Weight Paint Overlay: Refactor wire drawing

This reduce the number of batch/data needed. Stores a select/visiblee
flag inside the vert/loop normals.

1 files changed, 20 insertions, 3 deletions

diff --git a/source/blender/draw/modes/shaders/paint_wire_vert.glsl b/source/blender/draw/modes/shaders/paint_wire_vert.glsl
index 253c21745e2..a92591b957d 100644
--- a/source/blender/draw/modes/shaders/paint_wire_vert.glsl
+++ b/source/blender/draw/modes/shaders/paint_wire_vert.glsl
@@ -2,13 +2,30 @@
 uniform mat4 ModelViewProjectionMatrix;
 
 in vec3 pos;
-in int data;
+in vec4 nor; /* flag stored in w */
 
-flat out int finalFlag;
+flat out vec4 finalColor;
 
 void main()
 {
+	bool is_select = (nor.w > 0.0);
+	bool is_hidden = (nor.w < 0.0);
 	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+	/* Add offset in Z to avoid zfighting and render selected wires on top. */
+	/* TODO scale this bias using znear and zfar range. */
+	gl_Position.zw -= exp2(-20) * (is_select ? 2.0 : 1.0);
 
-	finalFlag = data;
+	if (is_hidden) {
+		gl_Position = vec4(-2.0, -2.0, -2.0, 1.0);
+	}
+
+#ifdef VERTEX_MODE
+	vec4 colSel = colorEdgeSelect;
+	colSel.rgb = clamp(colSel.rgb - 0.2, 0.0, 1.0);
+#else
+	const vec4 colSel = vec4(1.0, 1.0, 1.0, 1.0);
+#endif
+
+	finalColor = (is_select) ? colSel : colorWire;
+	finalColor.a = nor.w;
 }