diff --git a/ref/vk/shaders/ray_interop.h b/ref/vk/shaders/ray_interop.h
index cda6263845..c6ad0bb516 100644
--- a/ref/vk/shaders/ray_interop.h
+++ b/ref/vk/shaders/ray_interop.h
@@ -89,6 +89,7 @@ struct Kusok {
 	float normal_scale;
 	uint flags;
 
+	// TODO per-model
 	mat4 prev_transform;
 };
 
diff --git a/ref/vk/vk_brush.c b/ref/vk/vk_brush.c
index 082a667f33..b320c90215 100644
--- a/ref/vk/vk_brush.c
+++ b/ref/vk/vk_brush.c
@@ -238,7 +238,7 @@ static void EmitWaterPolys( const cl_entity_t *ent, const msurface_t *warp, qboo
 		const vk_render_geometry_t geometry = {
 			.texture = warp->texinfo->texture->gl_texturenum, // FIXME assert >= 0
 			.material = kXVkMaterialWater,
-			.surf = warp,
+			.surf_deprecate = warp,
 
 			.max_vertex = num_vertices,
 			.vertex_offset = buffer.vertices.unit_offset,
@@ -407,7 +407,7 @@ void VK_BrushModelDraw( const cl_entity_t *ent, int render_mode, float blend, co
 
 	for (int i = 0; i < bmodel->render_model.num_geometries; ++i) {
 		vk_render_geometry_t *geom = bmodel->render_model.geometries + i;
-		const int surface_index = geom->surf - mod->surfaces;
+		const int surface_index = geom->surf_deprecate - mod->surfaces;
 		const xvk_patch_surface_t *const patch_surface = R_VkPatchGetSurface(surface_index);
 
 		if (render_mode == kRenderTransColor) {
@@ -419,7 +419,7 @@ void VK_BrushModelDraw( const cl_entity_t *ent, int render_mode, float blend, co
 		} else {
 			// Optionally patch by texture_s pointer and run animations
 			const struct texture_s *texture_override = patch_surface ? patch_surface->tex : NULL;
-			const texture_t *t = R_TextureAnimation(ent, geom->surf, texture_override);
+			const texture_t *t = R_TextureAnimation(ent, geom->surf_deprecate, texture_override);
 			if (t->gl_texturenum >= 0)
 				geom->texture = t->gl_texturenum;
 		}
@@ -561,7 +561,7 @@ static qboolean loadBrushSurfaces( model_sizes_t sizes, const model_t *mod ) {
 
 			VectorClear(model_geometry->emissive);
 
-			model_geometry->surf = surf;
+			model_geometry->surf_deprecate = surf;
 			model_geometry->texture = tex_id;
 
 			model_geometry->vertex_offset = buffer.vertices.unit_offset;
diff --git a/ref/vk/vk_render.h b/ref/vk/vk_render.h
index 8bd1f2be96..b61e32b003 100644
--- a/ref/vk/vk_render.h
+++ b/ref/vk/vk_render.h
@@ -27,33 +27,56 @@ void VK_RenderStateSetMatrixModel(const matrix4x4 model);
 // FIXME these should be bits, not enums
 typedef enum {
 	kXVkMaterialRegular = 0,
+
+	// Set for dynamic water surface in vk_brush.c. Used to
+	// TYno NOT USED, REMOVE NOW.
+	// Remove: No prerequisites. Water material should be decided based on texture, not whether it's being drawn as dynamic water surface.
 	kXVkMaterialWater,
+
+	// Set for SURF_DRAWSKY surfaces in vk_brush.c.
+	// Used: for setting KUSOK_MATERIAL_FLAG_SKYBOX for skybox texture sampling and environment shadows.
+	// Remove: pass it as a special texture/material index (e.g. -2).
 	kXVkMaterialSky,
+
+	// Set by beams and sprites.
+	// Used: as a negative flag for setting model color from emissive color. A bit tricky, don't really follow.
+	// Remove: ???
 	kXVkMaterialEmissive,
+
+	// Set by sprites.
+	// Used: glow means no depth test. Allows for slight ray overshoot (KUSOK_MATERIAL_FLAG_FIXME_GLOW). Desired effect: literally glow.
+	// Remove: should be able to extract this info from kRenderType
 	kXVkMaterialEmissiveGlow,
+
+	// Set for brush surfaces with dynamic UVs.
+	// Used: currently unused, conveyors are drawn incorrectly.
+	// Remove: it's more efficient to solve this via explicit list of dynamic-uv geometries.
 	kXVkMaterialConveyor,
+
+	// Set for chrome studio submodels.
+	// Used: ray tracing sets gray roughness texture to get smooth surface look.
+	// Remove: Have an explicit material for chrome surfaces.
 	kXVkMaterialChrome,
 } XVkMaterialType;
 
 typedef struct vk_render_geometry_s {
 	int index_offset, vertex_offset;
 
-	// Animated textures will be dynamic and change between frames
-	int texture;
-
-	// If this geometry is special, it will have a material type override
-	XVkMaterialType material;
-
 	uint32_t element_count;
 
 	// Maximum index of vertex used for this geometry; needed for ray tracing BLAS building
 	uint32_t max_vertex;
 
 	// Non-null only for brush models
-	// Used for:
-	// - updating animated textures for brush models
-	// - updating dynamic lights (TODO: can decouple from surface/brush models by providing texture_id and aabb directly here)
-	const struct msurface_s *surf;
+	// Used for updating animated textures for brush models
+	// Remove: have an explicit list of surfaces with animated textures
+	const struct msurface_s *surf_deprecate;
+
+	// Animated textures will be dynamic and change between frames
+	int texture;
+
+	// If this geometry is special, it will have a material type override
+	XVkMaterialType material;
 
 	// for kXVkMaterialEmissive{,Glow} and others
 	vec3_t emissive;
@@ -61,12 +84,45 @@ typedef struct vk_render_geometry_s {
 
 typedef enum {
 	kVkRenderTypeSolid,     // no blending, depth RW
+
+	// Mix alpha blending with depth test and write
+	// Set by:
+	// - brush:  kRenderTransColor
+	// - studio: kRenderTransColor, kRenderTransTexture, kRenderTransAlpha, kRenderGlow
+	// - sprite: kRenderTransColor, kRenderTransTexture
+	// - triapi: kRenderTransColor, kRenderTransTexture
 	kVkRenderType_A_1mA_RW, // blend: src*a + dst*(1-a), depth: RW
+
+	// Mix alpha blending with depth test only
+	// Set by:
+	// - brush:  kRenderTransTexture, kRenderGlow
+	// - sprite: kRenderTransAlpha
+	// - triapi: kRenderTransAlpha
 	kVkRenderType_A_1mA_R,  // blend: src*a + dst*(1-a), depth test
+
+	// Additive alpha blending, no depth
+	// Set by:
+	// - sprite: kRenderGlow
 	kVkRenderType_A_1,      // blend: src*a + dst, no depth test or write
+
+	// Additive alpha blending with depth test
+	// Set by:
+	// - brush: kRenderTransAdd
+	// - beams: all modes except kRenderNormal and beams going through triapi
+	// - sprite: kRenderTransAdd
+	// - triapi: kRenderTransAdd, kRenderGlow
 	kVkRenderType_A_1_R,    // blend: src*a + dst, depth test
+
+	// No blend, alpha test, depth test and write
+	// Set by:
+	// - brush: kRenderTransAlpha
 	kVkRenderType_AT,       // no blend, depth RW, alpha test
+
+	// Additive no alpha blend, depth test only
+	// Set by:
+	// - studio: kRenderTransAdd
 	kVkRenderType_1_1_R,    // blend: src + dst, depth test
+
 	kVkRenderType_COUNT
 } vk_render_type_e;
 
diff --git a/ref/vk/vk_triapi.c b/ref/vk/vk_triapi.c
index 152ffbc241..2b95239e97 100644
--- a/ref/vk/vk_triapi.c
+++ b/ref/vk/vk_triapi.c
@@ -42,13 +42,21 @@ int TriSpriteTexture( model_t *pSpriteModel, int frame )
 void TriRenderMode( int render_mode ) {
 	switch( render_mode )
 	{
-	case kRenderTransAlpha: g_triapi.render_type = kVkRenderType_A_1mA_R; break;
+	case kRenderTransAlpha:
+		g_triapi.render_type = kVkRenderType_A_1mA_R;
+		break;
 	case kRenderTransColor:
-	case kRenderTransTexture: g_triapi.render_type = kVkRenderType_A_1mA_RW; break;
+	case kRenderTransTexture:
+		g_triapi.render_type = kVkRenderType_A_1mA_RW;
+		break;
 	case kRenderGlow:
-	case kRenderTransAdd: g_triapi.render_type = kVkRenderType_A_1_R; break;
+	case kRenderTransAdd:
+		g_triapi.render_type = kVkRenderType_A_1_R;
+		break;
 	case kRenderNormal:
-	default: g_triapi.render_type = kVkRenderTypeSolid; break;
+	default:
+		g_triapi.render_type = kVkRenderTypeSolid;
+		break;
 	}
 }