GPencil: Add missing 2.82 Random Layer color removed in refactor

Use a single color by object in grease pencil is not practical because is necessary to see all layers.

To tint by layer, the layer tint parameter is used and not the material color as is done in other modes.

This function has been backported from 2.82 because was removed in the 2.83 refactor.

1 files changed, 26 insertions, 1 deletions

diff --git a/source/blender/draw/engines/gpencil/gpencil_cache_utils.c b/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
index f8f55843a29..1344b649dff 100644
--- a/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
+++ b/source/blender/draw/engines/gpencil/gpencil_cache_utils.c
@@ -33,6 +33,7 @@
 #include "BKE_lib_id.h"
 #include "BKE_object.h"
 
+#include "BLI_hash.h"
 #include "BLI_link_utils.h"
 #include "BLI_memblock.h"
 
@@ -234,6 +235,21 @@ static void gpencil_layer_final_tint_and_alpha_get(const GPENCIL_PrivateData *pd
   *r_alpha *= pd->xray_alpha;
 }
 
+/* Random color by layer. */
+static void gpencil_layer_random_color_get(const Object *ob,
+                                           const bGPDlayer *gpl,
+                                           float r_color[3])
+{
+  const float hsv_saturation = 0.7f;
+  const float hsv_value = 0.6f;
+
+  uint ob_hash = BLI_ghashutil_strhash_p_murmur(ob->id.name);
+  uint gpl_hash = BLI_ghashutil_strhash_p_murmur(gpl->info);
+  float hue = BLI_hash_int_01(ob_hash * gpl_hash);
+  float hsv[3] = {hue, hsv_saturation, hsv_value};
+  hsv_to_rgb_v(hsv, r_color);
+}
+
 GPENCIL_tLayer *gpencil_layer_cache_add(GPENCIL_PrivateData *pd,
                                         const Object *ob,
                                         const bGPDlayer *gpl,
@@ -375,7 +391,16 @@ GPENCIL_tLayer *gpencil_layer_cache_add(GPENCIL_PrivateData *pd,
     DRW_shgroup_uniform_float_copy(grp, "thicknessOffset", (float)gpl->line_change);
     DRW_shgroup_uniform_float_copy(grp, "thicknessWorldScale", thickness_scale);
     DRW_shgroup_uniform_float_copy(grp, "vertexColorOpacity", vert_col_opacity);
-    DRW_shgroup_uniform_vec4_copy(grp, "layerTint", layer_tint);
+
+    /* If random color type, need color by layer. */
+    float gpl_color[4];
+    copy_v4_v4(gpl_color, layer_tint);
+    if (pd->v3d_color_type == V3D_SHADING_RANDOM_COLOR) {
+      gpencil_layer_random_color_get(ob, gpl, gpl_color);
+      gpl_color[3] = 1.0f;
+    }
+    DRW_shgroup_uniform_vec4_copy(grp, "layerTint", gpl_color);
+
     DRW_shgroup_uniform_float_copy(grp, "layerOpacity", layer_alpha);
     DRW_shgroup_stencil_mask(grp, 0xFF);
   }