GP: New Cutter, Constraints and Segment selection

This commit groups a set of new tools that were tested in grease pencil object branch before moving to master. We decide to do all the development in a separated branch because it could break master during days or weeks before the new tools were ready to deploy.

The commit includes:

- New Cutter tool to trim strokes and help cleaning up drawings.

- New set of constraints and guides to draw different types of shapes. All the credits for this development goes to Charlie Jolly (@charlie), thanks for your help!

- Segment selection mode to select strokes between intersections.

- New operator to change strokes cap mode.

- New option to display only keyframed frames. This option is very important when fill strokes with color.

- Multiple small fixes and tweaks.

Thanks to @pepeland and @mendio for their ideas, tests, reviews and support.

Note: Still pending the final icons for Cutter in Toolbar and Segment Selection in Topbar. @billreynish could help us here?

4 files changed, 69 insertions, 14 deletions

diff --git a/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c b/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
index beb9f3ee847..b7207b6af65 100644
--- a/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
+++ b/source/blender/draw/engines/gpencil/gpencil_draw_cache_impl.c
@@ -390,6 +390,14 @@ GPUBatch *DRW_gpencil_get_buffer_ctrlpoint_geom(bGPdata *gpd)
 	bGPDcontrolpoint *cps = gpd->runtime.cp_points;
 	int totpoints = gpd->runtime.tot_cp_points;
 
+	const DRWContextState *draw_ctx = DRW_context_state_get();
+	Scene *scene = draw_ctx->scene;
+	ToolSettings *ts = scene->toolsettings;
+
+	if (ts->gp_sculpt.guide.use_guide) {
+		totpoints++;
+	}
+	
 	static GPUVertFormat format = { 0 };
 	static uint pos_id, color_id, size_id;
 	if (format.attr_len == 0) {
@@ -415,6 +423,27 @@ GPUBatch *DRW_gpencil_get_buffer_ctrlpoint_geom(bGPdata *gpd)
 		idx++;
 	}
 
+	if (ts->gp_sculpt.guide.use_guide) {
+		float size = 10 * 0.8f;
+		float color[4];
+		float position[3];
+		if (ts->gp_sculpt.guide.reference_point == GP_GUIDE_REF_CUSTOM) {
+			UI_GetThemeColor4fv(TH_GIZMO_PRIMARY, color);
+			copy_v3_v3(position, ts->gp_sculpt.guide.location);
+		}
+		else if (ts->gp_sculpt.guide.reference_point == GP_GUIDE_REF_OBJECT && ts->gp_sculpt.guide.reference_object != NULL) {
+			UI_GetThemeColor4fv(TH_GIZMO_SECONDARY, color);
+			copy_v3_v3(position, ts->gp_sculpt.guide.reference_object->loc);
+		}
+		else {
+			UI_GetThemeColor4fv(TH_REDALERT, color);
+			copy_v3_v3(position, scene->cursor.location);
+		}
+		GPU_vertbuf_attr_set(vbo, pos_id, idx, position);
+		GPU_vertbuf_attr_set(vbo, size_id, idx, &size);
+		GPU_vertbuf_attr_set(vbo, color_id, idx, color);
+	}
+
 	return GPU_batch_create_ex(GPU_PRIM_POINTS, vbo, NULL, GPU_BATCH_OWNS_VBO);
 }
 
diff --git a/source/blender/draw/engines/gpencil/gpencil_draw_utils.c b/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
index 2e9a212170c..f925f9fb506 100644
--- a/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
+++ b/source/blender/draw/engines/gpencil/gpencil_draw_utils.c
@@ -357,7 +357,7 @@ bool DRW_gpencil_onion_active(bGPdata *gpd)
 /* create shading group for strokes */
 DRWShadingGroup *DRW_gpencil_shgroup_stroke_create(
         GPENCIL_e_data *e_data, GPENCIL_Data *vedata, DRWPass *pass, GPUShader *shader, Object *ob,
-        bGPdata *gpd, MaterialGPencilStyle *gp_style, int id, bool onion)
+        bGPdata *gpd, bGPDstroke *gps, MaterialGPencilStyle *gp_style, int id, bool onion)
 {
 	GPENCIL_StorageList *stl = ((GPENCIL_Data *)vedata)->stl;
 	const float *viewport_size = DRW_viewport_size_get();
@@ -391,6 +391,10 @@ DRWShadingGroup *DRW_gpencil_shgroup_stroke_create(
 		}
 		DRW_shgroup_uniform_int(grp, "color_type", &stl->shgroups[id].color_type, 1);
 		DRW_shgroup_uniform_float(grp, "pixfactor", &gpd->pixfactor, 1);
+
+		stl->shgroups[id].caps_mode[0] = gps->caps[0];
+		stl->shgroups[id].caps_mode[1] = gps->caps[1];
+		DRW_shgroup_uniform_int(grp, "caps_mode", &stl->shgroups[id].caps_mode[0], 2);
 	}
 	else {
 		stl->storage->obj_scale = 1.0f;
@@ -405,6 +409,8 @@ DRWShadingGroup *DRW_gpencil_shgroup_stroke_create(
 		else {
 			DRW_shgroup_uniform_float(grp, "pixfactor", &stl->storage->pixfactor, 1);
 		}
+		const int zero[2] = { 0, 0 };
+		DRW_shgroup_uniform_int(grp, "caps_mode", &zero[0], 2);
 	}
 
 	if ((gpd) && (id > -1)) {
@@ -1177,7 +1183,8 @@ void DRW_gpencil_populate_buffer_strokes(GPENCIL_e_data *e_data, void *vedata, T
 			if (gpd->runtime.sbuffer_size > 1) {
 				if ((gp_style) && (gp_style->mode == GP_STYLE_MODE_LINE)) {
 					stl->g_data->shgrps_drawing_stroke = DRW_gpencil_shgroup_stroke_create(
-						e_data, vedata, psl->drawing_pass, e_data->gpencil_stroke_sh, NULL, gpd, gp_style, -1, false);
+						e_data, vedata, psl->drawing_pass, e_data->gpencil_stroke_sh, NULL,
+						gpd, NULL, gp_style, -1, false);
 				}
 				else {
 					stl->g_data->shgrps_drawing_stroke = DRW_gpencil_shgroup_point_create(
@@ -1240,13 +1247,14 @@ void DRW_gpencil_populate_buffer_strokes(GPENCIL_e_data *e_data, void *vedata, T
 		}
 	}
 
-	/* control points */
-	if ((overlay) && (gpd->runtime.tot_cp_points > 0) &&
-	    ((gpd->runtime.sbuffer_sflag & GP_STROKE_ERASER) == 0) &&
-	    ((v3d->gizmo_flag & V3D_GIZMO_HIDE) == 0) &&
-	    ((v3d->gizmo_flag & V3D_GIZMO_HIDE_TOOL) == 0))
-	{
+	/* control points for primitives and speed guide */
+	const bool is_cppoint = (gpd->runtime.tot_cp_points > 0);
+	const bool is_speed_guide = (ts->gp_sculpt.guide.use_guide && (draw_ctx->object_mode == OB_MODE_PAINT_GPENCIL));
+	const bool is_show_gizmo = (((v3d->gizmo_flag & V3D_GIZMO_HIDE) == 0) && ((v3d->gizmo_flag & V3D_GIZMO_HIDE_TOOL) == 0));
 
+	if ((overlay) && (is_cppoint || is_speed_guide) && (is_show_gizmo) &&
+		((gpd->runtime.sbuffer_sflag & GP_STROKE_ERASER) == 0))
+	{
 		DRWShadingGroup *shgrp = DRW_shgroup_create(
 			e_data->gpencil_edit_point_sh, psl->drawing_pass);
 		const float *viewport_size = DRW_viewport_size_get();
@@ -1357,7 +1365,7 @@ static void DRW_gpencil_shgroups_create(
 
 				shgrp = DRW_gpencil_shgroup_stroke_create(
 				        e_data, vedata, psl->stroke_pass, e_data->gpencil_stroke_sh,
-				        ob, gpd, gp_style, stl->storage->shgroup_id, elm->onion);
+				        ob, gpd, gps, gp_style, stl->storage->shgroup_id, elm->onion);
 
 				DRW_shgroup_call_range_add(
 				        shgrp, cache->b_stroke.batch,
@@ -1472,7 +1480,7 @@ void DRW_gpencil_populate_multiedit(
 	ToolSettings *ts = scene->toolsettings;
 
 	/* check if playing animation */
-	bool playing = stl->storage->is_playing;
+	const bool playing = stl->storage->is_playing;
 
 	/* calc max size of VBOs */
 	gpencil_calc_vertex(stl, cache_ob, cache, gpd, cfra_eval);
@@ -1541,7 +1549,7 @@ void DRW_gpencil_populate_datablock(
 	bGPDlayer *gpl_active = BKE_gpencil_layer_getactive(gpd);
 
 	/* check if playing animation */
-	bool playing = stl->storage->is_playing;
+	const bool playing = stl->storage->is_playing;
 
 	GpencilBatchCache *cache = gpencil_batch_cache_get(ob, cfra_eval);
 
@@ -1567,6 +1575,10 @@ void DRW_gpencil_populate_datablock(
 			continue;
 		}
 
+		const bool is_solomode = GPENCIL_PAINT_MODE(gpd) &&
+			(!playing) && (!stl->storage->is_render) &&
+			(gpl->flag & GP_LAYER_SOLO_MODE);
+
 		/* filter view layer to gp layers in the same view layer (for compo) */
 		if ((stl->storage->is_render) && (gpl->viewlayername[0] != '\0')) {
 			if (!STREQ(view_layer->name, gpl->viewlayername)) {
@@ -1586,6 +1598,11 @@ void DRW_gpencil_populate_datablock(
 		if (gpf == NULL)
 			continue;
 
+		/* if solo mode, display only frames with keyframe in the current frame */
+		if ((is_solomode) && (gpf->framenum != remap_cfra)) {
+			continue;
+		}
+
 		opacity = gpl->opacity;
 		/* if pose mode, maybe the overlay to fade geometry is enabled */
 		if ((draw_ctx->obact) && (draw_ctx->object_mode == OB_MODE_POSE) &&
diff --git a/source/blender/draw/engines/gpencil/gpencil_engine.h b/source/blender/draw/engines/gpencil/gpencil_engine.h
index 6f2b40136ca..c560321df9f 100644
--- a/source/blender/draw/engines/gpencil/gpencil_engine.h
+++ b/source/blender/draw/engines/gpencil/gpencil_engine.h
@@ -114,6 +114,7 @@ typedef struct GPENCIL_shgroup {
 	int texture_clamp;
 	int fill_style;
 	int keep_size;
+	int caps_mode[2];
 	float obj_scale;
 } GPENCIL_shgroup;
 
@@ -364,7 +365,8 @@ typedef struct GpencilBatchCache {
 /* general drawing functions */
 struct DRWShadingGroup *DRW_gpencil_shgroup_stroke_create(
         struct GPENCIL_e_data *e_data, struct GPENCIL_Data *vedata, struct DRWPass *pass, struct GPUShader *shader,
-        struct Object *ob, struct bGPdata *gpd, struct MaterialGPencilStyle *gp_style, int id, bool onion);
+        struct Object *ob, struct bGPdata *gpd, struct bGPDstroke *gps,
+		struct MaterialGPencilStyle *gp_style, int id, bool onion);
 void DRW_gpencil_populate_datablock(
         struct GPENCIL_e_data *e_data, void *vedata,
         struct Object *ob, struct tGPencilObjectCache *cache_ob);
diff --git a/source/blender/draw/engines/gpencil/shaders/gpencil_stroke_geom.glsl b/source/blender/draw/engines/gpencil/shaders/gpencil_stroke_geom.glsl
index c2a5f6b0b84..ad85046487b 100644
--- a/source/blender/draw/engines/gpencil/shaders/gpencil_stroke_geom.glsl
+++ b/source/blender/draw/engines/gpencil/shaders/gpencil_stroke_geom.glsl
@@ -2,6 +2,7 @@ uniform mat4 ModelViewProjectionMatrix;
 uniform vec2 Viewport;
 uniform int xraymode;
 uniform int color_type;
+uniform int caps_mode[2];
 
 layout(lines_adjacency) in;
 layout(triangle_strip, max_vertices = 13) out;
@@ -23,6 +24,8 @@ out vec2 uvfac;
 #define GPENCIL_COLOR_TEXTURE 1
 #define GPENCIL_COLOR_PATTERN 2
 
+#define GPENCIL_FLATCAP 1
+
 /* project 3d point to 2d on screen space */
 vec2 toScreenSpace(vec4 vertex)
 {
@@ -159,7 +162,9 @@ void main(void)
 	}
 
 	/* generate the start endcap */
-	if (is_equal(P0,P2) && (color_type == GPENCIL_COLOR_SOLID)){
+	if ((caps_mode[0] != GPENCIL_FLATCAP) && is_equal(P0,P2) &&
+		(color_type == GPENCIL_COLOR_SOLID))
+	{
 		vec4 cap_color = finalColor[1];
 
 		mTexCoord = vec2(2.0, 1.0);
@@ -205,7 +210,9 @@ void main(void)
 	EmitVertex();
 
 	/* generate the end endcap */
-	if (is_equal(P1,P3) && (color_type == GPENCIL_COLOR_SOLID) && (finaluvdata[2].x > 0)){
+	if ((caps_mode[1] != GPENCIL_FLATCAP) && is_equal(P1,P3) &&
+		(color_type == GPENCIL_COLOR_SOLID) && (finaluvdata[2].x > 0))
+	{
 		vec4 cap_color = finalColor[2];
 
 		mTexCoord = vec2(finaluvdata[2].x, 2.0);