GPencil: New Percentage parameter in Build modifier

Add a factor to determine the percentage affected.

This parameter is used to hide part of the stroke and to have a full control of how the points are displayed and not linked to current scene frame.

{F8526502}

{F8526511}

Reviewed By: mendio, pepeland

Differential Revision: https://developer.blender.org/D7682

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c b/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c
index c31f73df25d..71a051629d8 100644
--- a/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c
+++ b/source/blender/gpencil_modifiers/intern/MOD_gpencilbuild.c
@@ -406,6 +406,7 @@ static void generate_geometry(GpencilModifierData *md,
 {
   BuildGpencilModifierData *mmd = (BuildGpencilModifierData *)md;
   const bool reverse = (mmd->transition != GP_BUILD_TRANSITION_GROW);
+  const bool is_percentage = (mmd->flag & GP_BUILD_PERCENTAGE);
 
   const float ctime = DEG_get_ctime(depsgraph);
 
@@ -500,7 +501,8 @@ static void generate_geometry(GpencilModifierData *md,
   }
 
   /* Determine how far along we are between the keyframes */
-  float fac = (ctime - start_frame) / (end_frame - start_frame);
+  float fac = is_percentage ? mmd->percentage_fac :
+                              (ctime - start_frame) / (end_frame - start_frame);
 
   /* Time management mode */
   switch (mmd->mode) {