[vulkan] Make lighting samplers configurable

My VersaPro doesn't support more than 32 per-stage samplers (lavapipe).
This is a small part of getting Vulkan to run on lavapipe and even in
itself is rather incomplete.

libs/video/renderer/vulkan/qfpipeline.plist

@@ -1,4 +1,10 @@
 {
+	limits = {
+		//FIXME this really needs to be an external variable as the C code
+		//needs to agree on the size, so it might as well set maxSamplers
+		//directly (and any other such variable)
+		maxSamplers = "min (256u, $physDevLimits.maxPerStageDescriptorSamplers)";
+	};
 	samplers = {
 		quakepic = {
 			magFilter = nearest;
@@ -120,7 +126,7 @@
 			bindings = (
 				{
 					type = combined_image_sampler;
-					descriptorCount = "$frames.size * 256z";
+					descriptorCount = "$frames.size * size_t($properties.limits.maxSamplers)";
 				},
 			);
 		};
@@ -308,7 +314,7 @@
 				{
 					binding = 0;
 					descriptorType = combined_image_sampler;
-					descriptorCount = 256;
+					descriptorCount = $properties.limits.maxSamplers;
 					stageFlags = fragment;
 				},
 			);
@@ -903,6 +909,12 @@
 					stage = fragment;
 					name = main;
 					module = $builtin/lighting.frag;
+					specializationInfo = {
+						mapEntries = (
+							{ size = 4; offset = 0; constantID = 0; },
+						);
+						data = "array($properties.limits.maxSamplers)";
+					};
 				},
 			);
 			vertexInput   = $properties.fsquad.vertexInput;

libs/video/renderer/vulkan/shader/lighting.frag

@@ -14,8 +14,6 @@ struct LightData {
 	vec3        direction;
 	float       cone;
 };
-//XXX can't include :( be sure to keep up to date with qf_lighting.h
-#define MaxLights   256
 
 #define StyleMask   0x07f
 #define ModelMask   0x380
@@ -33,6 +31,8 @@ struct LightData {
 #define ST_CASCADE  (2 << 10)	// cascaded shadow maps
 #define ST_CUBE     (3 << 10)	// cubemap (omni, large spotlight)
 
+layout (constant_id = 0) const int MaxLights = 256;
+
 layout (set = 2, binding = 0) uniform sampler2DArrayShadow shadowCascade[MaxLights];
 layout (set = 2, binding = 0) uniform sampler2DShadow shadowPlane[MaxLights];
 layout (set = 2, binding = 0) uniform samplerCubeShadow shadowCube[MaxLights];

libs/video/renderer/vulkan/vulkan_lighting.c

@@ -416,7 +416,9 @@ Vulkan_Lighting_Init (vulkan_ctx_t *ctx)
 		lframe->shadowWrite = base_image_write;
 		lframe->shadowWrite.dstSet = shadow_set->a[i];
 		lframe->shadowWrite.dstBinding = 0;
-		lframe->shadowWrite.descriptorCount = MaxLights;
+		lframe->shadowWrite.descriptorCount
+			= min (MaxLights,
+			device->physDev->properties.limits.maxPerStageDescriptorSamplers);
 		lframe->shadowWrite.pImageInfo = lframe->shadowInfo;
 	}
 	free (attach_set);