vk: fix crashing on maps with skybox

We were using a negative value for `SURF_SKY` surfaces, which hit an
assert on uploading kusochki.

ref/vk/TODO.md

@@ -4,6 +4,13 @@
 - [x] remove stvecs from patches -- not used, inconvenient
 - [x] patch texture coordinates by matrices
 - [x] add `_xvk_tex_rotate`
+- [x] ASSERT in c2a5 -- skybox sentinel
+- [ ] woditschka
+     - [ ] height not switching to negative underwater
+        - not even sure we need it?
+     - [ ] do not draw water sides when not requested.
+     - [ ] potentially collinear planes vs ray tracing #264
+- [ ] update animated textures is now super slow
 
 # 2023-11-06 E325
 - [x] fix material asserts and inherit
@@ -182,7 +189,6 @@
 - [ ] rtx: do not rebuild static studio models (most of them). BLAS building takes most of the frame time (~12ms where ray tracing itself is just 3ms)
 - [ ] rtx: importance-sample sky light; there are sky surfaces that we can consider light sources
 - [ ] cull water surfaces (see c3a2a)
-- [ ] create water surfaces once in vk_brush
 - [ ] consider doing per-geometry rendermode: brushes can be built only once; late transparency depth sorting for vk render;
 - [ ] rtx: too many emissive lights in c3a1b
 - [ ] studio models: pre-compute buffer sizes and allocate them at once
@@ -606,3 +612,6 @@
 - [x] render skybox
 - [x] better flashlight: spotlight instead of dlight point
 - [x] rtx: add fps: rasterize into G-buffer, and only then compute lighting with rtx
+
+# Done somewhen
+- [x] create water surfaces once in vk_brush

ref/vk/shaders/ray_interop.h

@@ -71,7 +71,7 @@ LIST_SPECIALIZATION_CONSTANTS(DECLARE_SPECIALIZATION_CONSTANT)
 #define MATERIAL_MODE_BLEND_GLOW 5
 #define MATERIAL_MODE_COUNT 6
 
-#define TEX_BASE_SKYBOX 0xffffffffu
+#define TEX_BASE_SKYBOX 0x0f000000u
 
 struct Material {
 	uint tex_base_color;

ref/vk/vk_brush.c

@@ -1174,7 +1174,7 @@ static qboolean fillBrushSurfaces(fill_geometries_args_t args) {
 			model_geometry->index_offset = index_offset;
 
 			if ( type == BrushSurface_Sky ) {
-#define TEX_BASE_SKYBOX 0xffffffffu // FIXME ray_interop.h
+#define TEX_BASE_SKYBOX 0x0f000000u // FIXME ray_interop.h
 				model_geometry->material.tex_base_color = TEX_BASE_SKYBOX;
 			} else {
 				ASSERT(!FBitSet( surf->flags, SURF_DRAWTILED ));

ref/vk/vk_materials.c

@@ -161,6 +161,11 @@ static int addMaterial(const char *name, const r_vk_material_t* mat) {
 
 	printMaterial(g_materials.count);
 
+	ASSERT(mat->tex_base_color >= 0);
+	ASSERT(mat->tex_metalness >= 0);
+	ASSERT(mat->tex_roughness >= 0);
+	ASSERT(mat->tex_normalmap >= 0);
+
 	return g_materials.count++;
 }
 

ref/vk/vk_ray_model.c

@@ -30,9 +30,16 @@ static void applyMaterialToKusok(vk_kusok_data_t* kusok, const vk_render_geometr
 	ASSERT(mat);
 
 	ASSERT(mat->tex_base_color >= 0);
+	ASSERT(mat->tex_base_color < MAX_TEXTURES || mat->tex_base_color == TEX_BASE_SKYBOX);
+
 	ASSERT(mat->tex_roughness >= 0);
+	ASSERT(mat->tex_roughness < MAX_TEXTURES);
+
 	ASSERT(mat->tex_metalness >= 0);
+	ASSERT(mat->tex_metalness < MAX_TEXTURES);
+
 	ASSERT(mat->tex_normalmap >= 0);
+	ASSERT(mat->tex_normalmap < MAX_TEXTURES);
 
 	// TODO split kusochki into static geometry data and potentially dynamic material data
 	// This data is static, should never change