.right[1])), mask, 2); mask = spu_insert(-((x+1 >= setup.span.left[1]) & (x+1 < setup.span.right[1])), mask, 3); return mask; } /** * Render a horizontal span of quads */ static void flush_spans(void) { int minleft, maxright; int x; switch (setup.span.y_flags) { case 0x3: /* both odd and even lines written (both quad rows) */ minleft = MIN2(setup.span.left[0], setup.span.left[1]); maxright = MAX2(setup.span.right[0], setup.span.right[1]); break; case 0x1: /* only even line written (quad top row) */ minleft = setup.span.left[0]; maxright = setup.span.right[0]; break; case 0x2: /* only odd line written (quad bottom row) */ minleft = setup.span.left[1]; maxright = setup.span.right[1]; break; default: return; } /* OK, we're very likely to need the tile data now. * clear or finish waiting if needed. */ if (spu.cur_ctile_status == TILE_STATUS_GETTING) { /* wait for mfc_get() to complete */ //printf("SPU: %u: waiting for ctile\n", spu.init.id); wait_on_mask(1 << TAG_READ_TILE_COLOR); spu.cur_ctile_status = TILE_STATUS_CLEAN; } else if (spu.cur_ctile_status == TILE_STATUS_CLEAR) { //printf("SPU %u: clearing C tile %u, %u\n", spu.init.id, setup.tx, setup.ty); clear_c_tile(&spu.ctile); spu.cur_ctile_status = TILE_STATUS_DIRTY; } ASSERT(spu.cur_ctile_status != TILE_STATUS_DEFINED); if (spu.read_depth_stencil) { if (spu.cur_ztile_status == TILE_STATUS_GETTING) { /* wait for mfc_get() to complete */ //printf("SPU: %u: waiting for ztile\n", spu.init.id); wait_on_mask(1 << TAG_READ_TILE_Z); spu.cur_ztile_status = TILE_STATUS_CLEAN; } else if (spu.cur_ztile_status == TILE_STATUS_CLEAR) { //printf("SPU %u: clearing Z tile %u, %u\n", spu.init.id, setup.tx, setup.ty); clear_z_tile(&spu.ztile); spu.cur_ztile_status = TILE_STATUS_DIRTY; } ASSERT(spu.cur_ztile_status != TILE_STATUS_DEFINED); } /* XXX this loop could be moved into the above switch cases and * calculate_mask() could be simplified a bit... */ for (x = block(minleft); x <= block(maxright); x += 2) { emit_quad( x, setup.span.y, calculate_mask( x )); } setup.span.y = 0; setup.span.y_flags = 0; setup.span.right[0] = 0; setup.span.right[1] = 0; } #if DEBUG_VERTS static void print_vertex(const struct vertex_header *v) { uint i; fprintf(stderr, " Vertex: (%p)\n", v); for (i = 0; i < spu.vertex_info.num_attribs; i++) { fprintf(stderr, " %d: %f %f %f %f\n", i, spu_extract(v->data[i], 0), spu_extract(v->data[i], 1), spu_extract(v->data[i], 2), spu_extract(v->data[i], 3)); } } #endif /** * Sort vertices from top to bottom. * Compute area and determine front vs. back facing. * Do coarse clip test against tile bounds * \return FALSE if tri is totally outside tile, TRUE otherwise */ static boolean setup_sort_vertices(const struct vertex_header *v0, const struct vertex_header *v1, const struct vertex_header *v2) { float area, sign; #if DEBUG_VERTS if (spu.init.id==0) { fprintf(stderr, "SPU %u: Triangle:\n", spu.init.id); print_vertex(v0); print_vertex(v1); print_vertex(v2); } #endif /* determine bottom to top order of vertices */ { float y0 = spu_extract(v0->data[0], 1); float y1 = spu_extract(v1->data[0], 1); float y2 = spu_extract(v2->data[0], 1); if (y0 <= y1) { if (y1 <= y2) { /* y0<=y1<=y2 */ setup.vmin = v0; setup.vmid = v1; setup.vmax = v2; sign = -1.0f; } else if (y2 <= y0) { /* y2<=y0<=y1 */ setup.vmin = v2; setup.vmid = v0; setup.vmax = v1; sign = -1.0f; } else { /* y0<=y2<=y1 */ setup.vmin = v0; setup.vmid = v2; setup.vmax = v1; sign = 1.0f; } } else { if (y0 <= y2) { /* y1<=y0<=y2 */ setup.vmin = v1; setup.vmid = v0; setup.vmax = v2; sign = 1.0f; } else if (y2 <= y1) { /* y2<=y1<=y0 */ setup.vmin = v2; setup.vmid = v1; setup.vmax = v0; sign = 1.0f; } else { /* y1<=y2<=y0 */ setup.vmin = v1; setup.vmid = v2; setup.vmax = v0; sign = -1.0f; } } } /* Check if triangle is completely outside the tile bounds */ if (spu_extract(setup.vmin->data[0], 1) > setup.cliprect_maxy) return FALSE; if (spu_extract(setup.vmax->data[0], 1) < setup.cliprect_miny) return FALSE; if (spu_extract(setup.vmin->data[0], 0) < setup.cliprect_minx && spu_extract(setup.vmid->data[0], 0) < setup.cliprect_minx && spu_extract(setup.vmax->data[0], 0) < setup.cliprect_minx) return FALSE; if (spu_extract(setup.vmin->data[0], 0) > setup.cliprect_maxx && spu_extract(setup.vmid->data[0], 0) > setup.cliprect_maxx && spu_extract(setup.vmax->data[0], 0) > setup.cliprect_maxx) return FALSE; setup.ebot.dx = spu_extract(setup.vmid->data[0], 0) - spu_extract(setup.vmin->data[0], 0); setup.ebot.dy = spu_extract(setup.vmid->data[0], 1) - spu_extract(setup.vmin->data[0], 1); setup.emaj.dx = spu_extract(setup.vmax->data[0], 0) - spu_extract(setup.vmin->data[0], 0); setup.emaj.dy = spu_extract(setup.vmax->data[0], 1) - spu_extract(setup.vmin->data[0], 1); setup.etop.dx = spu_extract(setup.vmax->data[0], 0) - spu_extract(setup.vmid->data[0], 0); setup.etop.dy = spu_extract(setup.vmax->data[0], 1) - spu_extract(setup.vmid->data[0], 1); /* * Compute triangle's area. Use 1/area to compute partial * derivatives of attributes later. */ area = setup.emaj.dx * setup.ebot.dy - setup.ebot.dx * setup.emaj.dy; setup.oneOverArea = 1.0f / area; /* The product of area * sign indicates front/back orientation (0/1). * Just in case someone gets the bright idea of switching the front * and back constants without noticing that we're assuming their * values in this operation, also assert that the values are * what we think they are. */ ASSERT(CELL_FACING_FRONT == 0); ASSERT(CELL_FACING_BACK == 1); setup.facing = (area * sign > 0.0f) ^ (spu.rasterizer.front_winding == PIPE_WINDING_CW); setup.vprovoke = v2; return TRUE; } /** * Compute a0 for a constant-valued coefficient (GL_FLAT shading). * The value value comes from vertex->data[slot]. * The result will be put into setup.coef[slot].a0. * \param slot which attribute slot */ static INLINE void const_coeff4(uint slot) { setup.coef[slot].dadx = (vector float) {0.0, 0.0, 0.0, 0.0}; setup.coef[slot].dady = (vector float) {0.0, 0.0, 0.0, 0.0}; setup.coef[slot].a0 = setup.vprovoke->data[slot]; } /** * As above, but interp setup all four vector components. */ static INLINE void tri_linear_coeff4(uint slot) { const vector float vmin_d = setup.vmin->data[slot]; const vector float vmid_d = setup.vmid->data[slot]; const vector float vmax_d = setup.vmax->data[slot]; const vector float xxxx = spu_splats(spu_extract(setup.vmin->data[0], 0) - 0.5f); const vector float yyyy = spu_splats(spu_extract(setup.vmin->data[0], 1) - 0.5f); vector float botda = vmid_d - vmin_d; vector float majda = vmax_d - vmin_d; vector float a = spu_sub(spu_mul(spu_splats(setup.ebot.dy), majda), spu_mul(botda, spu_splats(setup.emaj.dy))); vector float b = spu_sub(spu_mul(spu_splats(setup.emaj.dx), botda), spu_mul(majda, spu_splats(setup.ebot.dx))); setup.coef[slot].dadx = spu_mul(a, spu_splats(setup.oneOverArea)); setup.coef[slot].dady = spu_mul(b, spu_splats(setup.oneOverArea)); vector float tempx = spu_mul(setup.coef[slot].dadx, xxxx); vector float tempy = spu_mul(setup.coef[slot].dady, yyyy); setup.coef[slot].a0 = spu_sub(vmin_d, spu_add(tempx, tempy)); } /** * Compute a0, dadx and dady for a perspective-corrected interpolant, * for a triangle. * We basically multiply the vertex value by 1/w before computing * the plane coefficients (a0, dadx, dady). * Later, when we compute the value at a particular fragment position we'll * divide the interpolated value by the interpolated W at that fragment. */ static void tri_persp_coeff4(uint slot) { const vector float xxxx = spu_splats(spu_extract(setup.vmin->data[0], 0) - 0.5f); const vector float yyyy = spu_splats(spu_extract(setup.vmin->data[0], 1) - 0.5f); const vector float vmin_w = spu_splats(spu_extract(setup.vmin->data[0], 3)); const vector float vmid_w = spu_splats(spu_extract(setup.vmid->data[0], 3)); const vector float vmax_w = spu_splats(spu_extract(setup.vmax->data[0], 3)); vector float vmin_d = setup.vmin->data[slot]; vector float vmid_d = setup.vmid->data[slot]; vector float vmax_d = setup.vmax->data[slot]; vmin_d = spu_mul(vmin_d, vmin_w); vmid_d = spu_mul(vmid_d, vmid_w); vmax_d = spu_mul(vmax_d, vmax_w); vector float botda = vmid_d - vmin_d; vector float majda = vmax_d - vmin_d; vector float a = spu_sub(spu_mul(spu_splats(setup.ebot.dy), majda), spu_mul(botda, spu_splats(setup.emaj.dy))); vector float b = spu_sub(spu_mul(spu_splats(setup.emaj.dx), botda), spu_mul(majda, spu_splats(setup.ebot.dx))); setup.coef[slot].dadx = spu_mul(a, spu_splats(setup.oneOverArea)); setup.coef[slot].dady = spu_mul(b, spu_splats(setup.oneOverArea)); vector float tempx = spu_mul(setup.coef[slot].dadx, xxxx); vector float tempy = spu_mul(setup.coef[slot].dady, yyyy); setup.coef[slot].a0 = spu_sub(vmin_d, spu_add(tempx, tempy)); } /** * Compute the setup.coef[] array dadx, dady, a0 values. * Must be called after setup.vmin,vmid,vmax,vprovoke are initialized. */ static void setup_tri_coefficients(void) { uint i; for (i = 0; i < spu.vertex_info.num_attribs; i++) { switch (spu.vertex_info.attrib[i].interp_mode) { case INTERP_NONE: break; case INTERP_CONSTANT: const_coeff4(i); break; case INTERP_POS: /* fall-through */ case INTERP_LINEAR: tri_linear_coeff4(i); break; case INTERP_PERSPECTIVE: tri_persp_coeff4(i); break; default: ASSERT(0); } } } static void setup_tri_edges(void) { float vmin_x = spu_extract(setup.vmin->data[0], 0) + 0.5f; float vmid_x = spu_extract(setup.vmid->data[0], 0) + 0.5f; float vmin_y = spu_extract(setup.vmin->data[0], 1) - 0.5f; float vmid_y = spu_extract(setup.vmid->data[0], 1) - 0.5f; float vmax_y = spu_extract(setup.vmax->data[0], 1) - 0.5f; setup.emaj.sy = CEILF(vmin_y); setup.emaj.lines = (int) CEILF(vmax_y - setup.emaj.sy); setup.emaj.dxdy = setup.emaj.dx / setup.emaj.dy; setup.emaj.sx = vmin_x + (setup.emaj.sy - vmin_y) * setup.emaj.dxdy; setup.etop.sy = CEILF(vmid_y); setup.etop.lines = (int) CEILF(vmax_y - setup.etop.sy); setup.etop.dxdy = setup.etop.dx / setup.etop.dy; setup.etop.sx = vmid_x + (setup.etop.sy - vmid_y) * setup.etop.dxdy; setup.ebot.sy = CEILF(vmin_y); setup.ebot.lines = (int) CEILF(vmid_y - setup.ebot.sy); setup.ebot.dxdy = setup.ebot.dx / setup.ebot.dy; setup.ebot.sx = vmin_x + (setup.ebot.sy - vmin_y) * setup.ebot.dxdy; } /** * Render the upper or lower half of a triangle. * Scissoring/cliprect is applied here too. */ static void subtriangle(struct edge *eleft, struct edge *eright, unsigned lines) { const int minx = setup.cliprect_minx; const int maxx = setup.cliprect_maxx; const int miny = setup.cliprect_miny; const int maxy = setup.cliprect_maxy; int y, start_y, finish_y; int sy = (int)eleft->sy; ASSERT((int)eleft->sy == (int) eright->sy); /* clip top/bottom */ start_y = sy; finish_y = sy + lines; if (start_y < miny) start_y = miny; if (finish_y > maxy) finish_y = maxy; start_y -= sy; finish_y -= sy; /* _mesa_printf("%s %d %d\n", __FUNCTION__, start_y, finish_y); */ for (y = start_y; y < finish_y; y++) { /* avoid accumulating adds as floats don't have the precision to * accurately iterate large triangle edges that way. luckily we * can just multiply these days. * * this is all drowned out by the attribute interpolation anyway. */ int left = (int)(eleft->sx + y * eleft->dxdy); int right = (int)(eright->sx + y * eright->dxdy); /* clip left/right */ if (left < minx) left = minx; if (right > maxx) right = maxx; if (left < right) { int _y = sy + y; if (block(_y) != setup.span.y) { flush_spans(); setup.span.y = block(_y); } setup.span.left[_y&1] = left; setup.span.right[_y&1] = right; setup.span.y_flags |= 1<<(_y&1); } } /* save the values so that emaj can be restarted: */ eleft->sx += lines * eleft->dxdy; eright->sx += lines * eright->dxdy; eleft->sy += lines; eright->sy += lines; } /** * Draw triangle into tile at (tx, ty) (tile coords) * The tile data should have already been fetched. */ boolean tri_draw(const float *v0, const float *v1, const float *v2, uint tx, uint ty) { setup.tx = tx; setup.ty = ty; /* set clipping bounds to tile bounds */ setup.cliprect_minx = tx * TILE_SIZE; setup.cliprect_miny = ty * TILE_SIZE; setup.cliprect_maxx = (tx + 1) * TILE_SIZE; setup.cliprect_maxy = (ty + 1) * TILE_SIZE; if (!setup_sort_vertices((struct vertex_header *) v0, (struct vertex_header *) v1, (struct vertex_header *) v2)) { return FALSE; /* totally clipped */ } setup_tri_coefficients(); setup_tri_edges(); setup.span.y = 0; setup.span.y_flags = 0; setup.span.right[0] = 0; setup.span.right[1] = 0; if (setup.oneOverArea < 0.0) { /* emaj on left */ subtriangle( &setup.emaj, &setup.ebot, setup.ebot.lines ); subtriangle( &setup.emaj, &setup.etop, setup.etop.lines ); } else { /* emaj on right */ subtriangle( &setup.ebot, &setup.emaj, setup.ebot.lines ); subtriangle( &setup.etop, &setup.emaj, setup.etop.lines ); } flush_spans(); return TRUE; }