Chams: fix the flat viewmodel, glow outline and fullbright styles

- Flat uses the solid model shader with the FLAT flag on the viewmodel;
  vgui/white does not draw skinned models and made the hands vanish.
- Glow outline draws its wireframe contour with ZNEARER and a brightened
  colour, so the solid base no longer hides the contour.
- Fullbright is now additive + self-illuminated with the colour lifted toward
  white, so it reads differently from Solid and Additive glow.

2 files changed, 39 insertions, 15 deletions

diff --git a/CONTEXT.md b/CONTEXT.md
index be526fc..f7fdecb 100644
--- a/CONTEXT.md
+++ b/CONTEXT.md
@@ -296,12 +296,16 @@ vocabulary / decisions.
   (IMaterialVar slot 11, SetVecValue 3-float slot 11) and `ColorModulate`
   (slot 28). Shared materials are restored after each draw.
 - Styles are built from the resident materials and material flags:
-  0 Flat (`vgui/white` with FLAT), 1 Wireframe (`debug/debugwireframe`),
-  2 Additive (`debug/debugtranslucentsinglecolor` + ADDITIVE), 3 Solid,
-  4 White (solid, colour forced white), 5 Fullbright (solid + FLAT|SELFILLUM),
-  6 Glow outline (solid plus a `debug/debugwireframe` contour pass).
-  `models/debug/debugwhite` is EP2-only and the old VGUI additive material is
-  invisible on NPCs; the styles no longer depend on them.
+  0 Flat (`vgui/white` with FLAT on NPCs; the solid model shader with FLAT on
+  the viewmodel, because VGUI materials do not draw skinned models),
+  1 Wireframe (`debug/debugwireframe`), 2 Additive
+  (`debug/debugtranslucentsinglecolor` + ADDITIVE), 3 Solid, 4 White (solid,
+  colour forced white), 5 Fullbright (solid + ADDITIVE|SELFILLUM with the
+  colour lifted toward white), 6 Glow outline (solid plus a
+  `debug/debugwireframe` contour pass drawn with ZNEARER (1 << 10) and a
+  brightened colour so the base cannot bury it). `models/debug/debugwhite` is
+  EP2-only and the old VGUI additive material is invisible on NPCs; the styles
+  no longer depend on them.
 - Style materials are preloaded from `outer_draw` (throttled) and cached; the
   render hook never calls FindMaterial itself. A missing style uses solid.
 - Feature is off by default. Config sections: `[chams]` (active/bind),
diff --git a/src/studio.cpp b/src/studio.cpp
index 803b6b2..301e781 100644
--- a/src/studio.cpp
+++ b/src/studio.cpp
@@ -249,25 +249,28 @@ void chams_color(void *mat, float r, float g, float b) {
 }
 
 void chams_apply(void *mat, bool ignorez, int style, bool force_white,
-                 const int *rgb) {
+                 const int *rgb, bool znearer) {
   using FlagFn = void (*)(void *, int, bool);
   float r = force_white ? 1.0f : (float)rgb[0] / 255.0f;
   float g = force_white ? 1.0f : (float)rgb[1] / 255.0f;
   float b = force_white ? 1.0f : (float)rgb[2] / 255.0f;
   chams_color(mat, r, g, b);
-  // 0 Flat, 1 Wireframe, 2 Additive, 3 Solid, 4 White, 5 Fullbright,
-  // 6 Glow outline (solid base; the wireframe overlay is a second draw).
+  // 0 Flat, 1 Wireframe, 2 Additive, 3 Solid, 4 White, 5 Fullbright
+  // (additive white glow), 6 Glow outline (solid base; the wireframe overlay
+  // is a second draw with ZNEARER so its contour is not hidden by the base).
   vfunc<FlagFn>(mat, 29)(mat, 1 << 15 /* IGNOREZ */, ignorez);
+  vfunc<FlagFn>(mat, 29)(mat, 1 << 10 /* ZNEARER */, znearer);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 28 /* WIREFRAME */, style == 1);
-  vfunc<FlagFn>(mat, 29)(mat, 1 << 7 /* ADDITIVE */, style == 2);
-  vfunc<FlagFn>(mat, 29)(mat, 1 << 12 /* FLAT */,
-                         style == 0 || style == 5);
+  vfunc<FlagFn>(mat, 29)(mat, 1 << 7 /* ADDITIVE */,
+                         style == 2 || style == 5);
+  vfunc<FlagFn>(mat, 29)(mat, 1 << 12 /* FLAT */, style == 0);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 6 /* SELFILLUM */, style == 5);
 }
 
 void chams_reset(void *mat) {
   using FlagFn = void (*)(void *, int, bool);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 15, false);
+  vfunc<FlagFn>(mat, 29)(mat, 1 << 10, false);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 28, false);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 7, false);
   vfunc<FlagFn>(mat, 29)(mat, 1 << 12, false);
@@ -297,17 +300,34 @@ void hkdModelExecute(void *self, const void *state, const void *info,
           if (style < 0) style = 0;
           if (style > 6) style = 6;
           void *mat = style_material(style);
+          // vgui/white (Flat) does not draw skinned models, so the viewmodel
+          // uses the solid model shader with the same FLAT flag.
+          if (is_vm && style == 0)
+            mat = viewmodel_material();
           if (!mat)
             return false;
           bool white = style == 4;
-          chams_apply(mat, ignorez, style, white, rgb);
+          // Fullbright is an additive, self-illuminated version of the
+          // chosen colour: lift it toward white so it reads brighter than
+          // the plain additive style.
+          int brgb[3];
+          const int *use_rgb = rgb;
+          if (style == 5) {
+            for (int i = 0; i < 3; i++)
+              brgb[i] = rgb[i] + (255 - rgb[i]) / 2;
+            use_rgb = brgb;
+          }
+          chams_apply(mat, ignorez, style, white, use_rgb, false);
           g_force_override(self, mat, 0 /* OVERRIDE_NORMAL */);
           g_orig_model_exec(self, state, info, bone);
           if (style == 6) {
-            // Solid base plus a wireframe contour pass for depth.
+            // Solid base plus a wireframe contour pass for depth. Brighten
+            // the contour and bias it forward so the base cannot bury it.
             void *wire = g_style_mats[1];
             if (wire && wire != mat) {
-              chams_apply(wire, ignorez, 1, false, rgb);
+              int wrgb[3] = {(rgb[0] + 255) / 2, (rgb[1] + 255) / 2,
+                             (rgb[2] + 255) / 2};
+              chams_apply(wire, ignorez, 1, false, wrgb, true);
               g_force_override(self, wire, 0);
               g_orig_model_exec(self, state, info, bone);
               chams_reset(wire);