FIX: hidden Line Type Linux (#12364)

Fix(GCodeViewer): Resolve z-fighting for wipe, seam, and retract markers using shader depth bias

Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libvgcode/src/Shaders.hpp

@@ -90,7 +90,10 @@ static const char* Segments_Vertex_Shader =
 "    );\n"
 "  int id = vertex_id < 4 ? id_a : id_b;\n"
 "  vec3 endpoint_pos = vertex_id < 4 ? pos_a : pos_b;\n"
-"  vec3 height_width_angle = texelFetch(height_width_angle_tex, id).xyz;\n"
+"  vec4 hwa = texelFetch(height_width_angle_tex, id);\n"
+"  vec3 height_width_angle = hwa.xyz;\n"
+"  // ORCA: Extract bias from w component\n"
+"  float bias = hwa.w;\n"
 "#ifdef FIX_TWISTING\n"
 "  int closer_id = (dot(camera_position - pos_a, camera_position - pos_a) < dot(camera_position - pos_b, camera_position - pos_b)) ? id_a : id_b;\n"
 "  vec3 closer_pos = (closer_id == id_a) ? pos_a : pos_b;\n"
@@ -131,6 +134,8 @@ static const char* Segments_Vertex_Shader =
 "    }\n"
 "  }\n"
 "  vec3 eye_position = (view_matrix * vec4(pos, 1.0)).xyz;\n"
+"  // ORCA: Apply bias to z-position to avoid z-fighting\n"
+"  eye_position.z += bias;\n"
 "  vec3 eye_normal = (view_matrix * vec4(normalize(pos - endpoint_pos), 0.0)).xyz;\n"
 "  vec3 color_base = decode_color(texelFetch(color_tex, id).r);\n"
 "  color = color_base * lighting(eye_position, eye_normal);\n"
@@ -155,9 +160,11 @@ static const char* Options_Vertex_Shader =
 "const float light_front_diffuse = 0.6 * 0.3;\n"
 "const float ambient = 0.3;\n"
 "const float emission = 0.25;\n"
-#ifndef _WIN32
+#ifdef __APPLE__
+// ORCA: Use smaller scaling factor for macOS
 "const float scaling_factor = 0.75;\n"
 #else
+// ORCA: Increase seam marker size to 1.5 for Windows and Linux
 "const float scaling_factor = 1.5;\n"
 #endif
 "uniform mat4 view_matrix;\n"
@@ -185,7 +192,10 @@ static const char* Options_Vertex_Shader =
 "}\n"
 "void main() {\n"
 "  int id = int(texelFetch(segment_index_tex, gl_InstanceID).r);\n"
-"  vec2 height_width = texelFetch(height_width_angle_tex, id).xy;\n"
+"  vec4 hwa = texelFetch(height_width_angle_tex, id);\n"
+"  vec2 height_width = hwa.xy;\n"
+"  // ORCA: Extract bias from w component\n"
+"  float bias = hwa.w;\n"
 "  vec3 offset = texelFetch(position_tex, id).xyz - vec3(0.0, 0.0, 0.5 * height_width.x);\n"
 "  height_width *= scaling_factor;\n"
 "  mat3 scale_matrix = mat3(\n"
@@ -193,6 +203,8 @@ static const char* Options_Vertex_Shader =
 "    0.0, height_width.y, 0.0,\n"
 "    0.0, 0.0, height_width.x);\n"
 "  vec3 eye_position = (view_matrix * vec4(scale_matrix * in_position + offset, 1.0)).xyz;\n"
+"  // ORCA: Apply bias to z-position to avoid z-fighting\n"
+"  eye_position.z += bias;\n"
 "  vec3 eye_normal = (view_matrix * vec4(in_normal, 0.0)).xyz;\n"
 "  vec3 color_base = decode_color(texelFetch(color_tex, id).r);\n"
 "  color = color_base * lighting(eye_position, eye_normal);\n"

src/libvgcode/src/ViewerImpl.cpp

@@ -966,9 +966,18 @@ static void extract_pos_and_or_hwa(const std::vector<PathVertex>& vertices, floa
                 height = v.height;
                 width = v.width;
             }
+            
+            // ORCA: Set bias for wipes and options to avoid z-fighting
+            float bias = 0.0f;
+            if (v.is_wipe())
+                bias = 0.05f;
+            else if (v.is_option())
+                bias = 0.1f;
+
             // the last component is a dummy float to comply with GL_RGBA32F format
+            // ORCA: Pass bias to shader
             heights_widths_angles->push_back({ height, width,
-                std::atan2(prev_line[0] * this_line[1] - prev_line[1] * this_line[0], dot(prev_line, this_line)), 0.0f });
+                std::atan2(prev_line[0] * this_line[1] - prev_line[1] * this_line[0], dot(prev_line, this_line)), bias });
         }
     }
 }