Fix T65691: GPencil Drawing long strokes turn invisible

There was a fixed limit to the number of points available in a buffer stroke.

Now, the array is expanded as needed using a predefined number of points for each expansion, instead to add one by one. This is done to reduce the number of times the memory allocation is required.

As part of the fix, some variables have been renamed to reflect better their use.

1 files changed, 11 insertions, 14 deletions

diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil/gpencil_primitive.c
index ca77b209811..c79366e6a2b 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil/gpencil_primitive.c
@@ -114,16 +114,8 @@ static void gp_session_validatebuffer(tGPDprimitive *p)
   bGPdata *gpd = p->gpd;
 
   /* clear memory of buffer (or allocate it if starting a new session) */
-  if (gpd->runtime.sbuffer) {
-    memset(gpd->runtime.sbuffer, 0, sizeof(tGPspoint) * GP_STROKE_BUFFER_MAX);
-  }
-  else {
-    gpd->runtime.sbuffer = MEM_callocN(sizeof(tGPspoint) * GP_STROKE_BUFFER_MAX,
-                                       "gp_session_strokebuffer");
-  }
-
-  /* reset indices */
-  gpd->runtime.sbuffer_size = 0;
+  gpd->runtime.sbuffer = ED_gpencil_sbuffer_ensure(
+      gpd->runtime.sbuffer, &gpd->runtime.sbuffer_size, &gpd->runtime.sbuffer_used, true);
 
   /* reset flags */
   gpd->runtime.sbuffer_sflag = 0;
@@ -828,7 +820,7 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
     }
 
     /* Copy points to buffer */
-    tGPspoint *tpt = ((tGPspoint *)(gpd->runtime.sbuffer) + gpd->runtime.sbuffer_size);
+    tGPspoint *tpt = ((tGPspoint *)(gpd->runtime.sbuffer) + gpd->runtime.sbuffer_used);
 
     /* Store original points */
     float tmp_xyp[2];
@@ -927,10 +919,10 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
     tpt->time = p2d->time;
 
     /* point uv */
-    if (gpd->runtime.sbuffer_size > 0) {
+    if (gpd->runtime.sbuffer_used > 0) {
       MaterialGPencilStyle *gp_style = tgpi->mat->gp_style;
       const float pixsize = gp_style->texture_pixsize / 1000000.0f;
-      tGPspoint *tptb = (tGPspoint *)gpd->runtime.sbuffer + gpd->runtime.sbuffer_size - 1;
+      tGPspoint *tptb = (tGPspoint *)gpd->runtime.sbuffer + gpd->runtime.sbuffer_used - 1;
       bGPDspoint spt, spt2;
 
       /* get origin to reproject point */
@@ -958,7 +950,11 @@ static void gp_primitive_update_strokes(bContext *C, tGPDprimitive *tgpi)
 
     tpt->uv_rot = p2d->uv_rot;
 
-    gpd->runtime.sbuffer_size++;
+    gpd->runtime.sbuffer_used++;
+
+    /* check if still room in buffer or add more */
+    gpd->runtime.sbuffer = ED_gpencil_sbuffer_ensure(
+        gpd->runtime.sbuffer, &gpd->runtime.sbuffer_size, &gpd->runtime.sbuffer_used, false);
 
     /* add small offset to keep stroke over the surface */
     if ((depth_arr) && (gpd->zdepth_offset > 0.0f)) {
@@ -1078,6 +1074,7 @@ static void gpencil_primitive_exit(bContext *C, wmOperator *op)
     gpd->runtime.sbuffer = NULL;
 
     /* clear flags */
+    gpd->runtime.sbuffer_used = 0;
     gpd->runtime.sbuffer_size = 0;
     gpd->runtime.sbuffer_sflag = 0;
   }