Armature: Add back Stick bone draw type.

The actual code is a bit convoluted but allows good and "pseudo efficient"
drawing. (pseudo efficient because rendering instances with that amount of
vertices is really inneficient. We should go full procedural but need to
have bufferTexture implemented first) But drawing speed is not a bottleneck
here and it's already a million time less crappy than the old (2.79) immediate
mode method.

Instead of drawing actual wires with different width we render a triangle
fan batch (containing 3 fans: bone, head, tail) which is then oriented in
screen space to the bone direction. We then interpolate a float value
accross vertices giving us a nice blend factor to blend the colors and
gives us really smooth interpolation inside the bone.

The outside edge still being geometry will be antialiased by MSAA if enabled.

1 files changed, 70 insertions, 4 deletions

diff --git a/source/blender/draw/intern/draw_armature.c b/source/blender/draw/intern/draw_armature.c
index 1a2ff70624b..efbf1143c16 100644
--- a/source/blender/draw/intern/draw_armature.c
+++ b/source/blender/draw/intern/draw_armature.c
@@ -82,6 +82,7 @@ static struct {
 	DRWShadingGroup *bone_box_wire;
 	DRWShadingGroup *bone_box_outline;
 	DRWShadingGroup *bone_wire_wire;
+	DRWShadingGroup *bone_stick;
 	DRWShadingGroup *bone_envelope_solid;
 	DRWShadingGroup *bone_envelope_distance;
 	DRWShadingGroup *bone_envelope_wire;
@@ -181,6 +182,20 @@ static void drw_shgroup_bone_wire_wire(const float (*bone_mat)[4], const float c
 	DRW_shgroup_call_dynamic_add(g_data.bone_wire_wire, final_bonemat, color);
 }
 
+static void drw_shgroup_bone_stick(
+        const float (*bone_mat)[4],
+        const float col_wire[4], const float col_bone[4], const float col_head[4], const float col_tail[4])
+{
+	if (g_data.bone_stick == NULL) {
+		g_data.bone_stick = shgroup_instance_bone_stick(g_data.passes.bone_wire);
+	}
+	float final_bonemat[4][4], tail[4];
+	mul_m4_m4m4(final_bonemat, g_data.ob->obmat, bone_mat);
+	add_v3_v3v3(tail, final_bonemat[3], final_bonemat[1]);
+	DRW_shgroup_call_dynamic_add(g_data.bone_stick, final_bonemat[3], tail, col_wire, col_bone, col_head, col_tail);
+}
+
+
 /* Envelope */
 static void drw_shgroup_bone_envelope_distance(
         const float (*bone_mat)[4],
@@ -1192,11 +1207,62 @@ static void draw_bone_envelope(
 }
 
 static void draw_bone_line(
-        EditBone *UNUSED(eBone), bPoseChannel *UNUSED(pchan), bArmature *UNUSED(arm),
-        const int UNUSED(boneflag), const short UNUSED(constflag),
-        const int UNUSED(select_id))
+        EditBone *eBone, bPoseChannel *pchan, bArmature *arm,
+        const int boneflag, const short constflag, const int select_id)
 {
-	/* work in progress  -- fclem */
+	const float *col_bone = get_bone_solid_with_consts_color(eBone, pchan, arm, boneflag, constflag);
+	const float *col_wire = get_bone_wire_color(eBone, pchan, arm, boneflag, constflag);
+	const float no_display[4] = {0.0f, 0.0f, 0.0f, 0.0f};
+	const float *col_head = no_display;
+	const float *col_tail = col_bone;
+
+	if (eBone) {
+		if (eBone->flag & BONE_TIPSEL) {
+			col_tail = g_theme.vertex_select_color;
+		}
+		if (boneflag & BONE_SELECTED) {
+			col_bone = g_theme.edge_select_color;
+		}
+		col_wire = g_theme.wire_color;
+	}
+
+	/*	Draw root point if we are not connected and parent are not hidden */
+	if ((BONE_FLAG(eBone, pchan) & BONE_CONNECTED) == 0) {
+		if (eBone && !(eBone->parent && !EBONE_VISIBLE(arm, eBone->parent))) {
+			col_head = (eBone->flag & BONE_ROOTSEL) ? g_theme.vertex_select_color : col_bone;
+		}
+		else if (pchan) {
+			Bone *bone = pchan->bone;
+			if (!(bone->parent && (bone->parent->flag & (BONE_HIDDEN_P | BONE_HIDDEN_PG)))) {
+				col_head = col_bone;
+			}
+		}
+	}
+
+	if (g_theme.const_color != NULL) {
+		col_wire = no_display; /* actually shrink the display. */
+		col_bone = col_head = col_tail = g_theme.const_color;
+	}
+
+	if (select_id == -1) {
+		/* Not in selection mode, draw everything at once. */
+		drw_shgroup_bone_stick(BONE_VAR(eBone, pchan, disp_mat), col_wire, col_bone, col_head, col_tail);
+	}
+	else {
+		/* In selection mode, draw bone, root and tip separatly. */
+		DRW_select_load_id(select_id | BONESEL_BONE);
+		drw_shgroup_bone_stick(BONE_VAR(eBone, pchan, disp_mat), col_wire, col_bone, no_display, no_display);
+
+		if (col_head[3] > 0.0f) {
+			DRW_select_load_id(select_id | BONESEL_ROOT);
+			drw_shgroup_bone_stick(BONE_VAR(eBone, pchan, disp_mat), col_wire, no_display, col_head, no_display);
+		}
+
+		DRW_select_load_id(select_id | BONESEL_TIP);
+		drw_shgroup_bone_stick(BONE_VAR(eBone, pchan, disp_mat), col_wire, no_display, no_display, col_tail);
+
+		DRW_select_load_id(-1);
+	}
 }
 
 static void draw_bone_wire(