diff --git a/src/main.cpp b/src/main.cpp
index f382546..4bede5d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -31,6 +31,19 @@ struct RenderState
 
 	Assets* assets;
 
+	// FIXME: WIP
+	// TODO: need to initialize groups
+	u32 num_render_groups;
+	u32 max_render_groups;
+	RenderGroup* render_groups;
+
+	// TODO: need to initialize mappings
+	u32 num_mappings;
+	u32 max_mappings;
+	ShaderToRenderGroupMapping* mappings;
+	///
+
+	// TODO: can remove these after implementing render groups
 	u32 num_gl_meshes;
 	u32 max_gl_meshes;
 	GLmesh* gl_meshes;
diff --git a/src/shader.h b/src/shader.h
index d60abdf..a0b3216 100644
--- a/src/shader.h
+++ b/src/shader.h
@@ -8,27 +8,6 @@
 #include "types.h"
 
 
-struct gl_buffer
-{
-	GLuint id;
-	GLenum target;
-	GLenum data_type;
-	GLuint location; // NOTE: if used as backing for vertex attribute
-	GLuint binding_idx; // NOTE: if used as backing from unifor buffer object
-	char* name;
-};
-
-// NOTE: we need another struct for vertex attributes that mirrors gl_buffer
-// 	because an attribute is associated with a shader_programe while a buffer is
-// 	associated with the vertex data passed to glBufferData()
-struct GLVertexAttrib
-{
-	GLenum data_type;
-	u32 num_components;
-	GLuint location;
-	char* name;
-};
-
 struct gl_uniform
 {
 	// NOTE: would be nice to use idx as the location parameter because it seems
@@ -52,6 +31,17 @@ struct GLUniformBlock
 	char* name;
 };
 
+// NOTE: we need another struct for vertex attributes that mirrors gl_buffer
+// 	because an attribute is associated with a shader_program while a buffer is
+// 	associated with the vertex data passed to glBufferData()
+struct GLVertexAttrib
+{
+	GLenum data_type;
+	u32 num_components;
+	GLuint location;
+	char* name;
+};
+
 struct shader_program
 {
 	GLuint prog_id;
@@ -71,6 +61,15 @@ struct shader_program
 	u64 hash; // NOTE: hash of vs filpath + fs filepath concat
 };
 
+struct gl_buffer
+{
+	GLuint id;
+	GLenum target;
+	GLenum data_type;
+	GLuint binding_idx; // NOTE: if used as backing from uniform buffer object
+	char* name;
+};
+
 struct GLContext
 {
 	GLuint binding_count;
@@ -88,6 +87,13 @@ struct GLContext
 	shader_program* shaders;
 };
 
+struct GLBufferToAttribMapping
+{
+	const char* buf_name;
+	gl_buffer* buf;
+	GLVertexAttrib* attrib;
+};
+
 struct GLmesh
 {
 	u32 num_indices;
@@ -103,6 +109,13 @@ struct GLmesh
 	shader_program* shader;
 	glm::mat4* model_xform;
 
+	// FIXME: WIP
+	u32 max_vertex_buffers;
+	u32 num_vertex_buffers;
+	gl_buffer* vertex_buffers;
+	// WIP
+
+	// FIXME: replace IDs here with gl_buffer struct array?
 	GLuint vert_buf_id;
 	GLuint norm_buf_id;
 	GLuint uv_buf_id;
@@ -110,12 +123,38 @@ struct GLmesh
 	GLuint idx_buf_id;
 };
 
+// TODO: node/tree structure for entities
+struct Node;
+
+struct Entity
+{
+	u32 num_meshes;
+	GLmesh* meshes;
+};
+
+struct RenderGroup
+{
+	u32 num_entites;
+	u32 max_entities;
+	Entity* entities;
+	char* name;
+};
+
+struct ShaderToRenderGroupMapping
+{
+	shader_program* shader;
+	RenderGroup* render_group;
+};
+
+struct Animation;
+#if 0
 // NOTE: attempt to resolve GLmesh to shader_program mapping issue
 struct GLmeshMapping
 {
-	u32 mesh_idx;
+	u32 entity_idx;
 	u32 shader_idx;
 };
+#endif
 
 struct PointLight
 {
@@ -124,10 +163,6 @@ struct PointLight
 	u32 intensity;
 };
 
-struct node;
-struct entity;
-struct animation;
-
 struct transforms
 {
 	glm::mat4 view_xform;