From 2faee35680a3dd4649cd22ac85cca3b656cc1d4b Mon Sep 17 00:00:00 2001
From: Sven Balzer <4653051+Kyuusokuna@users.noreply.github.com>
Date: Sat, 8 Aug 2026 17:18:59 +0200
Subject: [PATCH] add letter-/pillar- boxing for aspect ratios outside fo the
 defined min/max

---
 src/main.cpp          | 25 ++++++++++++++++++++++---
 src/renderer.h        |  1 +
 src/renderer_sdlgpu.c |  4 ++++
 src/renderer_wgpu.c   |  4 ++++
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index b51c21e..2725b36 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -37,6 +37,9 @@ using namespace glm;
 #define TILE_ATLAS_SIZE      (512)
 #define PLACEABLE_ATLAS_SIZE (256)
 
+#define ASPECT_RATIO_MIN ( 1.0f / 1.0f)
+#define ASPECT_RATIO_MAX (16.0f / 9.0f)
+
 static SDL_Window *window;
 static R_Texture  framebuffer;
 
@@ -59,6 +62,9 @@ static R_Buffer placeable_sizes_and_offsets_buffer;
 
 static i32vec2 window_size = { 1280, 720 };
 
+static vec2 viewport_position;
+static vec2 viewport_size;
+
 static MIX_Mixer *mixer;
 static MIX_Track *music_track;
 static MIX_Track *sfx_track;
@@ -1947,13 +1953,25 @@ static void render_game() {
         {
             ZoneScopedN("per_frame");
 
-            float aspect_ratio = ((float)window_size.x / (float)window_size.y);
+            viewport_position = vec2(0.0f, 0.0f);
+            viewport_size     = vec2(window_size.x, window_size.y);
+
+            float window_aspect_ratio   = ((float)window_size.x / (float)window_size.y);
+            float viewport_aspect_ratio = clamp(window_aspect_ratio, ASPECT_RATIO_MIN, ASPECT_RATIO_MAX);
+
+            if (window_aspect_ratio > viewport_aspect_ratio) {
+                viewport_size.x     = viewport_size.y * viewport_aspect_ratio;
+                viewport_position.x = (window_size.x - viewport_size.x) * 0.5f; 
+            } else {
+                viewport_size.y     = viewport_size.x / viewport_aspect_ratio;
+                viewport_position.y = (window_size.y - viewport_size.y) * 0.5f;
+            }
 
             view_matrix         = view        (vec3(player.visual_position, 0), radians(camera_tilt), camera_distance);
             inverse_view_matrix = inverse_view(vec3(player.visual_position, 0), radians(camera_tilt), camera_distance);
 
-            projection_matrix         = projection        (radians(camera_fovy_degrees), aspect_ratio, NEAR_PLANE);
-            inverse_projection_matrix = inverse_projection(radians(camera_fovy_degrees), aspect_ratio, NEAR_PLANE);
+            projection_matrix         = projection        (radians(camera_fovy_degrees), viewport_aspect_ratio, NEAR_PLANE);
+            inverse_projection_matrix = inverse_projection(radians(camera_fovy_degrees), viewport_aspect_ratio, NEAR_PLANE);
 
             mat4x4 view_projection_matrix = view_matrix * projection_matrix;
             renderer_buffer_update(view_projection_matrix_buffer, 0, sizeof(view_projection_matrix), &view_projection_matrix);
@@ -1990,6 +2008,7 @@ static void render_game() {
     }
 
     renderer_frame_set_target(framebuffer, R_surface, R_LOAD_OP_CLEAR, R_STORE_OP_STORE, { 0.01f, 0.01f, 0.01f, 0.01f });
+    renderer_frame_set_viewport(viewport_position.x, viewport_position.y, viewport_size.x, viewport_size.y, 0.0f, 1.0f);
 
     {
         ZoneScopedN("Draw Map");
diff --git a/src/renderer.h b/src/renderer.h
index 9578014..5afcd55 100644
--- a/src/renderer.h
+++ b/src/renderer.h
@@ -114,6 +114,7 @@ void renderer_frame_end();
 
 void renderer_frame_set_target(R_Texture target, R_Texture resolve_target, R_Load_Op load_op, R_Store_Op store_op, R_Color clear_color);
 void renderer_frame_set_shader(R_Shader shader);
+void renderer_frame_set_viewport(float x, float y, float width, float height, float min_depth, float max_depth);
 void renderer_frame_draw(R_Buffer vertex_buffer, R_Buffer index_buffer, R_Buffer instance_buffer, Uint32 num_indices, Uint32 num_instances, const R_Draw_Resources *resources);
 
 // Dear ImGui
diff --git a/src/renderer_sdlgpu.c b/src/renderer_sdlgpu.c
index bdc25ba..56719ac 100644
--- a/src/renderer_sdlgpu.c
+++ b/src/renderer_sdlgpu.c
@@ -331,6 +331,10 @@ void renderer_frame_set_shader(R_Shader shader) {
     SDL_BindGPUGraphicsPipeline(render_pass, shaders[shader]);
 }
 
+void renderer_frame_set_viewport(float x, float y, float width, float height, float min_depth, float max_depth) {
+    SDL_SetGPUViewport(render_pass, &(SDL_GPUViewport){ .x = x, .y = y, .w = width, .h = height, .min_depth = min_depth, .max_depth = max_depth });
+}
+
 void renderer_frame_draw(R_Buffer vertex_buffer, R_Buffer index_buffer, R_Buffer instance_buffer, Uint32 num_indices, Uint32 num_instances, const R_Draw_Resources *resources) {
     SDL_assert(render_pass);
 
diff --git a/src/renderer_wgpu.c b/src/renderer_wgpu.c
index 2ec5d0e..f1ae853 100644
--- a/src/renderer_wgpu.c
+++ b/src/renderer_wgpu.c
@@ -333,6 +333,10 @@ void renderer_frame_set_shader(R_Shader shader) {
     current_shader = shader;
 }
 
+void renderer_frame_set_viewport(float x, float y, float width, float height, float min_depth, float max_depth) {
+    wgpuRenderPassEncoderSetViewport(pass_encoder, x, y, width, height, min_depth, max_depth);
+}
+
 void renderer_frame_draw(R_Buffer vertex_buffer, R_Buffer index_buffer, R_Buffer instance_buffer, Uint32 num_indices, Uint32 num_instances, const R_Draw_Resources *resources) {
     SDL_assert(pass_encoder);