From d9f10d25d0f420aeae189370662d34ca9027f763 Mon Sep 17 00:00:00 2001
From: praschke <stel@comfy.monster>
Date: Mon, 22 Aug 2022 13:30:14 +0000
Subject: [PATCH] shaderexp: use one triangle for fullscreen

---
 shaderexp/main.zig  |  2 +-
 shaderexp/vert.wgsl | 34 ++++++++++++++--------------------
 2 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/shaderexp/main.zig b/shaderexp/main.zig
index f055fb3f..a45a8a78 100755
--- a/shaderexp/main.zig
+++ b/shaderexp/main.zig
@@ -139,7 +139,7 @@ pub fn update(app: *App, core: *mach.Core) !void {
     const pass = encoder.beginRenderPass(&render_pass_info);
     pass.setPipeline(app.pipeline);
     pass.setBindGroup(0, app.bind_group, &.{0});
-    pass.draw(6, 1, 0, 0);
+    pass.draw(3, 1, 0, 0);
     pass.end();
     pass.release();
 
diff --git a/shaderexp/vert.wgsl b/shaderexp/vert.wgsl
index bce7ec2e..6f972316 100755
--- a/shaderexp/vert.wgsl
+++ b/shaderexp/vert.wgsl
@@ -1,29 +1,23 @@
 struct VertexOut {
-     @builtin(position) position_clip : vec4<f32>,
-     @location(0) frag_uv : vec2<f32>,
+    @builtin(position) position_clip : vec4<f32>,
+    @location(0) frag_uv : vec2<f32>,
 }
 
 @vertex fn main(@builtin(vertex_index) index : u32) -> VertexOut {
-    var pos = array<vec2<f32>, 6>(
-      vec2<f32>(-1.0, -1.0),
-      vec2<f32>( 1.0, -1.0),
-      vec2<f32>( 1.0,  1.0),
-      vec2<f32>( 1.0,  1.0),
-      vec2<f32>(-1.0,  1.0),
-      vec2<f32>(-1.0, -1.0)
+    var pos = array<vec2<f32>, 3>(
+        vec2<f32>(-1.0, -1.0),
+        vec2<f32>( 3.0, -1.0),
+        vec2<f32>(-1.0,  3.0),
     );
 
-    var uv = array<vec2<f32>, 6>(
-      vec2<f32>(0.0, 0.0),
-      vec2<f32>(1.0, 0.0),
-      vec2<f32>(1.0, 1.0),
-      vec2<f32>(1.0, 1.0),
-      vec2<f32>(0.0, 1.0),
-      vec2<f32>(0.0, 0.0)
+    var uv = array<vec2<f32>, 3>(
+        vec2<f32>(0.0, 0.0),
+        vec2<f32>(2.0, 0.0),
+        vec2<f32>(0.0, 2.0),
     );
 
-     var output : VertexOut;
-     output.position_clip = vec4<f32>(pos[index], 0.0, 1.0);
-     output.frag_uv = uv[index];
-     return output;
+    var output : VertexOut;
+    output.position_clip = vec4<f32>(pos[index], 0.0, 1.0);
+    output.frag_uv = uv[index];
+    return output;
 }