initialize GLBuffer members to sane defaults at creation

src/shader.cpp

@@ -49,6 +49,14 @@ initGLContext(MemoryArena* arena,
 	gl_ctx->shaders = ARENA_ALLOC(arena, ShaderProgram, max_shaders);
 	gl_ctx->max_ubos = max_ubos;
 	gl_ctx->uniform_buffers = ARENA_ALLOC(arena, GLBuffer, max_ubos);
+
+	// NOTE: initialize GLBuffer struct members to sane defaults
+	for (u32 i = 0; i < max_ubos; i++) {
+		GLBuffer& buf = gl_ctx->uniform_buffers[i];
+		buf.location = -1;
+		buf.binding_idx = -1;
+	}
+
 	gl_ctx->max_textures = max_textures;
 	gl_ctx->textures = ARENA_ALLOC(arena, GLTexture, max_textures);
 

src/shader.h

@@ -89,10 +89,8 @@ struct GLBuffer
 	GLenum target;
 	GLenum data_type;
 	GLuint data_size; // NOTE: size of buffer in bytes
-	// FIXME: we should initialize both of these to UINT_MAX because '0' is a
-	// 	valid location and index
-	GLuint location; // NOTE: if used as backing for vertex attribute
-	GLuint binding_idx; // NOTE: if used as backing from uniform buffer object
+	GLint location; // NOTE: if used as backing for vertex attribute
+	GLint binding_idx; // NOTE: if used as backing from uniform buffer object
 	char* name;
 };