From a57313b23ecb9843856ca0ea08635b6121fcb2cb Mon Sep 17 00:00:00 2001
From: Héctor Ramón Jiménez <hector@hecrj.dev>
Date: Thu, 2 May 2024 15:21:22 +0200
Subject: Simplify image rotation API and its internals

---
 wgpu/src/shader/image.wgsl | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

(limited to 'wgpu/src/shader/image.wgsl')

diff --git a/wgpu/src/shader/image.wgsl b/wgpu/src/shader/image.wgsl
index de962098..71bf939c 100644
--- a/wgpu/src/shader/image.wgsl
+++ b/wgpu/src/shader/image.wgsl
@@ -10,12 +10,11 @@ struct VertexInput {
     @builtin(vertex_index) vertex_index: u32,
     @location(0) pos: vec2<f32>,
     @location(1) center: vec2<f32>,
-    @location(2) image_size: vec2<f32>,
+    @location(2) scale: vec2<f32>,
     @location(3) rotation: f32,
-    @location(4) scale: vec2<f32>,
-    @location(5) atlas_pos: vec2<f32>,
-    @location(6) atlas_scale: vec2<f32>,
-    @location(7) layer: i32,
+    @location(4) atlas_pos: vec2<f32>,
+    @location(5) atlas_scale: vec2<f32>,
+    @location(6) layer: i32,
 }
 
 struct VertexOutput {
@@ -36,7 +35,7 @@ fn vs_main(input: VertexInput) -> VertexOutput {
     out.layer = f32(input.layer);
 
     // Calculate the vertex position and move the center to the origin
-    v_pos = input.pos + v_pos * input.image_size - input.center;
+    v_pos = input.pos + v_pos * input.scale - input.center;
 
     // Apply the rotation around the center of the image
     let cos_rot = cos(input.rotation);
@@ -48,16 +47,8 @@ fn vs_main(input: VertexInput) -> VertexOutput {
         vec4<f32>(0.0, 0.0, 0.0, 1.0)
     );
 
-    // Scale the image and then translate to the final position by moving the center to the position
-    let scale_translate = mat4x4<f32>(
-        vec4<f32>(input.scale.x, 0.0, 0.0, 0.0),
-        vec4<f32>(0.0, input.scale.y, 0.0, 0.0),
-        vec4<f32>(0.0, 0.0, 1.0, 0.0),
-        vec4<f32>(input.center, 0.0, 1.0)
-    );
-
     // Calculate the final position of the vertex
-    out.position = globals.transform * scale_translate * rotate * vec4<f32>(v_pos, 0.0, 1.0);
+    out.position = globals.transform * (vec4<f32>(input.center, 0.0, 0.0) + rotate * vec4<f32>(v_pos, 0.0, 1.0));
 
     return out;
 }
-- 
cgit