/************************************************************************** * * 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. * **************************************************************************/ /* * Binning code for triangles */ #include "lp_setup.h" #include "lp_state.h" #include "util/u_math.h" #include "util/u_memory.h" /** * Compute a0 for a constant-valued coefficient (GL_FLAT shading). */ static void constant_coef( struct tgsi_interp_coef *coef, const float (*v3)[4], unsigned vert_attr, unsigned i ) { coef->a0[i] = v3[vert_attr][i]; coef->dadx[i] = 0; coef->dady[i] = 0; } /** * Compute a0, dadx and dady for a linearly interpolated coefficient, * for a triangle. */ static void linear_coef( struct triangle *tri, struct tgsi_interp_coef *coef, const float (*v1)[4], const float (*v2)[4], const float (*v3)[4], unsigned vert_attr, unsigned i) { float a1 = v1[vert_attr][i]; float a2 = v2[vert_attr][i]; float a3 = v3[vert_attr][i]; float da12 = a1 - a2; float da31 = a3 - a1; float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * tri->oneoverarea; float dady = (da31 * tri->dx12 - tri->dx31 * da12) * tri->oneoverarea; coef->dadx[i] = dadx; coef->dady[i] = dady; /* calculate a0 as the value which would be sampled for the * fragment at (0,0), taking into account that we want to sample at * pixel centers, in other words (0.5, 0.5). * * this is neat but unfortunately not a good way to do things for * triangles with very large values of dadx or dady as it will * result in the subtraction and re-addition from a0 of a very * large number, which means we'll end up loosing a lot of the * fractional bits and precision from a0. the way to fix this is * to define a0 as the sample at a pixel center somewhere near vmin * instead - i'll switch to this later. */ coef->a0[i] = (v1[vert_attr][i] - (dadx * (v1[0][0] - 0.5f) + dady * (v1[0][1] - 0.5f))); } /** * 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 perspective_coef( struct triangle *tri, struct tgsi_interp_coef *coef, const float (*v1)[4], const float (*v2)[4], const float (*v3)[4], unsigned vert_attr, unsigned i) { /* premultiply by 1/w (v[0][3] is always 1/w): */ float a1 = v1[vert_attr][i] * v1[0][3]; float a2 = v2[vert_attr][i] * v2[0][3]; float a3 = v3[vert_attr][i] * v3[0][3]; float da12 = a1 - a2; float da31 = a3 - a1; float dadx = (da12 * tri->dy31 - tri->dy12 * da31) * tri->oneoverarea; float dady = (da31 * tri->dx12 - tri->dx31 * da12) * tri->oneoverarea; coef->dadx[i] = dadx; coef->dady[i] = dady; coef->a0[i] = (a1 - (dadx * (v1[0][0] - 0.5f) + dady * (v1[0][1] - 0.5f))); } /** * Special coefficient setup for gl_FragCoord. * X and Y are trivial, though Y has to be inverted for OpenGL. * Z and W are copied from position_coef which should have already been computed. * We could do a bit less work if we'd examine gl_FragCoord's swizzle mask. */ static void setup_fragcoord_coef(struct triangle *tri, unsigned slot) { /*X*/ tri->coef[slot].a0[0] = 0.0; tri->coef[slot].dadx[0] = 1.0; tri->coef[slot].dady[0] = 0.0; /*Y*/ tri->coef[slot].a0[1] = 0.0; tri->coef[slot].dadx[1] = 0.0; tri->coef[slot].dady[1] = 1.0; /*Z*/ tri->coef[slot].a0[2] = tri->position_coef.a0[2]; tri->coef[slot].dadx[2] = tri->position_coef.dadx[2]; tri->coef[slot].dady[2] = tri->position_coef.dady[2]; /*W*/ tri->coef[slot].a0[3] = tri->position_coef.a0[3]; tri->coef[slot].dadx[3] = tri->position_coef.dadx[3]; tri->coef[slot].dady[3] = tri->position_coef.dady[3]; } /** * Compute the tri->coef[] array dadx, dady, a0 values. */ static void setup_tri_coefficients( struct setup_context *setup, struct triangle *tri, const float (*v1)[4], const float (*v2)[4], const float (*v3)[4], boolean frontface ) { const struct vertex_info *vinfo = setup->vinfo; unsigned input; /* z and w are done by linear interpolation: */ linear_coef(tri, tri->position_coef, v1, v2, v3, 0, 2); linear_coef(tri, tri->position_coef, v1, v2, v3, 0, 3); /* setup interpolation for all the remaining attributes: */ for (input = 0; input < vinfo->num_fs_inputs; input++) { unsigned vert_attr = vinfo->attrib[input].src_index; unsigned i; switch (vinfo->attrib[input].interp_mode) { case INTERP_CONSTANT: for (i = 0; i < NUM_CHANNELS; i++) constant_coef(tri->coef[input], v3, vert_attr, i); break; case INTERP_LINEAR: for (i = 0; i < NUM_CHANNELS; i++) linear_coef(tri, tri->coef[input], v1, v2, v3, vert_attr, i); break; case INTERP_PERSPECTIVE: for (i = 0; i < NUM_CHANNELS; i++) perspective_coef(tri, tri->coef[input], v1, v2, v3, vert_attr, i); break; case INTERP_POS: setup_fragcoord_coef(tri, input); break; case INTERP_FACING: tri->coef[input].a0[0] = 1.0f - frontface; tri->coef[input].dadx[0] = 0.0; tri->coef[input].dady[0] = 0.0; break; default: assert(0); } } } /* XXX: do this by add/subtracting a large floating point number: */ static inline float subpixel_snap( float a ) { int i = a * 16; return (float)i * (1.0/16); } /* to avoid having to allocate power-of-four, square render targets, * end up having a specialized version of the above that runs only at * the topmost level. * * at the topmost level there may be an arbitary number of steps on * either dimension, so this loop needs to be either separately * code-generated and unrolled for each render target size, or kept as * generic looping code: */ #define MIN3(a,b,c) MIN2(MIN2(a,b),c) #define MAX3(a,b,c) MAX2(MAX2(a,b),c) static void do_triangle_ccw(struct lp_setup *setup, const float (*v1)[4], const float (*v2)[4], const float (*v3)[4], boolean frontfacing ) { const int rt_width = setup->framebuffer.cbufs[0]->width; const int rt_height = setup->framebuffer.cbufs[0]->height; const float y1 = subpixel_snap(v1[0][1]); const float y2 = subpixel_snap(v2[0][1]); const float y3 = subpixel_snap(v3[0][1]); const float x1 = subpixel_snap(v1[0][0]); const float x2 = subpixel_snap(v2[0][0]); const float x3 = subpixel_snap(v3[0][0]); struct triangle *tri = allocate_triangle( setup ); float area; float c1, c2, c3; int i; int minx, maxx, miny, maxy; tri->dx12 = x1 - x2; tri->dx23 = x2 - x3; tri->dx31 = x3 - x1; tri->dy12 = y1 - y2; tri->dy23 = y2 - y3; tri->dy31 = y3 - y1; area = (tri->dx12 * tri->dy31 - tri->dx31 * tri->dy12); /* Cull non-ccw and zero-sized triangles. */ if (area <= 0 || util_is_inf_or_nan(area)) return; // Bounding rectangle minx = util_iround(MIN3(x1, x2, x3) - .5); maxx = util_iround(MAX3(x1, x2, x3) + .5); miny = util_iround(MIN3(y1, y2, y3) - .5); maxy = util_iround(MAX3(y1, y2, y3) + .5); /* Clamp to framebuffer (or tile) dimensions: */ miny = MAX2(0, miny); minx = MAX2(0, minx); maxy = MIN2(rt_height, maxy); maxx = MIN2(rt_width, maxx); if (miny == maxy || minx == maxx) return; /* The only divide in this code. Is it really needed? */ tri->oneoverarea = 1.0f / area; /* Setup parameter interpolants: */ setup_tri_coefficients( setup, tri, v1, v2, v3, frontfacing ); /* half-edge constants, will be interated over the whole * rendertarget. */ c1 = tri->dy12 * x1 - tri->dx12 * y1; c2 = tri->dy23 * x2 - tri->dx23 * y2; c3 = tri->dy31 * x3 - tri->dx31 * y3; /* correct for top-left fill convention: */ if (tri->dy12 < 0 || (tri->dy12 == 0 && tri->dx12 > 0)) c1++; if (tri->dy23 < 0 || (tri->dy23 == 0 && tri->dx23 > 0)) c2++; if (tri->dy31 < 0 || (tri->dy31 == 0 && tri->dx31 > 0)) c3++; /* find trivial reject offsets for each edge for a single-pixel * sized block. These will be scaled up at each recursive level to * match the active blocksize. Scaling in this way works best if * the blocks are square. */ tri->eo1 = 0; if (tri->dy12 < 0) tri->eo1 -= tri->dy12; if (tri->dx12 > 0) tri->eo1 += tri->dx12; tri->eo2 = 0; if (tri->dy23 < 0) tri->eo2 -= tri->dy23; if (tri->dx23 > 0) tri->eo2 += tri->dx23; tri->eo3 = 0; if (tri->dy31 < 0) tri->eo3 -= tri->dy31; if (tri->dx31 > 0) tri->eo3 += tri->dx31; /* Calculate trivial accept offsets from the above. */ tri->ei1 = tri->dx12 - tri->dy12 - tri->eo1; tri->ei2 = tri->dx23 - tri->dy23 - tri->eo2; tri->ei3 = tri->dx31 - tri->dy31 - tri->eo3; minx &= ~(TILESIZE-1); /* aligned blocks */ miny &= ~(TILESIZE-1); /* aligned blocks */ c1 += tri->dx12 * miny - tri->dy12 * minx; c2 += tri->dx23 * miny - tri->dy23 * minx; c3 += tri->dx31 * miny - tri->dy31 * minx; /* Convert to tile coordinates: */ minx /= TILESIZE; maxx /= TILESIZE; miny /= TILESIZE; maxy /= TILESIZE; if (miny == maxy && minx == maxx) { /* Triangle is contained in a single tile: */ bin_command(setup->tile[minx][miny], lp_rast_triangle, tri ); } else { const int step = TILESIZE; float ei1 = tri->ei1 * step; float ei2 = tri->ei2 * step; float ei3 = tri->ei3 * step; float eo1 = tri->eo1 * step; float eo2 = tri->eo2 * step; float eo3 = tri->eo3 * step; float xstep1 = -step * tri->dy12; float xstep2 = -step * tri->dy23; float xstep3 = -step * tri->dy31; float ystep1 = step * tri->dx12; float ystep2 = step * tri->dx23; float ystep3 = step * tri->dx31; int x, y; /* Subdivide space into NxM blocks, where each block is square and * power-of-four in dimension. * * Trivially accept or reject blocks, else jump to per-pixel * examination above. */ for (y = miny; y < maxy; y++) { float cx1 = c1; float cx2 = c2; float cx3 = c3; for (x = minx; x < maxx; x++) { if (cx1 + eo1 < 0 || cx2 + eo2 < 0 || cx3 + eo3 < 0) { /* do nothing */ } else if (cx1 + ei1 > 0 && cx2 + ei2 > 0 && cx3 + ei3 > 0) { /* shade whole tile */ bin_command(setup->tile[x][y], lp_rast_shade_tile, &tri->inputs ); } else { /* shade partial tile */ bin_command(setup->tile[x][y], lp_rast_triangle, tri ); } /* Iterate cx values across the region: */ cx1 += xstep1; cx2 += xstep2; cx3 += xstep3; } /* Iterate c values down the region: */ c1 += ystep1; c2 += ystep2; c3 += ystep3; } } } static void triangle_cw( struct setup_context *setup, const float (*v0)[4], const float (*v1)[4], const float (*v2)[4] ) { do_triangle_ccw( setup, v1, v0, v2, !setup->ccw_is_frontface ); } static void triangle_ccw( struct setup_context *setup, const float (*v0)[4], const float (*v1)[4], const float (*v2)[4] ) { do_triangle_ccw( setup, v0, v1, v2, setup->ccw_is_frontface ); } static void triangle_both( struct setup_context *setup, const float (*v0)[4], const float (*v1)[4], const float (*v2)[4] ) { /* edge vectors e = v0 - v2, f = v1 - v2 */ const float ex = v0[0][0] - v2[0][0]; const float ey = v0[0][1] - v2[0][1]; const float fx = v1[0][0] - v2[0][0]; const float fy = v1[0][1] - v2[0][1]; /* det = cross(e,f).z */ if (ex * fy - ey * fx < 0) triangle_ccw( setup, v0, v1, v2 ); else triangle_cw( setup, v0, v1, v2 ); } static void triangle_nop( struct setup_context *setup, const float (*v0)[4], const float (*v1)[4], const float (*v2)[4] ) { } void setup_set_tri_state( struct setup_context *setup, unsigned cull_mode, boolean ccw_is_frontface) { setup->ccw_is_frontface = ccw_is_frontface; switch (cull_mode) { case PIPE_WINDING_NONE: setup->triangle = triangle_both; break; case PIPE_WINDING_CCW: setup->triangle = triangle_cw; break; case PIPE_WINDING_CW: setup->triangle = triangle_ccw; break; default: setup->triangle = triangle_nop; break; } }