refactor: transparent render (#14)

* fix(renderer): defer uniform location retrieval and add view matrix in outline rendering

* refactor(gameplay): encapsulate per-type vertex data into VertexData struct

* feat(rendering): separate transparent blocks into discard and blend modes

* feat(renderer): implement order-independent transparency

* fix(shaders): reduce alpha discard threshold to 0.8

src/gameplay/vertex_data.cpp

@@ -0,0 +1,39 @@
+#include "Cubed/gameplay/vertex_data.hpp"
+
+#include "Cubed/gameplay/world.hpp"
+
+namespace Cubed {
+VertexData::VertexData(World& world) : m_world(world) {}
+VertexData::~VertexData() {
+    if (m_vbo != 0) {
+        m_world.push_delete_vbo(m_vbo);
+    }
+}
+VertexData::VertexData(VertexData&& o) noexcept
+    : m_vertices(std::move(o.m_vertices)), m_vbo(o.m_vbo),
+      m_sum(o.m_sum.load()), m_world(o.m_world) {
+    o.m_vbo = 0;
+    o.m_sum = 0;
+}
+VertexData& VertexData::operator=(VertexData&& o) noexcept {
+    m_vbo = o.m_vbo;
+    o.m_vbo = 0;
+    m_sum = o.m_sum.load();
+    o.m_sum = 0;
+    m_vertices = std::move(o.m_vertices);
+    return *this;
+}
+void VertexData::upload() {
+    if (m_vertices.size() == 0) {
+        return;
+    }
+    if (m_vbo == 0) {
+        glGenBuffers(1, &m_vbo);
+    }
+    glBindBuffer(GL_ARRAY_BUFFER, m_vbo);
+    glBufferData(GL_ARRAY_BUFFER, m_vertices.size() * sizeof(Vertex),
+                 m_vertices.data(), GL_DYNAMIC_DRAW);
+    glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+void VertexData::update_sum() { m_sum = m_vertices.size(); }
+} // namespace Cubed