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

assets/shaders/block_accumulation_v_shader.glsl

@@ -0,0 +1,21 @@
+#version 460
+
+layout (location = 0) in vec3 pos;
+layout (location = 1) in vec2 texCoord;
+layout (location = 2) in float layer;
+out vec2 tc;
+flat out int tex_layer;
+out float v_depth;
+
+uniform mat4 mv_matrix;
+uniform mat4 proj_matrix;
+
+
+
+void main(void) {
+    vec4 view_pos = mv_matrix * vec4(pos, 1.0);
+    gl_Position = proj_matrix * view_pos;
+    tc = texCoord;
+    tex_layer = int(layer);
+    v_depth = -view_pos.z;
+}