From 7632def9d63849e8ee328f3bfed71f7453cb2c99 Mon Sep 17 00:00:00 2001
From: Gary Sweet <gary.sweet@broadcom.com>
Date: Wed, 6 Mar 2019 12:41:13 +0000
Subject: [PATCH] Fix sample count limits in deferredmultisampling

The sample count was previously fixed at 8, which is not supported
on some platforms. The code now checks for the maximum supported
sample count and uses that instead.

If you would prefer the upper limit to be fixed at 8, that is
obviously trivial to change.
---
 data/shaders/deferredmultisampling/debug.frag |   2 +-
 .../deferredmultisampling/debug.frag.spv      | Bin 3268 -> 3232 bytes
 .../deferredmultisampling.cpp                 |  28 ++++++++++++++----
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/data/shaders/deferredmultisampling/debug.frag b/data/shaders/deferredmultisampling/debug.frag
index 872303f8..29aa0008 100644
--- a/data/shaders/deferredmultisampling/debug.frag
+++ b/data/shaders/deferredmultisampling/debug.frag
@@ -8,7 +8,7 @@ layout (location = 0) in vec3 inUV;
 
 layout (location = 0) out vec4 outFragColor;
 
-#define NUM_SAMPLES 8
+layout (constant_id = 0) const int NUM_SAMPLES = 8;
 
 vec4 resolve(sampler2DMS tex, ivec2 uv)
 {
diff --git a/data/shaders/deferredmultisampling/debug.frag.spv b/data/shaders/deferredmultisampling/debug.frag.spv
index b334d148778c1283fbd580b2060d6399866eac5a..03e4c9f4e891b6c047a5237c5aecea3f527baa79 100644
GIT binary patch
delta 101
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v!IO;{KXQP?7=d`R4AT@wMx)6anbkMHU|zt%o6o?)zy_2s24cm@tvvPsa-<T3

delta 148
zcmZ1=c|?+vnMs+Qfq{{MaUy4OIFQA_41`QT`Vb=n0}BHugS$_>V~|sPacV(gQDRAI
zd~rr%N@`Jjeo|Iya!E0&8lY5WUV3~^VqSV_VtQ)4iIG7;VsiGx>f*^vjPEuv^)NDO
ePwr(_7tjV8%?7l@7>I$uaq|}D1ss!8cx(Xme<Z2^

diff --git a/examples/deferredmultisampling/deferredmultisampling.cpp b/examples/deferredmultisampling/deferredmultisampling.cpp
index 24aa1cf6..994a64b3 100644
--- a/examples/deferredmultisampling/deferredmultisampling.cpp
+++ b/examples/deferredmultisampling/deferredmultisampling.cpp
@@ -25,8 +25,6 @@
 
 #define VERTEX_BUFFER_BIND_ID 0
 #define ENABLE_VALIDATION false
-// todo: check if hardware supports sample number (or select max. supported)
-#define SAMPLE_COUNT VK_SAMPLE_COUNT_8_BIT
 
 class VulkanExample : public VulkanExampleBase
 {
@@ -34,6 +32,7 @@ public:
 	bool debugDisplay = false;
 	bool useMSAA = true;
 	bool useSampleShading = true;
+	VkSampleCountFlagBits sampleCount = VK_SAMPLE_COUNT_1_BIT;
 
 	struct {
 		struct {
@@ -267,7 +266,7 @@ public:
 		image.extent.depth = 1;
 		image.mipLevels = 1;
 		image.arrayLayers = 1;
-		image.samples = SAMPLE_COUNT;
+		image.samples = sampleCount;
 		image.tiling = VK_IMAGE_TILING_OPTIMAL;
 		image.usage = usage | VK_IMAGE_USAGE_SAMPLED_BIT;
 
@@ -345,7 +344,7 @@ public:
 		// Init attachment properties
 		for (uint32_t i = 0; i < 4; ++i)
 		{
-			attachmentDescs[i].samples = SAMPLE_COUNT;
+			attachmentDescs[i].samples = sampleCount;
 			attachmentDescs[i].loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
 			attachmentDescs[i].storeOp = VK_ATTACHMENT_STORE_OP_STORE;
 			attachmentDescs[i].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
@@ -441,6 +440,7 @@ public:
 		sampler.mipLodBias = 0.0f;
 		sampler.maxAnisotropy = 1.0f;
 		sampler.minLod = 0.0f;
+		sampler.minLod = 0.0f;
 		sampler.maxLod = 1.0f;
 		sampler.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
 		VK_CHECK_RESULT(vkCreateSampler(device, &sampler, nullptr, &colorSampler));
@@ -925,7 +925,7 @@ public:
 		specializationEntry.offset = 0;
 		specializationEntry.size = sizeof(uint32_t);
 		
-		uint32_t specializationData = SAMPLE_COUNT;
+		uint32_t specializationData = sampleCount;
 
 		VkSpecializationInfo specializationInfo;
 		specializationInfo.mapEntryCount = 1;
@@ -944,8 +944,10 @@ public:
 		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipelines.deferredNoMSAA));
 
 		// Debug display pipeline
+		specializationData = sampleCount;
 		shaderStages[0] = loadShader(getAssetPath() + "shaders/deferredmultisampling/debug.vert.spv", VK_SHADER_STAGE_VERTEX_BIT);
 		shaderStages[1] = loadShader(getAssetPath() + "shaders/deferredmultisampling/debug.frag.spv", VK_SHADER_STAGE_FRAGMENT_BIT);
+		shaderStages[1].pSpecializationInfo = &specializationInfo;
 		VK_CHECK_RESULT(vkCreateGraphicsPipelines(device, pipelineCache, 1, &pipelineCreateInfo, nullptr, &pipelines.debug));
 		
 		// Offscreen scene rendering pipeline
@@ -956,7 +958,7 @@ public:
 
 		//rasterizationState.polygonMode = VK_POLYGON_MODE_LINE;
 		//rasterizationState.lineWidth = 2.0f;
-		multisampleState.rasterizationSamples = SAMPLE_COUNT;
+		multisampleState.rasterizationSamples = sampleCount;
 		multisampleState.alphaToCoverageEnable = VK_TRUE;
 
 		// Separate render pass
@@ -1129,6 +1131,7 @@ public:
 	void prepare()
 	{
 		VulkanExampleBase::prepare();
+		sampleCount = getMaxUsableSampleCount();
 		loadAssets();
 		setupVertexDescriptions();
 		prepareOffscreenFramebuffer();
@@ -1173,6 +1176,19 @@ public:
 			}
 		}
 	}
+
+	// Returns the maximum sample count usable by the platform
+	VkSampleCountFlagBits getMaxUsableSampleCount()
+	{
+		VkSampleCountFlags counts = std::min(deviceProperties.limits.framebufferColorSampleCounts, deviceProperties.limits.framebufferDepthSampleCounts);
+		if (counts & VK_SAMPLE_COUNT_64_BIT) { return VK_SAMPLE_COUNT_64_BIT; }
+		if (counts & VK_SAMPLE_COUNT_32_BIT) { return VK_SAMPLE_COUNT_32_BIT; }
+		if (counts & VK_SAMPLE_COUNT_16_BIT) { return VK_SAMPLE_COUNT_16_BIT; }
+		if (counts & VK_SAMPLE_COUNT_8_BIT) { return VK_SAMPLE_COUNT_8_BIT; }
+		if (counts & VK_SAMPLE_COUNT_4_BIT) { return VK_SAMPLE_COUNT_4_BIT; }
+		if (counts & VK_SAMPLE_COUNT_2_BIT) { return VK_SAMPLE_COUNT_2_BIT; }
+		return VK_SAMPLE_COUNT_1_BIT;
+	}
 };
 
 VULKAN_EXAMPLE_MAIN()