feat(shaders): add ray_sphere snippet, use in gbuf_raster impostor

1 files changed, 4 insertions, 8 deletions

diff --git a/cnn_v3/shaders/gbuf_raster.wgsl b/cnn_v3/shaders/gbuf_raster.wgsl
index fa2dfd5..aed0e72 100644
--- a/cnn_v3/shaders/gbuf_raster.wgsl
+++ b/cnn_v3/shaders/gbuf_raster.wgsl
@@ -5,6 +5,7 @@
 
 #include "common_uniforms"
 #include "math/normal"
+#include "ray_sphere"
 
 @group(0) @binding(0) var<uniform> globals: GlobalUniforms;
 @group(0) @binding(1) var<storage, read> object_data: ObjectsBuffer;
@@ -93,14 +94,9 @@ fn fs_main(in: VertexOutput) -> GBufOutput {
         let sphere_radius = length(obj.model[0].xyz);  // uniform scale in col0
         let cam_pos = globals.camera_pos_time.xyz;
         let rd = normalize(in.world_pos - cam_pos);
-        let oc = cam_pos - sphere_center;
-        let b  = dot(oc, rd);
-        let c  = dot(oc, oc) - sphere_radius * sphere_radius;
-        let disc = b * b - c;
-        if (disc < 0.0) { discard; }
-        let t = -b - sqrt(disc);
-        if (t < 0.0) { discard; }
-        let hit = cam_pos + rd * t;
+        let isect = ray_sphere_intersection(cam_pos, rd, sphere_center, sphere_radius);
+        if (!isect.hit) { discard; }
+        let hit = cam_pos + rd * isect.t;
         world_normal = normalize(hit - sphere_center);
         // Reproject hit point to get correct clip-space depth.
         let clip_hit = globals.view_proj * vec4f(hit, 1.0);