Pixman uses y-x banded rectangles to represent regions. We use these
y-x banded rectangles to generate triangle fans, resulting in more
geometry than strictly necessary to draw the screen.
This patch combines the bands to reduce geometry for complex scenes.
---
src/gl-renderer.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 64 insertions(+), 3 deletions(-)
diff --git a/src/gl-renderer.c b/src/gl-renderer.c
index 076c242..40447c7 100644
--- a/src/gl-renderer.c
+++ b/src/gl-renderer.c
@@ -25,6 +25,7 @@
#include <GLES2/gl2.h>
#include <GLES2/gl2ext.h>
+#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
@@ -296,6 +297,55 @@ calculate_edges(struct weston_view *ev, pixman_box32_t
*rect,
return n;
}
+static bool
+merge_down(pixman_box32_t *a, pixman_box32_t *b, pixman_box32_t *merge)
+{
+ if (a->x1 == b->x1 && a->x2 == b->x2 && a->y1 == b->y2) {
+ merge->x1 = a->x1;
+ merge->x2 = a->x2;
+ merge->y1 = b->y1;
+ merge->y2 = a->y2;
+ return true;
+ }
+ return false;
+}
+
+static int
+compress_bands(pixman_box32_t *inrects, int nrects,
+ pixman_box32_t **outrects)
+{
+ bool merged;
+ pixman_box32_t *out, merge_rect;
+ int i, j, nout;
+
+ if (!nrects) {
+ *outrects = NULL;
+ return 0;
+ }
+
+ /* nrects is an upper bound - we're not too worried about
+ * allocating a little extra
+ */
+ out = malloc(sizeof(pixman_box32_t) * nrects);
+ out[0] = inrects[0];
+ nout = 1;
+ for (i = 1; i < nrects; i++) {
+ for (j = 0; j < nout; j++) {
+ merged = merge_down(&inrects[i], &out[j], &merge_rect);
+ if (merged) {
+ out[j] = merge_rect;
+ break;
+ }
+ }
+ if (!merged) {
+ out[nout] = inrects[i];
+ nout++;
+ }
+ }
+ *outrects = out;
+ return nout;
+}
+
static int
texture_region(struct weston_view *ev, pixman_region32_t *region,
pixman_region32_t *surf_region)
@@ -306,11 +356,20 @@ texture_region(struct weston_view *ev, pixman_region32_t
*region,
GLfloat *v, inv_width, inv_height;
unsigned int *vtxcnt, nvtx = 0;
pixman_box32_t *rects, *surf_rects;
- int i, j, k, nrects, nsurf;
-
- rects = pixman_region32_rectangles(region, &nrects);
+ pixman_box32_t *raw_rects;
+ int i, j, k, nrects, nsurf, raw_nrects;
+ bool used_band_compression;
+ raw_rects = pixman_region32_rectangles(region, &raw_nrects);
surf_rects = pixman_region32_rectangles(surf_region, &nsurf);
+ if (raw_nrects < 4) {
+ used_band_compression = false;
+ nrects = raw_nrects;
+ rects = raw_rects;
+ } else {
+ nrects = compress_bands(raw_rects, raw_nrects, &rects);
+ used_band_compression = true;
+ }
/* worst case we can have 8 vertices per rect (ie. clipped into
* an octagon):
*/
@@ -369,6 +428,8 @@ texture_region(struct weston_view *ev, pixman_region32_t
*region,
}
}
+ if (used_band_compression)
+ free(rects);
return nvtx;
}
--
2.1.1
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