[vulkan] Remove elements_t type

This was one of the biggest reasons I had trouble understanding the bsp
display list code, but it turns out it was for dealing with GLES's
16-bit limit on vertex indices. Since vulkan uses 32-bit indices,
there's no need for the extra layer of indirection. I'm pretty sure it
was that lack of understanding that prevented me from removing it when I
first converted the glsl bsp code to vulkan (ie, that 16-bit indices
were the only reason for elements_t).

It's hard to tell whether the change makes much difference to
performance, though it seems it might (noisy stats even over 50 timedemo
loops) and the better data localization indicate it should at least be
just as good if not better. However, the reason for the change is
simplifying the data structures so I can make bsp rendering thread-safe
in preparation for rendering shadow maps.

include/QF/Vulkan/qf_bsp.h

@@ -54,17 +54,11 @@ typedef struct bspvert_s {
 	quat_t      tlst;
 } bspvert_t;
 
-typedef struct elements_s {
-	struct elements_s *_next;
-	struct elements_s *next;
-	uint32_t    first_index;
-	uint32_t    index_count;
-} elements_t;
-
 typedef struct elechain_s {
 	struct elechain_s *_next;
 	struct elechain_s *next;
-	elements_t *elements;
+	uint32_t    first_index;
+	uint32_t    index_count;
 	vec_t      *transform;
 	float      *color;
 } elechain_t;
@@ -120,9 +114,6 @@ typedef struct bspctx_s {
 	elechain_t  *elechains;
 	elechain_t **elechains_tail;
 	elechain_t  *free_elechains;
-	elements_t  *elementss;
-	elements_t **elementss_tail;
-	elements_t  *free_elementss;
 	instsurf_t  *instsurfs;
 	instsurf_t **instsurfs_tail;
 	instsurf_t  *free_instsurfs;

libs/video/renderer/vulkan/vulkan_bsp.c

@@ -162,7 +162,6 @@ release_##name##s (bspctx_t *bctx)									\
 }
 
 GET_RELEASE (elechain_t, elechain)
-GET_RELEASE (elements_t, elements)
 GET_RELEASE (instsurf_t, static_instsurf)
 GET_RELEASE (instsurf_t, instsurf)
 
@@ -216,7 +215,6 @@ clear_texture_chains (bspctx_t *bctx)
 	}
 	clear_tex_chain (r_notexture_mip->render);
 	release_elechains (bctx);
-	release_elementss (bctx);
 	release_instsurfs (bctx);
 }
 
@@ -225,7 +223,6 @@ Vulkan_ClearElements (vulkan_ctx_t *ctx)
 {
 	bspctx_t   *bctx = ctx->bsp_context;
 	release_elechains (bctx);
-	release_elementss (bctx);
 }
 
 static inline void
@@ -307,7 +304,8 @@ add_elechain (vulktex_t *tex, bspctx_t *bctx)
 	elechain_t *ec;
 
 	ec = get_elechain (bctx);
-	ec->elements = get_elements (bctx);
+	ec->first_index = 0;
+	ec->index_count = 0;
 	ec->transform = 0;
 	ec->color = 0;
 	*tex->elechain_tail = ec;
@@ -793,7 +791,6 @@ draw_elechain (elechain_t *ec, VkPipelineLayout layout, qfv_device_t *device,
 			   VkCommandBuffer cmd)
 {
 	qfv_devfuncs_t *dfunc = device->funcs;
-	elements_t *el;
 
 	if (ec->transform) {
 		push_transform (ec->transform, layout, device, cmd);
@@ -801,10 +798,8 @@ draw_elechain (elechain_t *ec, VkPipelineLayout layout, qfv_device_t *device,
 		//FIXME should cache current transform
 		push_transform (identity, layout, device, cmd);
 	}
-	for (el = ec->elements; el; el = el->next) {
+	if (ec->index_count) {
-		if (!el->index_count)
+		dfunc->vkCmdDrawIndexed (cmd, ec->index_count, 1, ec->first_index,
-			continue;
-		dfunc->vkCmdDrawIndexed (cmd, el->index_count, 1, el->first_index,
 								 0, 0);
 	}
 }
@@ -812,13 +807,10 @@ draw_elechain (elechain_t *ec, VkPipelineLayout layout, qfv_device_t *device,
 static void
 reset_elechain (elechain_t *ec)
 {
-	elements_t *el;
+	ec->first_index = 0;
+	ec->index_count = 0;
+}
 
-	for (el = ec->elements; el; el = el->next) {
-		el->first_index = 0;
-		el->index_count = 0;
-	}
-}
 
 static void
 bsp_begin_subpass (QFV_BspSubpass subpass, VkPipeline pipeline,
@@ -975,8 +967,7 @@ sky_end (vulkan_ctx_t *ctx)
 }
 
 static inline void
-add_surf_elements (vulktex_t *tex, instsurf_t *is,
+add_surf_elements (vulktex_t *tex, instsurf_t *is, elechain_t **ec,
-				   elechain_t **ec, elements_t **el,
 				   bspctx_t *bctx, bspframe_t *bframe)
 {
 	bsppoly_t  *poly = (bsppoly_t *) is->surface->polys;
@@ -985,19 +976,17 @@ add_surf_elements (vulktex_t *tex, instsurf_t *is,
 		(*ec) = add_elechain (tex, bctx);
 		(*ec)->transform = is->transform;
 		(*ec)->color = is->color;
-		(*el) = (*ec)->elements;
+		(*ec)->first_index = bframe->index_count;
-		(*el)->first_index = bframe->index_count;
 	}
 	if (is->transform != (*ec)->transform || is->color != (*ec)->color) {
 		(*ec) = add_elechain (tex, bctx);
 		(*ec)->transform = is->transform;
 		(*ec)->color = is->color;
-		(*el) = (*ec)->elements;
+		(*ec)->first_index = bframe->index_count;
-		(*el)->first_index = bframe->index_count;
 	}
 	memcpy (bframe->index_data + bframe->index_count,
 			poly->indices, poly->count * sizeof (poly->indices[0]));
-	(*el)->index_count += poly->count;
+	(*ec)->index_count += poly->count;
 	bframe->index_count += poly->count;
 }
 
@@ -1006,12 +995,11 @@ build_tex_elechain (vulktex_t *tex, bspctx_t *bctx, bspframe_t *bframe)
 {
 	instsurf_t *is;
 	elechain_t *ec = 0;
-	elements_t *el = 0;
 
 	for (is = tex->tex_chain; is; is = is->tex_chain) {
 		// emit the polygon indices for the surface to the texture's
 		// element chain
-		add_surf_elements (tex, is, &ec, &el, bctx, bframe);
+		add_surf_elements (tex, is, &ec, bctx, bframe);
 	}
 }
 
@@ -1117,7 +1105,6 @@ Vulkan_DrawWaterSurfaces (qfv_renderframe_t *rFrame)
 	instsurf_t *is;
 	vulktex_t  *tex = 0;
 	elechain_t *ec = 0;
-	elements_t *el = 0;
 
 	if (!bctx->waterchain)
 		return;
@@ -1146,7 +1133,7 @@ Vulkan_DrawWaterSurfaces (qfv_renderframe_t *rFrame)
 		}
 		// emit the polygon indices for the surface to the texture's
 		// element chain
-		add_surf_elements (tex, is, &ec, &el, bctx, bframe);
+		add_surf_elements (tex, is, &ec, bctx, bframe);
 	}
 	if (tex) {
 		bind_texture (tex, 1, bctx->layout, dfunc,
@@ -1176,7 +1163,6 @@ Vulkan_DrawSky (qfv_renderframe_t *rFrame)
 	instsurf_t *is;
 	vulktex_t  *tex = 0;
 	elechain_t *ec = 0;
-	elements_t *el = 0;
 
 	if (!bctx->sky_chain)
 		return;
@@ -1208,7 +1194,7 @@ Vulkan_DrawSky (qfv_renderframe_t *rFrame)
 		}
 		// emit the polygon indices for the surface to the texture's
 		// element chain
-		add_surf_elements (tex, is, &ec, &el, bctx, bframe);
+		add_surf_elements (tex, is, &ec, bctx, bframe);
 	}
 	if (tex) {
 		bind_texture (tex, 1, bctx->layout, dfunc,
@@ -1350,7 +1336,6 @@ Vulkan_Bsp_Init (vulkan_ctx_t *ctx)
 	bctx->sky_chain_tail = &bctx->sky_chain;
 	bctx->static_instsurfs_tail = &bctx->static_instsurfs;
 	bctx->elechains_tail = &bctx->elechains;
-	bctx->elementss_tail = &bctx->elementss;
 	bctx->instsurfs_tail = &bctx->instsurfs;
 
 	bctx->light_scrap = QFV_CreateScrap (device, "lightmap_atlas", 2048,