Add instanced rendering :3

Shaders/shader.vert

@@ -2,6 +2,7 @@
 
 layout(location = 0) in vec2 inPosition;
 layout(location = 1) in vec3 inColor;
+layout(location = 2) in mat3 offset;
 
 layout(set = 0, binding = 0) uniform UBO {
     mat3 model;
@@ -13,7 +14,7 @@ layout(location = 0) out vec3 fragColor;
 layout(location = 1) out vec2 fragUV;
 
 void main() {
-    gl_Position = vec4(ubo.proj * ubo.view * ubo.model * vec3(inPosition, 1.0), 1.0);
+    gl_Position = vec4(ubo.proj * ubo.view * offset * ubo.model * vec3(inPosition, 1.0), 1.0);
     fragColor = inColor;
     fragUV = inPosition;
 }

kitty.c

@@ -13,6 +13,7 @@ struct Kitty *kitty_make() {
   memset(kitty, 0, sizeof(struct Kitty));
   dyn_array_create_inplace(&kitty->attatchments);
   dyn_array_create_inplace(&kitty->vertex_buffer.format);
+  dyn_array_create_inplace(&kitty->instance_buffer.format);
   meow("alloced a kitty at %p", kitty);
   return kitty;
 }
@@ -40,8 +41,18 @@ void kitty_add_index_buffer(struct Kitty *kitty, void *data, uint32_t count) {
   kitty->index_buffer.count = count;
 }
 
+void kitty_add_instance_buffer(struct Kitty *kitty, void *data, uint32_t count,
+                               int element_size) {
+  kitty->instance_buffer.data = data;
+  kitty->instance_buffer.count = count;
+  kitty->instance_buffer.element_size = element_size;
+}
+void kitty_add_instance_buffer_format(struct Kitty *kitty,
+                                      enum VkFormat format) {
+  dyn_array_append(&kitty->instance_buffer.format, format);
+}
+
 void kitty_add_vertex_buffer_format(struct Kitty *kitty, enum VkFormat format) {
-  meow("attatched %d to the buffer", format);
   dyn_array_append(&kitty->vertex_buffer.format, format);
 }
 void kitty_attatch_image(struct Kitty *kitty, const char *path) {
@@ -68,6 +79,9 @@ void kitty_finalise(struct Vk *state, struct Kitty *kitty) {
   kitty_create_ubo_attatchments(kitty, state);
   kitty_create_descriptor_sets(kitty, state);
   kitty_create_vertex_buffer(kitty, state);
+  if (kitty->instance_buffer.count != 0) {
+    kitty_create_instance_buffer(kitty, state);
+  }
 
   dyn_array_append(&state->kitties, kitty);
 }
@@ -76,6 +90,10 @@ void free_kitty(struct Vk *state, struct Kitty *kitty) {
   vkDeviceWaitIdle(state->device);
   vkDestroyBuffer(state->device, kitty->vertex_buffer.buffer, NULL);
   vkFreeMemory(state->device, kitty->vertex_buffer.memory, NULL);
+  if (kitty->instance_buffer.count != 0) {
+    vkDestroyBuffer(state->device, kitty->instance_buffer.buffer, NULL);
+    vkFreeMemory(state->device, kitty->instance_buffer.memory, NULL);
+  }
   vkDestroyDescriptorPool(state->device, kitty->descriptor_pool, NULL);
   vkDestroyDescriptorSetLayout(state->device, kitty->descriptor_set_layout,
                                NULL);
@@ -142,16 +160,26 @@ void kitty_draw(struct Vk *state, uint32_t image_index, struct Kitty *kitty) {
   scissor.extent = (VkExtent2D){state->width, state->heigh};
   vkCmdSetScissor(flight.command_buffer, 0, 1, &scissor);
 
-  VkBuffer vertex_buffer[] = {kitty->vertex_buffer.buffer};
+  uint64_t offsets[1] = {0};
-  VkDeviceSize offsets[] = {0};
+  vkCmdBindVertexBuffers(flight.command_buffer, 0, 1,
-  vkCmdBindVertexBuffers(flight.command_buffer, 0, 1, vertex_buffer, offsets);
+                         &kitty->vertex_buffer.buffer, offsets);
+
+  if (kitty->instance_buffer.count != 0) {
+    vkCmdBindVertexBuffers(flight.command_buffer, 1, 1,
+                           &kitty->instance_buffer.buffer, offsets);
+  }
 
   vkCmdBindDescriptorSets(
       flight.command_buffer, VK_PIPELINE_BIND_POINT_GRAPHICS,
       kitty->pipeline_layout, 0, 1,
       &kitty->descriptor_sets[state->current_frame], 0, NULL);
 
-  vkCmdDraw(flight.command_buffer, kitty->vertex_buffer.count, 1, 0, 0);
+  if (kitty->instance_buffer.count == 0) {
+    vkCmdDraw(flight.command_buffer, kitty->vertex_buffer.count, 1, 0, 0);
+  } else {
+    vkCmdDraw(flight.command_buffer, kitty->vertex_buffer.count,
+              kitty->instance_buffer.count, 0, 0);
+  }
 }
 
 void kitty_create_layout_bindings(struct Kitty *kitty, struct Vk *state) {
@@ -210,33 +238,79 @@ void kitty_create_pipeline(struct Kitty *kitty, struct Vk *state) {
 
   VkPipelineShaderStageCreateInfo shader_stage_info[] = {vert_stage_info,
                                                          frag_stage_info};
-  VkVertexInputBindingDescription vertex_binding_description = {0};
-  vertex_binding_description.binding = 0;
-  vertex_binding_description.stride = kitty->vertex_buffer.vertex_size;
-  vertex_binding_description.inputRate = VK_VERTEX_INPUT_RATE_VERTEX;
-
-  VkVertexInputAttributeDescription *vertex_attribute_descriptions =
-      alloca(sizeof(VkVertexInputAttributeDescription) *
-             kitty->vertex_buffer.format.count);
-  int offset = 0;
-  for (int i = 0; i < kitty->vertex_buffer.format.count; i++) {
-    vertex_attribute_descriptions[i].binding = 0;
-    vertex_attribute_descriptions[i].location = i;
-    vertex_attribute_descriptions[i].format =
-        kitty->vertex_buffer.format.items[i];
-    vertex_attribute_descriptions[i].offset = offset;
-    offset += get_size_of_format(kitty->vertex_buffer.format.items[i]);
-  }
 
   VkPipelineVertexInputStateCreateInfo vertex_input_info = {0};
-  vertex_input_info.sType =
+  if (kitty->instance_buffer.count == 0) {
-      VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
+    meow("single instance kitty");
-  vertex_input_info.vertexBindingDescriptionCount = 1;
+    VkVertexInputBindingDescription vertex_binding_description = {0};
-  vertex_input_info.pVertexBindingDescriptions = &vertex_binding_description;
+    vertex_binding_description.binding = 0;
-  vertex_input_info.vertexAttributeDescriptionCount =
+    vertex_binding_description.stride = kitty->vertex_buffer.vertex_size;
-      kitty->vertex_buffer.format.count;
+    vertex_binding_description.inputRate = VK_VERTEX_INPUT_RATE_VERTEX;
-  vertex_input_info.pVertexAttributeDescriptions =
+
-      vertex_attribute_descriptions;
+    VkVertexInputAttributeDescription *vertex_attribute_descriptions =
+        alloca(sizeof(VkVertexInputAttributeDescription) *
+               kitty->vertex_buffer.format.count);
+    int offset = 0;
+    for (int i = 0; i < kitty->vertex_buffer.format.count; i++) {
+      vertex_attribute_descriptions[i].binding = 0;
+      vertex_attribute_descriptions[i].location = i;
+      vertex_attribute_descriptions[i].format =
+          kitty->vertex_buffer.format.items[i];
+      vertex_attribute_descriptions[i].offset = offset;
+      offset += get_size_of_format(kitty->vertex_buffer.format.items[i]);
+    }
+
+    vertex_input_info.sType =
+        VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
+    vertex_input_info.vertexBindingDescriptionCount = 1;
+    vertex_input_info.pVertexBindingDescriptions = &vertex_binding_description;
+    vertex_input_info.vertexAttributeDescriptionCount =
+        kitty->vertex_buffer.format.count;
+    vertex_input_info.pVertexAttributeDescriptions =
+        vertex_attribute_descriptions;
+  } else {
+    meow("multi instance kitty");
+    VkVertexInputBindingDescription binding_descriptions[2] = {0};
+    binding_descriptions[0].binding = 0;
+    binding_descriptions[0].stride = kitty->vertex_buffer.vertex_size;
+    binding_descriptions[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;
+    binding_descriptions[1].binding = 1;
+    binding_descriptions[1].stride = kitty->instance_buffer.element_size;
+    binding_descriptions[1].inputRate = VK_VERTEX_INPUT_RATE_INSTANCE;
+
+    VkVertexInputAttributeDescription *attribute_descriptions =
+        alloca(sizeof(VkVertexInputAttributeDescription) *
+                   kitty->vertex_buffer.format.count +
+               sizeof(VkVertexInputAttributeDescription) *
+                   kitty->instance_buffer.format.count);
+    int offset = 0;
+    for (int i = 0; i < kitty->vertex_buffer.format.count; i++) {
+      attribute_descriptions[i].binding = 0;
+      attribute_descriptions[i].location = i;
+      attribute_descriptions[i].format = kitty->vertex_buffer.format.items[i];
+      attribute_descriptions[i].offset = offset;
+      offset += get_size_of_format(kitty->vertex_buffer.format.items[i]);
+    }
+    offset = 0;
+    for (int i = 0; i < kitty->instance_buffer.format.count; i++) {
+      attribute_descriptions[i + kitty->vertex_buffer.format.count].binding = 1;
+      attribute_descriptions[i + kitty->vertex_buffer.format.count].location =
+          i + kitty->vertex_buffer.format.count;
+      attribute_descriptions[i + kitty->vertex_buffer.format.count].format =
+          kitty->instance_buffer.format.items[i];
+      attribute_descriptions[i + kitty->vertex_buffer.format.count].offset =
+          offset;
+      offset += get_size_of_format(kitty->instance_buffer.format.items[i]);
+    }
+
+    vertex_input_info.sType =
+        VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO;
+    vertex_input_info.vertexBindingDescriptionCount = 2;
+    vertex_input_info.pVertexBindingDescriptions = binding_descriptions;
+    vertex_input_info.vertexAttributeDescriptionCount =
+        kitty->vertex_buffer.format.count + kitty->instance_buffer.format.count;
+    vertex_input_info.pVertexAttributeDescriptions = attribute_descriptions;
+  }
 
   VkPipelineInputAssemblyStateCreateInfo input_assembly_info = {0};
   input_assembly_info.sType =
@@ -543,3 +617,36 @@ void kitty_create_vertex_buffer(struct Kitty *kitty, struct Vk *state) {
   vkFreeMemory(state->device, staging_buffer_memory, NULL);
   kitty->vertex_buffer.data = NULL;
 }
+
+void kitty_create_instance_buffer(struct Kitty *kitty, struct Vk *state) {
+  if (kitty->instance_buffer.count == 0) {
+    crash("trying to create an instance buffer for a kitty that is not "
+          "instanced :o");
+  }
+  VkDeviceSize size =
+      kitty->instance_buffer.count * kitty->instance_buffer.element_size;
+  VkBuffer staging_buffer;
+  VkDeviceMemory staging_buffer_memory;
+
+  create_buffer(state, size, VK_BUFFER_USAGE_TRANSFER_SRC_BIT,
+                VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT |
+                    VK_MEMORY_PROPERTY_HOST_COHERENT_BIT,
+                &staging_buffer, &staging_buffer_memory);
+
+  void *data;
+  vkMapMemory(state->device, staging_buffer_memory, 0, size, 0, &data);
+  memcpy(data, kitty->instance_buffer.data, size);
+  vkUnmapMemory(state->device, staging_buffer_memory);
+
+  create_buffer(state, size,
+                VK_BUFFER_USAGE_TRANSFER_DST_BIT |
+                    VK_BUFFER_USAGE_VERTEX_BUFFER_BIT,
+                VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT,
+                &kitty->instance_buffer.buffer, &kitty->instance_buffer.memory);
+
+  copy_buffer(state, staging_buffer, kitty->instance_buffer.buffer, size);
+
+  vkDestroyBuffer(state->device, staging_buffer, NULL);
+  vkFreeMemory(state->device, staging_buffer_memory, NULL);
+  kitty->instance_buffer.data = NULL;
+}

kitty.h

@@ -42,6 +42,7 @@ struct Kitty {
   const char *fragment_path;
 
   struct VertexBuffer vertex_buffer;
+  struct InstanceBuffer instance_buffer;
   struct IndexBuffer index_buffer;
 
   struct da_Attatchment attatchments;
@@ -68,6 +69,13 @@ void kitty_add_vertex_buffer_format(struct Kitty *thingy, enum VkFormat format);
 // transferred
 void kitty_add_index_buffer(struct Kitty *kitty, void *data, uint32_t count);
 
+// 'data' can be freed after 'kitty_finalise' is called, ownership is not
+// transferred
+void kitty_add_instance_buffer(struct Kitty *kitty, void *data, uint32_t count,
+                               int element_size);
+void kitty_add_instance_buffer_format(struct Kitty *kitty,
+                                      enum VkFormat format);
+
 void kitty_set_push_constant_size(struct Kitty *thingy, uint32_t size);
 
 // the returned number can be used in 'kitty_set_next_ubo' to update the content
@@ -92,5 +100,6 @@ void kitty_create_image_attatchments(struct Kitty *kitty, struct Vk *state);
 void kitty_create_ubo_attatchments(struct Kitty *kitty, struct Vk *state);
 void kitty_create_descriptor_sets(struct Kitty *kitty, struct Vk *state);
 void kitty_create_vertex_buffer(struct Kitty *kitty, struct Vk *state);
+void kitty_create_instance_buffer(struct Kitty *kitty, struct Vk *state);
 
 #endif // INCLUDE_KITTY

vulkan.h

@@ -28,7 +28,15 @@ struct VertexBuffer {
   VkDeviceMemory memory;
   uint32_t count;
   int vertex_size;
-  int binding;
+  struct da_VK_FORMAT format;
+};
+
+struct InstanceBuffer {
+  void *data;
+  VkBuffer buffer;
+  VkDeviceMemory memory;
+  uint32_t count;
+  int element_size;
   struct da_VK_FORMAT format;
 };