From 5bbe2204f1d30e99ee442e287167ef14ad51af75 Mon Sep 17 00:00:00 2001
From: skal <pascal.massimino@gmail.com>
Date: Wed, 28 Jan 2026 02:06:05 +0100
Subject: fix(gpu): Add aspect ratio correction to shader

Implements aspect ratio correction to prevent the pulsating heptagon from being distorted when the window is resized.

- The main loop now queries the framebuffer size and calculates the aspect ratio each frame.

- This aspect ratio is passed to the GPU via an updated uniform buffer.

- The vertex shader in shader.wgsl now uses the aspect ratio to correctly scale the X coordinates of the vertices, ensuring the shape remains proportional.
---
 src/gpu/gpu.cc | 21 +++++++++++++++------
 src/gpu/gpu.h  |  2 +-
 2 files changed, 16 insertions(+), 7 deletions(-)

(limited to 'src/gpu')

diff --git a/src/gpu/gpu.cc b/src/gpu/gpu.cc
index 9eb2437..707ffe2 100644
--- a/src/gpu/gpu.cc
+++ b/src/gpu/gpu.cc
@@ -7,6 +7,7 @@
 
 #include <algorithm>
 #include <cassert>
+#include <cstdint>
 #include <cstring>
 #include <vector>
 
@@ -86,6 +87,7 @@ static void handle_device_error(WGPUDevice const *device, WGPUErrorType type,
 const char *shader_wgsl_code = R"(
 struct Uniforms {
     audio_peak : f32,
+    aspect_ratio: f32,
 };
 
 @group(0) @binding(0) var<uniform> uniforms : Uniforms;
@@ -108,7 +110,7 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32) -> @builtin(position) vec4<
     
     let i = tri_idx + f32(sub_idx - 1u);
     let angle = i * 2.0 * PI / num_sides;
-    let x = scale * cos(angle);
+    let x = scale * cos(angle) / uniforms.aspect_ratio;
     let y = scale * sin(angle);
     
     return vec4<f32>(x, y, 0.0, 1.0);
@@ -179,14 +181,14 @@ void gpu_init(GLFWwindow *window) {
   WGPUBufferDescriptor uniform_buffer_desc = {};
   uniform_buffer_desc.label = str_view("Uniform Buffer");
   uniform_buffer_desc.usage = WGPUBufferUsage_Uniform | WGPUBufferUsage_CopyDst;
-  uniform_buffer_desc.size = sizeof(float);
+  uniform_buffer_desc.size = sizeof(float) * 2;
   g_uniform_buffer = wgpuDeviceCreateBuffer(g_device, &uniform_buffer_desc);
 
   WGPUBindGroupLayoutEntry bgl_entry = {};
   bgl_entry.binding = 0;
   bgl_entry.visibility = WGPUShaderStage_Vertex | WGPUShaderStage_Fragment;
   bgl_entry.buffer.type = WGPUBufferBindingType_Uniform;
-  bgl_entry.buffer.minBindingSize = sizeof(float);
+  bgl_entry.buffer.minBindingSize = sizeof(float) * 2;
 
   WGPUBindGroupLayoutDescriptor bgl_desc = {};
   bgl_desc.entryCount = 1;
@@ -197,7 +199,7 @@ void gpu_init(GLFWwindow *window) {
   WGPUBindGroupEntry bg_entry = {};
   bg_entry.binding = 0;
   bg_entry.buffer = g_uniform_buffer;
-  bg_entry.size = sizeof(float);
+  bg_entry.size = sizeof(float) * 2;
 
   WGPUBindGroupDescriptor bg_desc = {};
   bg_desc.layout = bind_group_layout;
@@ -236,6 +238,7 @@ void gpu_init(GLFWwindow *window) {
   glfwGetFramebufferSize(window, &width, &height);
   g_config.device = g_device;
   g_config.format = swap_chain_format;
+  g_config.usage = WGPUTextureUsage_RenderAttachment;
   g_config.width = width;
   g_config.height = height;
   g_config.presentMode = WGPUPresentMode_Fifo;
@@ -244,7 +247,7 @@ void gpu_init(GLFWwindow *window) {
   wgpuSurfaceConfigure(g_surface, &g_config);
 }
 
-void gpu_draw(float audio_peak) {
+void gpu_draw(float audio_peak, float aspect_ratio) {
   WGPUSurfaceTexture surface_texture;
   wgpuSurfaceGetCurrentTexture(g_surface, &surface_texture);
   if (surface_texture.status != WGPUSurfaceGetCurrentTextureStatus_SuccessOptimal &&
@@ -253,7 +256,11 @@ void gpu_draw(float audio_peak) {
 
   WGPUTextureView view = wgpuTextureCreateView(surface_texture.texture, nullptr);
 
-  wgpuQueueWriteBuffer(g_queue, g_uniform_buffer, 0, &audio_peak, sizeof(float));
+  struct {
+    float audio_peak;
+    float aspect_ratio;
+  } uniforms = {audio_peak, aspect_ratio};
+  wgpuQueueWriteBuffer(g_queue, g_uniform_buffer, 0, &uniforms, sizeof(uniforms));
 
   WGPUCommandEncoderDescriptor encoder_desc = {};
   WGPUCommandEncoder encoder =
@@ -261,9 +268,11 @@ void gpu_draw(float audio_peak) {
 
   WGPURenderPassColorAttachment color_attachment = {};
   color_attachment.view = view;
+  color_attachment.resolveTarget = nullptr;
   color_attachment.loadOp = WGPULoadOp_Clear;
   color_attachment.storeOp = WGPUStoreOp_Store;
   color_attachment.clearValue = {0.1, 0.2, 0.3, 1.0};
+  color_attachment.depthSlice = WGPU_DEPTH_SLICE_UNDEFINED;
 
   WGPURenderPassDescriptor render_pass_desc = {};
   render_pass_desc.colorAttachmentCount = 1;
diff --git a/src/gpu/gpu.h b/src/gpu/gpu.h
index 127ca42..87d4b9b 100644
--- a/src/gpu/gpu.h
+++ b/src/gpu/gpu.h
@@ -2,5 +2,5 @@
 struct GLFWwindow;
 
 void gpu_init(GLFWwindow *window);
-void gpu_draw(float audio_peak);
+void gpu_draw(float audio_peak, float aspect_ratio);
 void gpu_shutdown();
-- 
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