diff options
author | Campbell Barton <ideasman42@gmail.com> | 2016-10-26 12:26:32 +0300 |
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committer | Campbell Barton <ideasman42@gmail.com> | 2016-10-26 15:24:58 +0300 |
commit | 44522a5b98f908928e93ab32c9d6046de4342d9b (patch) | |
tree | 648cce798671cfced20d10276b11cb4d44d5385c /source/blender/blenlib/intern/bitmap_draw_2d.c | |
parent | 8125271ddb29f8e42d00ee7667c24412d67fb2f5 (diff) |
BLI_bitmap_draw_2d: optimize polygon filling
Existing method was fine for basic polygons but didn't scale well
because its was checking all coordinates for every y-pixel.
Heres an optimized version.
Basic logic remains the same this just maintains an ordered list of intersections,
tracking in-out points, to avoid re-computing every row,
this means sorting is only done once when out of order segments are found,
the segments only need to be re-ordered if they cross each other.
Speedup isn't linear, test with full-screen complex lasso gave 11x speedup.
Diffstat (limited to 'source/blender/blenlib/intern/bitmap_draw_2d.c')
-rw-r--r-- | source/blender/blenlib/intern/bitmap_draw_2d.c | 222 |
1 files changed, 186 insertions, 36 deletions
diff --git a/source/blender/blenlib/intern/bitmap_draw_2d.c b/source/blender/blenlib/intern/bitmap_draw_2d.c index 11072f668c8..afc54511d13 100644 --- a/source/blender/blenlib/intern/bitmap_draw_2d.c +++ b/source/blender/blenlib/intern/bitmap_draw_2d.c @@ -29,14 +29,21 @@ * Utility functions for primitive drawing operations. */ +#include <limits.h> + #include "MEM_guardedalloc.h" #include "BLI_bitmap_draw_2d.h" +#include "BLI_math_base.h" +#include "BLI_sort.h" #include "BLI_utildefines.h" #include "BLI_strict_flags.h" +/* -------------------------------------------------------------------- */ +/* Draw Line */ + /** * Plot a line from \a p1 to \a p2 (inclusive). */ @@ -107,7 +114,51 @@ void BLI_bitmap_draw_2d_line_v2v2i( } } + +/* -------------------------------------------------------------------- */ +/* Draw Filled Polygon */ + +/* sort edge-segments on y, then x axis */ +static int draw_poly_v2i_n__span_y_sort(const void *a_p, const void *b_p, void *verts_p) +{ + const int (*verts)[2] = verts_p; + const int *a = a_p; + const int *b = b_p; + const int *co_a = verts[a[0]]; + const int *co_b = verts[b[0]]; + + if (co_a[1] < co_b[1]) { + return -1; + } + else if (co_a[1] > co_b[1]) { + return 1; + } + else if (co_a[0] < co_b[0]) { + return -1; + } + else if (co_a[0] > co_b[0]) { + return 1; + } + else { + /* co_a & co_b are identical, use the line closest to the x-min */ + const int *co = co_a; + co_a = verts[a[1]]; + co_b = verts[b[1]]; + int ord = (((co_b[0] - co[0]) * (co_a[1] - co[1])) - + ((co_a[0] - co[0]) * (co_b[1] - co[1]))); + if (ord > 0) { + return -1; + } + if (ord < 0) { + return 1; + } + } + return 0; +} + /** + * Draws a filled polyon with support for self intersections. + * * \param callback: Takes the x, y coords and x-span (\a x_end is not inclusive), * note that \a x_end will always be greater than \a x, so we can use: * @@ -123,59 +174,158 @@ void BLI_bitmap_draw_2d_poly_v2i_n( void (*callback)(int x, int x_end, int y, void *), void *userData) { /* Originally by Darel Rex Finley, 2007. - */ + * Optimized by Campbell Barton, 2016 to track sorted intersections. */ - int nodes, pixel_y, i, j, swap; - int *node_x = MEM_mallocN(sizeof(*node_x) * (size_t)(nr + 1), __func__); + int (*span_y)[2] = MEM_mallocN(sizeof(*span_y) * (size_t)nr, __func__); + int span_y_len = 0; - /* Loop through the rows of the image. */ - for (pixel_y = ymin; pixel_y < ymax; pixel_y++) { + for (int i_curr = 0, i_prev = nr - 1; i_curr < nr; i_prev = i_curr++) { + const int *co_prev = verts[i_prev]; + const int *co_curr = verts[i_curr]; - /* Build a list of nodes. */ - nodes = 0; j = nr - 1; - for (i = 0; i < nr; i++) { - if ((verts[i][1] < pixel_y && verts[j][1] >= pixel_y) || - (verts[j][1] < pixel_y && verts[i][1] >= pixel_y)) + if (co_prev[1] != co_curr[1]) { + /* Any segments entirely above or below the area of interest can be skipped. */ + if ((min_ii(co_prev[1], co_curr[1]) >= ymax) || + (max_ii(co_prev[1], co_curr[1]) < ymin)) { - node_x[nodes++] = (int)(verts[i][0] + - ((double)(pixel_y - verts[i][1]) / (verts[j][1] - verts[i][1])) * - (verts[j][0] - verts[i][0])); + continue; } - j = i; - } - /* Sort the nodes, via a simple "Bubble" sort. */ - i = 0; - while (i < nodes - 1) { - if (node_x[i] > node_x[i + 1]) { - SWAP_TVAL(swap, node_x[i], node_x[i + 1]); - if (i) i--; + int *s = span_y[span_y_len++]; + if (co_prev[1] < co_curr[1]) { + s[0] = i_prev; + s[1] = i_curr; } else { - i++; + s[0] = i_curr; + s[1] = i_prev; + } + } + } + + BLI_qsort_r(span_y, (size_t)span_y_len, sizeof(*span_y), draw_poly_v2i_n__span_y_sort, (void *)verts); + + struct NodeX { + int span_y_index; + int x; + } *node_x = MEM_mallocN(sizeof(*node_x) * (size_t)(nr + 1), __func__); + int node_x_len = 0; + + int span_y_index = 0; + if (span_y_len != 0 && verts[span_y[0][0]][1] < ymin) { + while ((span_y_index < span_y_len) && + (verts[span_y[span_y_index][0]][1] < ymin)) + { + BLI_assert(verts[span_y[span_y_index][0]][1] < + verts[span_y[span_y_index][1]][1]); + if (verts[span_y[span_y_index][1]][1] >= ymin) { + struct NodeX *n = &node_x[node_x_len++]; + n->span_y_index = span_y_index; + } + span_y_index += 1; + } + } + + /* Loop through the rows of the image. */ + for (int pixel_y = ymin; pixel_y < ymax; pixel_y++) { + bool is_sorted = true; + bool do_remove = false; + + for (int i = 0, x_ix_prev = INT_MIN; i < node_x_len; i++) { + struct NodeX *n = &node_x[i]; + const int *s = span_y[n->span_y_index]; + const int *co_prev = verts[s[0]]; + const int *co_curr = verts[s[1]]; + + BLI_assert(co_prev[1] < pixel_y && co_curr[1] >= pixel_y); + + const double x = (co_prev[0] - co_curr[0]); + const double y = (co_prev[1] - co_curr[1]); + const double y_px = (pixel_y - co_curr[1]); + const int x_ix = (int)((double)co_curr[0] + ((y_px / y) * x)); + n->x = x_ix; + + if (is_sorted && (x_ix_prev > x_ix)) { + is_sorted = false; + } + if (do_remove == false && co_curr[1] == pixel_y) { + do_remove = true; + } + x_ix_prev = x_ix; + } + + /* Sort the nodes, via a simple "Bubble" sort. */ + if (is_sorted == false) { + int i = 0; + const int node_x_end = node_x_len - 1; + while (i < node_x_end) { + if (node_x[i].x > node_x[i + 1].x) { + SWAP(struct NodeX, node_x[i], node_x[i + 1]); + if (i != 0) { + i -= 1; + } + } + else { + i += 1; + } } } /* Fill the pixels between node pairs. */ - for (i = 0; i < nodes; i += 2) { - if (node_x[i] >= xmax) break; - if (node_x[i + 1] > xmin) { - if (node_x[i ] < xmin) node_x[i ] = xmin; - if (node_x[i + 1] > xmax) node_x[i + 1] = xmax; - -#if 0 - /* for many x/y calls */ - for (j = node_x[i]; j < node_x[i + 1]; j++) { - callback(j - xmin, pixel_y - ymin, userData); + for (int i = 0; i < node_x_len; i += 2) { + int x_src = node_x[i].x; + int x_dst = node_x[i + 1].x; + + if (x_src >= xmax) { + break; + } + + if (x_dst > xmin) { + if (x_src < xmin) { + x_src = xmin; + } + if (x_dst > xmax) { + x_dst = xmax; } -#else /* for single call per x-span */ - if (node_x[i] < node_x[i + 1]) { - callback(node_x[i] - xmin, node_x[i + 1] - xmin, pixel_y - ymin, userData); + if (x_src < x_dst) { + callback(x_src - xmin, x_dst - xmin, pixel_y - ymin, userData); } -#endif } } + + /* Clear finalized nodes in one pass, only when needed + * (avoids excessive array-resizing). */ + if (do_remove == true) { + int i_dst = 0; + for (int i_src = 0; i_src < node_x_len; i_src += 1) { + const int *s = span_y[node_x[i_src].span_y_index]; + const int *co = verts[s[1]]; + if (co[1] != pixel_y) { + if (i_dst != i_src) { + /* x is initialized for the next pixel_y (no need to adjust here) */ + node_x[i_dst].span_y_index = node_x[i_src].span_y_index; + } + i_dst += 1; + } + } + node_x_len = i_dst; + } + + /* Scan for new x-nodes */ + while ((span_y_index < span_y_len) && + (verts[span_y[span_y_index][0]][1] == pixel_y)) + { + /* note, node_x these are just added at the end, + * not ideal but sorting once will resolve. */ + + /* x is initialized for the next pixel_y */ + struct NodeX *n = &node_x[node_x_len++]; + n->span_y_index = span_y_index; + span_y_index += 1; + } } + + MEM_freeN(span_y); MEM_freeN(node_x); } |