Fix drawing debug lines from behind clip plane

GabrielMajeri · May 18, 2019 · caf7343 · caf7343
1 parent cba60ab
commit caf7343
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Showing 4 changed files with 25 additions and 22 deletions.
diff --git a/amethyst_rendy/shaders/vertex/debug_lines.vert b/amethyst_rendy/shaders/vertex/debug_lines.vert
@@ -24,20 +24,27 @@ layout(location = 0) out VertexData {
 } vertex;
 
 void main() {
+    float factor = float((gl_VertexIndex & 2) >> 1);
+    vertex.color = mix(color_a, color_b, factor);
 
     mat4 proj_view = proj * view;
     vec4 projected_a = proj_view * vec4(position_a, 1.0);
     vec4 projected_b = proj_view * vec4(position_b, 1.0);
-    vec2 screen_a = projected_a.xy / projected_a.w;
-    vec2 screen_b = projected_b.xy / projected_b.w;
-
-    vec2 normal = normalize((screen_b - screen_a)) * dir_mats[gl_VertexIndex & 1];
-    float factor = float((gl_VertexIndex & 2) >> 1);
-
-    normal *= mix(projected_a.w, projected_b.w, factor) * 1.0;
-    normal.x /= screen_space_thickness.x;
-    normal.y /= screen_space_thickness.y;
-
-    vertex.color = mix(color_a, color_b, factor);
-    gl_Position = mix(projected_a, projected_b, factor) + vec4(normal, 0.0, 0.0);
+    vec4 proj_current = mix(projected_a, projected_b, factor);
+
+    if (proj_current.w < 0) {
+        // vertex behind camera clip plane
+        vec4 proj_next = mix(projected_b, projected_a, factor);
+        vec3 clip_space_dir =  normalize(proj_current.xyw - proj_next.xyw);
+        float coef = -proj_current.w / clip_space_dir.z;
+        vec3 intersect_pos = proj_current.xyw + (clip_space_dir * coef);
+        gl_Position = vec4(intersect_pos.x, intersect_pos.y, 0, intersect_pos.z);
+    } else {
+        vec2 screen_a = projected_a.xy / projected_a.w;
+        vec2 screen_b = projected_b.xy / projected_b.w;
+        vec2 dir = normalize(screen_b - screen_a);
+        vec2 normal = dir * dir_mats[gl_VertexIndex & 1];
+        normal *= proj_current.w * screen_space_thickness;
+        gl_Position = proj_current + vec4(normal, 0.0, 0.0);
+    }
 }
diff --git a/amethyst_rendy/src/pass/debug_lines.rs b/amethyst_rendy/src/pass/debug_lines.rs
@@ -135,8 +135,8 @@ impl<B: Backend> RenderGroup<B, Resources> for DrawDebugLines<B> {
             index,
             DebugLinesArgs {
                 screen_space_thickness: [
-                    self.framebuffer_width / (line_width * 2.0),
-                    self.framebuffer_height / (line_width * 2.0),
+                    (line_width * 2.0) / self.framebuffer_width,
+                    (line_width * 2.0) / self.framebuffer_height,
                 ]
                 .into(),
             }

diff --git a/examples/assets/prefab/renderable.ron b/examples/assets/prefab/renderable.ron
@@ -11,12 +11,11 @@ Prefab (
                 graphics: (
                     mesh: Asset(File("mesh/lid.obj", ("OBJ", ()))),
                     material: (
-                        albedo: Generate(Srgba(1.0, 0.0, 0.0, 1.0)),
+                        albedo: Generate(Srgba(0.0, 0.0, 1.0, 1.0)),
                     ),
                 ),
                 transform: (
                     translation: (5.0, 1.0, 5.0),
-                    // rotation: (0.5, -0.5, -0.5, 0.5),
                 ),
             ),
         ),
@@ -25,12 +24,11 @@ Prefab (
                 graphics: (
                     mesh: Asset(File("mesh/teapot.obj", ("OBJ", ()))),
                     material: (
-                        albedo: Generate(Srgba(1.0, 0.0, 0.0, 1.0)),
+                        albedo: Generate(Srgba(0.0, 1.0, 0.0, 1.0)),
                     ),
                 ),
                 transform: (
                     translation: (5.0, 1.0, 5.0),
-                    // rotation: (0.5, -0.5, -0.5, 0.5),
                 ),
             ),
         ),
@@ -136,9 +134,7 @@ Prefab (
         (
             data: (
                 transform: Transform (
-                    translation: (0.0, 10.0, 20.0),
-                    // translation: (0.0, 0.0, 20.0),
-                    // rotation: (0.6087614, 0.0, 0.0, 0.7933533),
+                    translation: (0.0, 20.0, 20.0),
                     rotation: (-0.4, 0.0, 0.0, 0.862),
 
                 ),

diff --git a/examples/custom_game_data/main.rs b/examples/custom_game_data/main.rs
@@ -10,7 +10,7 @@ use amethyst::{
     },
     core::transform::TransformBundle,
     ecs::{
-        prelude::{Component, Entity, ReadExpect, Resources, System, SystemData},
+        prelude::{Component, Entity, ReadExpect, Resources, SystemData},
         NullStorage,
     },
     input::{is_close_requested, is_key_down, InputBundle, StringBindings},