Implement correct culling in the viewer

Using the DS's polygon attribute field.

src/info/mod.rs

@@ -64,6 +64,14 @@ fn model_info(db: &Database, model_id: usize) {
                 }
             }
         }
+        println!("      Culling Mode: {}",
+            match (material.cull_backface, material.cull_frontface) {
+                (true, true) => "Cull All",
+                (true, false) => "Cull Backfacing",
+                (false, true) => "Cull Frontfacing",
+                (false, false) => "No Culling",
+            }
+        );
     }
     println!();
 }

src/nitro/model.rs

@@ -25,6 +25,8 @@ pub struct Material {
     pub params: TextureParameters,
     pub width: u16,
     pub height: u16,
+    pub cull_backface: bool,
+    pub cull_frontface: bool,
     pub texture_mat: Matrix4<f64>,
 }
 
@@ -176,6 +178,9 @@ fn read_material(cur: Cur, name: Name) -> Result<Material> {
 
     let params = TextureParameters::from_u32(params);
 
+    let cull_backface = polygon_attr.bits(6,7) == 0;
+    let cull_frontface = polygon_attr.bits(7,8) == 0;
+
     // For now, use the section size to determine whether there
     // is texture matrix data.
     let texture_mat = match section_size {
@@ -196,6 +201,8 @@ fn read_material(cur: Cur, name: Name) -> Result<Material> {
         params,
         width,
         height,
+        cull_backface,
+        cull_frontface,
         texture_mat,
     })
 }

src/viewer/draw.rs

@@ -1,9 +1,7 @@
 use cgmath::Matrix4;
 use errors::Result;
 use primitives::{Primitives, Vertex};
-use glium::{self, VertexBuffer, IndexBuffer,
-    Display, Frame, DrawParameters, Surface,
-};
+use glium::{self, VertexBuffer, IndexBuffer, Display, Frame, Surface};
 use glium::texture::Texture2d;
 use viewer::gl_context::GlContext;
 use viewer::state::ViewState;
@@ -85,7 +83,6 @@ impl DrawingData {
         db: &Database,
         ctx: &GlContext,
         target: &mut Frame,
-        draw_params: &DrawParameters
     ) {
         if let Ok(ref gl_prims) = self.gl_prims {
             let model = &db.models[self.view_state.model_id];
@@ -93,6 +90,8 @@ impl DrawingData {
             let mvp = self.view_state.eye.model_view_persp();
 
             for call in &gl_prims.primitives.draw_calls {
+                let material = &model.materials[call.mat_id as usize];
+
                 let texture =
                     match self.textures[call.mat_id as usize] {
                         Ok(Some(ref tex)) => tex,
@@ -116,7 +115,7 @@ impl DrawingData {
                             (true, true) => SamplerWrapFunction::Mirror,
                         }
                     };
-                    let params = &model.materials[call.mat_id as usize].params;
+                    let params = &material.params;
                     s.1.wrap_function.0 = wrap_fn(params.repeat_s, params.mirror_s);
                     s.1.wrap_function.1 = wrap_fn(params.repeat_t, params.mirror_t);
 
@@ -136,12 +135,30 @@ impl DrawingData {
                 let indices = &gl_prims.index_buffer
                     .slice(call.index_range.clone()).unwrap();
 
+                let draw_params = glium::DrawParameters {
+                    depth: glium::Depth {
+                        test: glium::draw_parameters::DepthTest::IfLess,
+                        write: true,
+                        .. Default::default()
+                    },
+                    backface_culling: {
+                        use glium::draw_parameters::BackfaceCullingMode as Mode;
+                        match (material.cull_backface, material.cull_frontface) {
+                            (false, false) => Mode::CullingDisabled,
+                            (true, false) => Mode::CullClockwise,
+                            (false, true) => Mode::CullCounterClockwise,
+                            (true, true) => continue,
+                        }
+                    },
+                    .. Default::default()
+                };
+
                 target.draw(
                     &gl_prims.vertex_buffer,
                     indices,
                     &ctx.program,
                     &uniforms,
-                    draw_params,
+                    &draw_params,
                 ).unwrap();
             }
         }

src/viewer/ui.rs

@@ -286,23 +286,7 @@ impl Ui {
         } else {
             let middle_grey = (0.4666, 0.4666, 0.4666, 1.0);
             target.clear_color_srgb_and_depth(middle_grey, 1.0);
-
-            let draw_params = glium::DrawParameters {
-                depth: glium::Depth {
-                    test: glium::draw_parameters::DepthTest::IfLess,
-                    write: true,
-                    .. Default::default()
-                },
-                backface_culling: glium::draw_parameters::BackfaceCullingMode::CullClockwise,
-                .. Default::default()
-            };
-
-            self.drawing_data.draw(
-                &self.db,
-                &self.ctx,
-                &mut target,
-                &draw_params,
-            );
+            self.drawing_data.draw(&self.db, &self.ctx, &mut target);
         }
 
         target.finish().unwrap();