From b1c29c40fdc618ab250292f85d8132474fb8843e Mon Sep 17 00:00:00 2001
From: 3gg <3gg@shellblade.net>
Date: Fri, 24 Oct 2025 14:56:42 -0700
Subject: Fix Pong demo, add notes and TODOs

---
 include/gfx/llr/llr.h      |  6 ++++++
 include/gfx/llr/material.h |  1 +
 src/core/shader_program.h  |  2 --
 src/llr/llr.c              | 12 +++++++++++-
 src/llr/mesh_impl.h        |  2 +-
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/include/gfx/llr/llr.h b/include/gfx/llr/llr.h
index 098374d..f84b3fb 100644
--- a/include/gfx/llr/llr.h
+++ b/include/gfx/llr/llr.h
@@ -14,6 +14,9 @@ typedef struct Skeleton      Skeleton;
 
 typedef struct LLR LLR;
 
+// -----------------------------------------------------------------------------
+// Low-level rendering.
+
 /// Set the shader to be used for subsequent draw calls.
 /// The shader is not yet activated at this point.
 void gfx_llr_set_shader(LLR*, ShaderProgram*);
@@ -44,6 +47,9 @@ void gfx_llr_set_material(LLR*, const Material*);
 /// Set the camera.
 void gfx_llr_set_camera(LLR*, const Camera*);
 
+/// Set the projection matrix.
+void gfx_llr_set_projection_matrix(LLR* renderer, const mat4* projection);
+
 /// Set the aspect ratio.
 void gfx_llr_set_aspect(LLR*, float aspect);
 
diff --git a/include/gfx/llr/material.h b/include/gfx/llr/material.h
index bca664e..9ebf9b3 100644
--- a/include/gfx/llr/material.h
+++ b/include/gfx/llr/material.h
@@ -7,6 +7,7 @@ typedef struct Material Material;
 
 /// Describes a material.
 ///
+/// TODO: It doesn't hold the shader program anymore...It's in the Mesh.
 /// A material holds a shader program and a set of shader-specific uniform
 /// variables. Two materials can share the same shader, but shader parameters
 /// generally give two materials a different appearance.
diff --git a/src/core/shader_program.h b/src/core/shader_program.h
index 1443663..521118d 100644
--- a/src/core/shader_program.h
+++ b/src/core/shader_program.h
@@ -5,8 +5,6 @@
 
 #include "gl_util.h"
 
-#include <math/fwd.h>
-
 #include <stdbool.h>
 
 typedef struct Texture Texture;
diff --git a/src/llr/llr.c b/src/llr/llr.c
index fe02c0d..25cdf9f 100644
--- a/src/llr/llr.c
+++ b/src/llr/llr.c
@@ -204,7 +204,10 @@ static void configure_state(LLR* renderer) {
   if (renderer->material_changed || renderer->shader_changed) {
     renderer->material_changed = false;
 
-    gfx_material_activate(renderer->shader, renderer->material);
+    // Geometry may be rendered without a material.
+    if (renderer->material) {
+      gfx_material_activate(renderer->shader, renderer->material);
+    }
   }
 
   if (renderer->shader_changed) {
@@ -330,6 +333,13 @@ void gfx_llr_set_camera(LLR* renderer, const Camera* camera) {
   renderer->camera_changed = true;
 }
 
+void gfx_llr_set_projection_matrix(LLR* renderer, const mat4* projection) {
+  assert(renderer);
+
+  renderer->projection     = *projection;
+  renderer->camera_changed = true;
+}
+
 void gfx_llr_set_aspect(LLR* renderer, float aspect) {
   assert(renderer);
 
diff --git a/src/llr/mesh_impl.h b/src/llr/mesh_impl.h
index 96e60df..a997d5b 100644
--- a/src/llr/mesh_impl.h
+++ b/src/llr/mesh_impl.h
@@ -5,5 +5,5 @@
 typedef struct Mesh {
   const Geometry* geometry;
   const Material* material;
-  ShaderProgram*  shader;
+  ShaderProgram*  shader; // TODO: Move this back to Material?
 } Mesh;
-- 
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