Add descriptors

main.cpp

@@ -135,6 +135,9 @@ wapp_intern VkCommandPool command_pool                   = VK_NULL_HANDLE;
 wapp_intern VkCommandBufferArray command_buffers;
 wapp_intern TextureArray textures;
 wapp_intern VkDescriptorImageInfoArray tex_descriptors;
+wapp_intern VkDescriptorSetLayout desc_set_layout_tex    = VK_NULL_HANDLE;
+wapp_intern VkDescriptorPool desc_pool                   = VK_NULL_HANDLE;
+wapp_intern VkDescriptorSet desc_set_tex                 = VK_NULL_HANDLE;
 // }}}
 
 int main() {
@@ -807,6 +810,92 @@ int main() {
 		ktxTexture_Destroy(texture);
 		// }}}
 	}
+
+	// {{{ Descriptor Indexing
+	// A descriptor is a handle that describes a shader resource.
+	//
+	// Descriptors are added into Descriptor Sets which are allocated from a Descriptor Pool.
+	// A descriptor set object is an opaque object containing storage for a set of descriptors,
+	// where the types and number of descriptors is defined by a descriptor set layout.
+	//
+	// Each descriptor set has a layout. A descriptor set layout object is defined by an array of
+	// zero or more descriptor bindings. Each individual descriptor binding is specified by
+	// a descriptor type, a count (array size) of the number of descriptors in the binding, a set
+	// of shader stages that can access the binding, and (if using immutable samplers) an array of
+	// sampler descriptors.
+
+	// {{{ Create Descriptor Set Layout
+	// Create a single binding with variable number of descriptors
+	u32 texture_count = (u32)wapp_array_count(textures);
+
+	VkDescriptorBindingFlags desc_variable_flag = VK_DESCRIPTOR_BINDING_VARIABLE_DESCRIPTOR_COUNT_BIT;
+
+	VkDescriptorSetLayoutBindingFlagsCreateInfo desc_binding_flags = {};
+	desc_binding_flags.sType                                       = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_BINDING_FLAGS_CREATE_INFO;
+	desc_binding_flags.bindingCount                                = 1;
+	desc_binding_flags.pBindingFlags                               = &desc_variable_flag;
+
+	VkDescriptorSetLayoutBinding desc_layout_binding_tex = {};
+	// We combine texture images and samplers, so the binding's type needs to be
+	// VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER
+	desc_layout_binding_tex.descriptorType               = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
+	desc_layout_binding_tex.descriptorCount              = texture_count;
+	// We only need to access this from the fragment shader, so we set stageFlags to
+	// VK_SHADER_STAGE_FRAGMENT_BIT
+	desc_layout_binding_tex.stageFlags                   = VK_SHADER_STAGE_FRAGMENT_BIT;
+
+	VkDescriptorSetLayoutCreateInfo desc_set_layout_create_info = {};
+	desc_set_layout_create_info.sType                           = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO;
+	desc_set_layout_create_info.pNext                           = &desc_binding_flags;
+	desc_set_layout_create_info.bindingCount                    = 1;
+	desc_set_layout_create_info.pBindings                       = &desc_layout_binding_tex;
+
+	check(vkCreateDescriptorSetLayout(device, &desc_set_layout_create_info, NULL, &desc_set_layout_tex));
+	// }}}
+
+	// {{{ Create Descriptor Pool To Allocate Descriptors
+	VkDescriptorPoolSize desc_pool_size = {};
+	desc_pool_size.type                 = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
+	desc_pool_size.descriptorCount      = texture_count;
+
+	VkDescriptorPoolCreateInfo desc_pool_create_info = {};
+	desc_pool_create_info.sType                      = VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO;
+	desc_pool_create_info.maxSets                    = 1;
+	desc_pool_create_info.poolSizeCount              = 1;
+	desc_pool_create_info.pPoolSizes                 = &desc_pool_size;
+
+	check(vkCreateDescriptorPool(device, &desc_pool_create_info, NULL, &desc_pool));
+	// }}}
+	
+	// {{{ Allocate Descriptor Sets
+	// Descriptor indexing allocate info
+	VkDescriptorSetVariableDescriptorCountAllocateInfo var_desc_count_alloc_info = {};
+	var_desc_count_alloc_info.sType                                              = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_VARIABLE_DESCRIPTOR_COUNT_ALLOCATE_INFO;
+	var_desc_count_alloc_info.descriptorSetCount                                 = 1;
+	var_desc_count_alloc_info.pDescriptorCounts                                  = &texture_count;
+
+	VkDescriptorSetAllocateInfo tex_desc_set_alloc_info = {};
+	tex_desc_set_alloc_info.sType                       = VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO;
+	tex_desc_set_alloc_info.pNext                       = &var_desc_count_alloc_info;
+	tex_desc_set_alloc_info.descriptorPool              = desc_pool;
+	tex_desc_set_alloc_info.descriptorSetCount          = 1;
+	tex_desc_set_alloc_info.pSetLayouts                 = &desc_set_layout_tex;
+
+	check(vkAllocateDescriptorSets(device, &tex_desc_set_alloc_info, &desc_set_tex));
+	// }}}
+
+	// {{{ Write Descriptor Set Data
+	VkWriteDescriptorSet write_desc_set_tex = {};
+	write_desc_set_tex.sType                = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET;
+	write_desc_set_tex.dstSet               = desc_set_tex;
+	write_desc_set_tex.dstBinding           = 0;
+	write_desc_set_tex.descriptorCount      = (u32)wapp_array_count(tex_descriptors);
+	write_desc_set_tex.descriptorType       = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER;
+	write_desc_set_tex.pImageInfo           = tex_descriptors;
+
+	vkUpdateDescriptorSets(device, 1, &write_desc_set_tex, 0, NULL);
+	// }}}
+	// }}}
 	// }}}
 
 	wapp_mem_arena_allocator_temp_end(&arena);
@@ -830,6 +919,8 @@ int main() {
 	// }}}
 
 	// {{{ Cleanup
+	vkDestroyDescriptorPool(device, desc_pool, NULL);
+	vkDestroyDescriptorSetLayout(device, desc_set_layout_tex, NULL);
 	for (u32 i = 0; i < wapp_array_count(textures); ++i) {
 		vkDestroySampler(device, textures[i].sampler, NULL);
 		vkDestroyImageView(device, textures[i].view, NULL);