Curve Edit: Cleanup/Improve/Fix handles drawing

Now handles are drawn using index buffer instead of duplicating memory
requirement.

Also make use of shader tricks to draw handles antialiased, and respond to
UI scalling.

Make vertex point match edit mesh vertex size.

1 files changed, 55 insertions, 49 deletions

diff --git a/source/blender/draw/modes/shaders/edit_curve_overlay_handle_geom.glsl b/source/blender/draw/modes/shaders/edit_curve_overlay_handle_geom.glsl
index 9da8d9b50d7..734691a02b0 100644
--- a/source/blender/draw/modes/shaders/edit_curve_overlay_handle_geom.glsl
+++ b/source/blender/draw/modes/shaders/edit_curve_overlay_handle_geom.glsl
@@ -1,14 +1,30 @@
 
-#define ACTIVE_NURB    1 << 7 /* Keep the same value of `ACTIVE_NURB` in `draw_cache_imp_curve.c` */
+#define VERTEX_ACTIVE   1 << 0
+#define VERTEX_SELECTED 1 << 1
+#define ACTIVE_NURB     1 << 2 /* Keep the same value of `ACTIVE_NURB` in `draw_cache_imp_curve.c` */
+#define NURBS_EDGE_SELECTED (((vertFlag[1] & vertFlag[0]) & VERTEX_SELECTED) != 0)
 
 layout(lines) in;
-layout(line_strip, max_vertices = 6) out;
+layout(triangle_strip, max_vertices = 10) out;
 
 uniform vec2 viewportSize;
 
 flat in int vertFlag[];
 
-flat out vec4 finalColor;
+out vec4 finalColor;
+
+void output_line(vec2 offset, vec4 color)
+{
+	finalColor = color;
+
+	gl_Position = gl_in[0].gl_Position;
+	gl_Position.xy += offset * gl_in[0].gl_Position.w;
+	EmitVertex();
+
+	gl_Position = gl_in[1].gl_Position;
+	gl_Position.xy += offset * gl_in[1].gl_Position.w;
+	EmitVertex();
+}
 
 void main()
 {
@@ -17,63 +33,53 @@ void main()
 	vec4 v1 = gl_in[0].gl_Position;
 	vec4 v2 = gl_in[1].gl_Position;
 
-	int is_active_nurb = vertFlag[1] & ACTIVE_NURB;
-	int color_id = vertFlag[1] ^ is_active_nurb;
+	int is_active_nurb = (vertFlag[1] & ACTIVE_NURB);
+	int color_id = (vertFlag[1] >> 3);
 
-	if (is_active_nurb != 0) {
-		/* draw the outline. */
-		vec2 v1_2 = (v2.xy/v2.w - v1.xy/v1.w);
-		vec2 offset;
 
-		if (abs(v1_2.x * viewportSize.x) < abs(v1_2.y * viewportSize.y)) {
-			offset = vec2(2.0 / viewportSize.x, 0.0);
-		}
-		else {
-			offset = vec2(0.0, 2.0 / viewportSize.y);
-		}
+	bool edge_selected = (((vertFlag[1] | vertFlag[0]) & VERTEX_SELECTED) != 0);
 
-		finalColor = colorActiveSpline;
+	vec4 inner_color;
+	if      (color_id == 0) inner_color = (edge_selected) ? colorHandleSelFree : colorHandleFree;
+	else if (color_id == 1) inner_color = (edge_selected) ? colorHandleSelAuto : colorHandleAuto;
+	else if (color_id == 2) inner_color = (edge_selected) ? colorHandleSelVect : colorHandleVect;
+	else if (color_id == 3) inner_color = (edge_selected) ? colorHandleSelAlign : colorHandleAlign;
+	else if (color_id == 4) inner_color = (edge_selected) ? colorHandleSelAutoclamp : colorHandleAutoclamp;
+	else                    inner_color = (NURBS_EDGE_SELECTED) ? colorNurbSelUline : colorNurbUline;
 
-		gl_Position = v1;
-		gl_Position.xy += offset * v1.w;
-		EmitVertex();
+	vec4 outer_color = (is_active_nurb != 0)
+	                   ? mix(colorActiveSpline, inner_color, 0.25) /* Minimize active color bleeding on inner_color. */
+	                   : vec4(inner_color.rgb, 0.0);
 
-		gl_Position = v2;
-		gl_Position.xy += offset * v2.w;
-		EmitVertex();
+	vec2 v1_2 = (v2.xy/v2.w - v1.xy/v1.w);
+	vec2 offset = sizeEdge * 4.0 / viewportSize; /* 4.0 is eyeballed */
 
-		EndPrimitive();
+	if (abs(v1_2.x * viewportSize.x) < abs(v1_2.y * viewportSize.y)) {
+		offset.y = 0.0;
+	}
+	else {
+		offset.x = 0.0;
+	}
 
-		gl_Position = v1;
-		gl_Position.xy -= offset * v1.w;
-		EmitVertex();
+	/* draw the transparent border (AA). */
+	if (is_active_nurb != 0) {
+		offset *= 0.75; /* Don't make the active "halo" appear very thick. */
+		output_line(offset * 2.0, vec4(colorActiveSpline.rgb, 0.0));
+	}
 
-		gl_Position = v2;
-		gl_Position.xy -= offset * v2.w;
-		EmitVertex();
+	/* draw the outline. */
+	output_line(offset, outer_color);
 
-		EndPrimitive();
-	}
+	/* draw the core of the line. */
+	output_line(vec2(0.0), inner_color);
 
-	if      (color_id == 0)  finalColor = colorHandleFree;
-	else if (color_id == 1)  finalColor = colorHandleAuto;
-	else if (color_id == 2)  finalColor = colorHandleVect;
-	else if (color_id == 3)  finalColor = colorHandleAlign;
-	else if (color_id == 4)  finalColor = colorHandleAutoclamp;
-	else if (color_id == 5)  finalColor = colorHandleSelFree;
-	else if (color_id == 6)  finalColor = colorHandleSelAuto;
-	else if (color_id == 7)  finalColor = colorHandleSelVect;
-	else if (color_id == 8)  finalColor = colorHandleSelAlign;
-	else if (color_id == 9)  finalColor = colorHandleSelAutoclamp;
-	else if (color_id == 10) finalColor = colorNurbUline;
-	else if (color_id == 11) finalColor = colorNurbSelUline;
-	else                     finalColor = colorVertexSelect;
-
-	gl_Position = v1;
-	EmitVertex();
+	/* draw the outline. */
+	output_line(-offset, outer_color);
 
-	gl_Position = v2;
-	EmitVertex();
+	/* draw the transparent border (AA). */
+	if (is_active_nurb != 0) {
+		output_line(offset * -2.0, vec4(colorActiveSpline.rgb, 0.0));
+	}
 
 	EndPrimitive();
 }