Various fixes

resources/shaders/140/flat_clip.fs

@@ -0,0 +1,17 @@
+#version 140
+
+const vec3 ZERO = vec3(0.0, 0.0, 0.0);
+
+uniform vec4 uniform_color;
+
+in vec3 clipping_planes_dots;
+
+out vec4 out_color;
+
+void main()
+{
+    if (any(lessThan(clipping_planes_dots, ZERO)))
+        discard;
+
+    out_color = uniform_color;
+}

resources/shaders/140/flat_clip.vs

@@ -0,0 +1,23 @@
+#version 140
+
+uniform mat4 view_model_matrix;
+uniform mat4 projection_matrix;
+uniform mat4 volume_world_matrix;
+
+// Clipping plane, x = min z, y = max z. Used by the FFF and SLA previews to clip with a top / bottom plane.
+uniform vec2 z_range;
+// Clipping plane - general orientation. Used by the SLA gizmo.
+uniform vec4 clipping_plane;
+
+in vec3 v_position;
+
+out vec3 clipping_planes_dots;
+
+void main()
+{
+    // Fill in the scalars for fragment shader clipping. Fragments with any of these components lower than zero are discarded.
+    vec4 world_pos = volume_world_matrix * vec4(v_position, 1.0);
+    clipping_planes_dots = vec3(dot(world_pos, clipping_plane), world_pos.z - z_range.x, z_range.y - world_pos.z);
+
+    gl_Position = projection_matrix * view_model_matrix * vec4(v_position, 1.0);
+}

resources/shaders/140/gouraud.fs

@@ -34,8 +34,6 @@ uniform SlopeDetection slope;
 //BBS: add outline_color
 uniform bool is_outline;
 
-uniform bool offset_depth_buffer;
-
 #ifdef ENABLE_ENVIRONMENT_MAP
     uniform sampler2D environment_tex;
     uniform bool use_environment_tex;
@@ -97,9 +95,4 @@ void main()
 #endif
 	else
         gl_FragColor = vec4(vec3(intensity.y) + color * intensity.x, alpha);
-		
-    // In the support painting gizmo and the seam painting gizmo are painted triangles rendered over the already
-    // rendered object. To resolved z-fighting between previously rendered object and painted triangles, values
-    // inside the depth buffer are offset by small epsilon for painted triangles inside those gizmos.
-    gl_FragDepth = gl_FragCoord.z - (offset_depth_buffer ? EPSILON : 0.0);
 }

resources/shaders/140/mm_contour.fs

@@ -1,13 +1,8 @@
 #version 140
 
-const float EPSILON = 0.0001;
-
 uniform vec4 uniform_color;
 
 void main()
 {
     gl_FragColor = uniform_color;
-    // Values inside depth buffer for fragments of the contour of a selected area are offset
-    // by small epsilon to solve z-fighting between painted triangles and contour lines.
-    gl_FragDepth = gl_FragCoord.z - EPSILON;
 }

resources/shaders/140/mm_contour.vs

@@ -2,10 +2,14 @@
 
 uniform mat4 view_model_matrix;
 uniform mat4 projection_matrix;
+uniform float offset;
 
 in vec3 v_position;
 
 void main()
 {
-    gl_Position = projection_matrix * view_model_matrix * vec4(v_position, 1.0);
+    // Add small epsilon to z to solve z-fighting between painted triangles and contour lines.
+	vec4 clip_position = projection_matrix * view_model_matrix * vec4(v_position, 1.0);
+	clip_position.z -= offset * abs(clip_position.w);
+    gl_Position = clip_position;
 }