From ea0265f021ff14b816350d0412d795d47038590e Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sat, 29 Oct 2022 14:49:01 -0700
Subject: [PATCH] projection matrix, render cell

---
 src/renderer/Metal.zig | 28 ++++++++++++++++++++++++++++
 src/shaders/cell.metal | 22 ++++++++++++++--------
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/src/renderer/Metal.zig b/src/renderer/Metal.zig
index 7dc2c1373..80d4e3d02 100644
--- a/src/renderer/Metal.zig
+++ b/src/renderer/Metal.zig
@@ -9,6 +9,7 @@ const macos = @import("macos");
 const font = @import("../font/main.zig");
 const terminal = @import("../terminal/main.zig");
 const renderer = @import("../renderer.zig");
+const math = @import("../math.zig");
 const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const Terminal = terminal.Terminal;
@@ -52,6 +53,11 @@ const GPUCell = extern struct {
     foo: f64,
 };
 
+const GPUUniforms = extern struct {
+    projection_matrix: math.Mat,
+    cell_size: [2]f32,
+};
+
 /// Returns the hints that we want for this
 pub fn windowHints() glfw.Window.Hints {
     return .{
@@ -340,6 +346,19 @@ pub fn render(
     const bounds = self.swapchain.getProperty(macos.graphics.Rect, "bounds");
     self.swapchain.setProperty("drawableSize", bounds.size);
 
+    // Setup our uniforms
+    const uniforms: GPUUniforms = .{
+        .projection_matrix = math.ortho2d(
+            0,
+            @floatCast(f32, bounds.size.width),
+            @floatCast(f32, bounds.size.height),
+            0,
+        ),
+
+        // TODO: get content scale to scale these
+        .cell_size = .{ self.cell_size.width / 2, self.cell_size.height / 2 },
+    };
+
     // Get our surface (CAMetalDrawable)
     const surface = self.swapchain.msgSend(objc.Object, objc.sel("nextDrawable"), .{});
 
@@ -399,6 +418,15 @@ pub fn render(
             objc.sel("setVertexBuffer:offset:atIndex:"),
             .{ self.buf_cells.value, @as(c_ulong, 0), @as(c_ulong, 0) },
         );
+        encoder.msgSend(
+            void,
+            objc.sel("setVertexBytes:length:atIndex:"),
+            .{
+                @ptrCast(*const anyopaque, &uniforms),
+                @as(c_ulong, @sizeOf(@TypeOf(uniforms))),
+                @as(c_ulong, 1),
+            },
+        );
 
         // Draw
         // encoder.msgSend(
diff --git a/src/shaders/cell.metal b/src/shaders/cell.metal
index 538018e04..53ffc995c 100644
--- a/src/shaders/cell.metal
+++ b/src/shaders/cell.metal
@@ -1,13 +1,19 @@
-vertex float4 basic_vertex(unsigned int vid [[ vertex_id ]]) {
+using namespace metal;
+
+struct Uniforms {
+    float4x4 projection_matrix;
+    float2 cell_size;
+};
+
+vertex float4 basic_vertex(
+  unsigned int vid [[ vertex_id ]],
+  constant Uniforms &uniforms [[ buffer(1) ]]
+) {
   // Where we are in the grid (x, y) where top-left is origin
   float2 grid_coord = float2(0.0f, 0.0f);
 
-  // The size of a single cell in pixels
-  //float2 cell_size = float2(75.0f, 100.0f);
-  float2 cell_size = float2(1.0f, 1.0f);
-
   // Convert the grid x,y into world space x, y by accounting for cell size
-  float2 cell_pos = cell_size * grid_coord;
+  float2 cell_pos = uniforms.cell_size * grid_coord;
 
   // Turn the cell position into a vertex point depending on the
   // vertex ID. Since we use instanced drawing, we have 4 vertices
@@ -26,9 +32,9 @@ vertex float4 basic_vertex(unsigned int vid [[ vertex_id ]]) {
   // Calculate the final position of our cell in world space.
   // We have to add our cell size since our vertices are offset
   // one cell up and to the left. (Do the math to verify yourself)
-  cell_pos = cell_pos + cell_size * position;
+  cell_pos = cell_pos + uniforms.cell_size * position;
 
-  return float4(cell_pos.x, cell_pos.y, 0.0f, 1.0f);
+  return uniforms.projection_matrix * float4(cell_pos.x, cell_pos.y, 0.0f, 1.0f);
 }
 
 fragment half4 basic_fragment() {