Ray-caster: pass colors in through uniforms

app-proto/inversive-display/src/inversive.frag

@@ -28,6 +28,7 @@ vecInv sphere(vec3 center, float radius) {
 const int SPHERE_MAX = 12;
 uniform int sphere_cnt;
 uniform vecInv sphere_list[SPHERE_MAX];
+uniform vec3 color_list[SPHERE_MAX];
 
 // view
 uniform vec2 resolution;
@@ -135,6 +136,7 @@ void main() {
     
     // initialize two spheres
     vecInv sphere_list_internal [SPHERE_MAX];
+    vec3 color_list_internal [SPHERE_MAX];
     if (use_test_construction) {
         /* DEBUG */
         // spheres 0 and 1 are identical in the test construction hard-coded
@@ -144,15 +146,15 @@ void main() {
         sphere_list_internal[0] = sphere(vec3(0.5, 0.5, -5. + ctrl.x), radius.x);
         sphere_list_internal[1] = sphere(vec3(-0.5, -0.5, -5. + ctrl.y), radius.y);
         sphere_list_internal[2] = sphere(vec3(-0.5, 0.5, -5.), 0.5);
+        color_list_internal[0] = vec3(1., 0.25, 0.);
+        color_list_internal[1] = vec3(0., 0.25, 1.);
+        color_list_internal[2] = vec3(0.25, 0., 1.0);
     } else {
         for (int i = 0; i < sphere_cnt; ++i) {
             sphere_list_internal[i] = sphere_list[i];
+            color_list_internal[i] = color_list[i];
         }
     }
-    vec3 color_list [SPHERE_MAX];
-    color_list[0] = vec3(1., 0.25, 0.);
-    color_list[1] = vec3(0., 0.25, 1.);
-    color_list[2] = vec3(0.25, 0., 1.0);
     
     // cast rays through the spheres
     vec2 depth_pairs [SPHERE_MAX];
@@ -161,11 +163,11 @@ void main() {
     for (int i = 0; i < sphere_cnt; ++i) {
         vec2 hit_depths = sphere_cast(sphere_list_internal[i], dir);
         if (!isnan(hit_depths[0])) {
-            frags[frag_cnt] = sphere_shading(sphere_list_internal[i], hit_depths[0] * dir, color_list[i], i);
+            frags[frag_cnt] = sphere_shading(sphere_list_internal[i], hit_depths[0] * dir, color_list_internal[i], i);
             ++frag_cnt;
         }
         if (!isnan(hit_depths[1])) {
-            frags[frag_cnt] = sphere_shading(sphere_list_internal[i], hit_depths[1] * dir, color_list[i], i);
+            frags[frag_cnt] = sphere_shading(sphere_list_internal[i], hit_depths[1] * dir, color_list_internal[i], i);
             ++frag_cnt;
         }
     }

app-proto/inversive-display/src/main.rs

@@ -30,10 +30,13 @@ fn get_uniform_array_locations<const N: usize>(
     context: &WebGl2RenderingContext,
     program: &WebGlProgram,
     var_name: &str,
-    member_name: &str
+    member_name_opt: Option<&str>
 ) -> [Option<WebGlUniformLocation>; N] {
     array::from_fn(|n| {
-        let name = format!("{var_name}[{n}].{member_name}");
+        let name = match member_name_opt {
+            Some(member_name) => format!("{var_name}[{n}].{member_name}"),
+            None => format!("{var_name}[{n}]")
+        };
         context.get_uniform_location(&program, name.as_str())
     })
 }
@@ -103,6 +106,11 @@ fn main() {
             // list construction elements
             const SPHERE_MAX: usize = 12;
             let mut sphere_vec = Vec::<DVector<f64>>::new();
+            let color_vec = vec![
+                [1.00_f32, 0.25_f32, 0.00_f32],
+                [0.00_f32, 0.25_f32, 1.00_f32],
+                [0.25_f32, 0.00_f32, 1.00_f32]
+            ];
             
             // get the display canvas
             let canvas = display
@@ -163,10 +171,13 @@ fn main() {
             let position_index = ctx.get_attrib_location(&program, "position") as u32;
             let sphere_cnt_loc = ctx.get_uniform_location(&program, "sphere_cnt");
             let sphere_sp_locs = get_uniform_array_locations::<SPHERE_MAX>(
-                &ctx, &program, "sphere_list", "sp"
+                &ctx, &program, "sphere_list", Some("sp")
             );
             let sphere_lt_locs = get_uniform_array_locations::<SPHERE_MAX>(
-                &ctx, &program, "sphere_list", "lt"
+                &ctx, &program, "sphere_list", Some("lt")
+            );
+            let color_locs = get_uniform_array_locations::<SPHERE_MAX>(
+                &ctx, &program, "color_list", None
             );
             let resolution_loc = ctx.get_uniform_location(&program, "resolution");
             let shortdim_loc = ctx.get_uniform_location(&program, "shortdim");
@@ -221,6 +232,10 @@ fn main() {
                         sphere_lt_locs[n].as_ref(),
                         v[3] as f32, v[4] as f32
                     );
+                    ctx.uniform3fv_with_f32_array(
+                        color_locs[n].as_ref(),
+                        &color_vec[n]
+                    );
                 }
                 
                 // pass the control parameters