From c998fcb4324e0e123057a88b688ae9f749b16d0d Mon Sep 17 00:00:00 2001
From: Trevor Hollmann <thollmann@uni-koblenz.de>
Date: Sun, 16 May 2021 10:55:05 +0200
Subject: [PATCH] [#26] Add first draft of Asset Loader API.
This commit adds the header for the asset loader module containing a
first draft of what the API for loading single meshes will look like.
Nothing is set in stone, all is up for discussion.
---
config/Sources.cmake | 3 +
include/asset_loader/asset_loader.hpp | 90 +++++++++++++++++++++++++++
src/asset_loader/main.cpp | 1 +
3 files changed, 94 insertions(+)
create mode 100644 include/asset_loader/asset_loader.hpp
create mode 100644 src/asset_loader/main.cpp
diff --git a/config/Sources.cmake b/config/Sources.cmake
index 80fa3a09..53d0bea7 100644
--- a/config/Sources.cmake
+++ b/config/Sources.cmake
@@ -12,4 +12,7 @@ set(vkcv_sources
${vkcv_include}/vkcv/Window.hpp
${vkcv_source}/vkcv/Window.cpp
+
+ ${vkcv_include}/asset_loader/asset_loader.hpp
+ ${vkcv_source}/asset_loader/main.cpp
)
diff --git a/include/asset_loader/asset_loader.hpp b/include/asset_loader/asset_loader.hpp
new file mode 100644
index 00000000..66e1b19a
--- /dev/null
+++ b/include/asset_loader/asset_loader.hpp
@@ -0,0 +1,90 @@
+#pragma once
+/**
+ * @authors Trevor Hollmann
+ * @file include/asset_loader/asset_loader.h
+ * @brief Interface of the asset loader module for the vkcv framework.
+ */
+
+#include <string>
+#include <vector>
+#include <cstdint>
+
+
+/* LOADING MESHES
+ * The description of meshes is a hierarchy of structures with the Mesh at the
+ * top.
+ *
+ * Each Mesh has an array of one or more vertex groups (called "primitives" in
+ * glFW parlance) and an array of zero or more Materials.
+ *
+ * Each vertex group describes a part of the meshes vertices by defining how
+ * they should be rendered (as points, lines, triangles), how many indices and
+ * vertices there are, how the content of the vertex buffer is to be
+ * interpreted and which material from the Meshes materials array should be
+ * used for the surface of the vertices.
+ * As a bonus there is also the axis aligned bounding box of the vertices.
+ *
+ * The vertex buffer is presented as a single block of binary data with a given
+ * length in bytes.
+ * The layout of the vertex buffer is described by an array of VertexAttribute
+ * structs that define the type of attribute, the offset, length and stride in
+ * bytes and number and type of components of the attribute.
+ * These values can directly be given to vulkan when describing the content of
+ * vertex buffers. */
+
+namespace asset {
+
+
+/* With these enums, 0 is reserved to signal uninitialized or invalid data. */
+enum PrimitiveMode { POINTS=1, LINES, TRIANGLES };
+enum PrimitiveType { POSITION=1, NORMAL, TEXCOORD_0 };
+
+typedef struct {
+ // TODO not yet needed for the first (unlit) triangle
+} Material;
+
+typedef struct {
+ PrimitiveType type; // POSITION, NORMAL, ...
+ uint32_t offset; // offset in bytes
+ uint32_t length; // length of ... in bytes
+ uint32_t stride; // stride in bytes
+ uint16_t componentType; // eg. 5126 for float
+ uint8_t componentCount; // eg. 3 for vec3
+} VertexAttribute;
+
+typedef struct {
+ enum PrimitiveMode mode; // draw as points, lines or triangle?
+ size_t numIndices, numVertices;
+ uint32_t *indices; // array of indices for indexed rendering
+ struct {
+ void *data; // the binary data of the buffer
+ size_t byteLength; // the length of the entire buffer in bytes
+ std::vector<VertexAttribute> attributes;
+ } vertexBuffer;
+ struct { float x, y, z; } min; // bounding box lower left
+ struct { float x, y, z; } max; // bounding box upper right
+ uint8_t materialIndex; // index to one of the meshes materials
+} VertexGroup;
+
+/* TODO This is just an initial draft of how a mesh loaded from a glTF file may
+ * be presented to other modules of the vkcv framework. */
+typedef struct {
+ std::string name;
+ std::vector<VertexGroup> vertexGroups;
+ std::vector<Material> materials;
+} Mesh;
+
+
+/**
+ * In its first iteration the asset loader module will only allow loading
+ * single meshes, one per glTF file.
+ * It will later be extended to allow loading entire scenes from glTF files.
+ *
+ * @param path must be the path to a glTF file containing a single mesh.
+ * @param mesh is a reference to a Mesh struct that will be filled with the
+ * content of the glTF file being loaded.
+ * */
+int loadMesh(const std::string &path, Mesh &mesh);
+
+
+}
diff --git a/src/asset_loader/main.cpp b/src/asset_loader/main.cpp
new file mode 100644
index 00000000..1e871e13
--- /dev/null
+++ b/src/asset_loader/main.cpp
@@ -0,0 +1 @@
+#include "asset_loader/asset_loader.hpp"
--
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