From 46dd084ee9ba47997ed1f895fc2b0fc7bf39c480 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Fri, 17 Nov 2023 08:27:06 -0800
Subject: [PATCH] renderer/opengl: wip

---
 src/renderer/OpenGL.zig            | 33 +++++++++++++++++++++++++++---
 src/renderer/shaders/custom.v.glsl |  7 +++++++
 src/renderer/shadertoy.zig         |  7 ++++---
 3 files changed, 41 insertions(+), 6 deletions(-)
 create mode 100644 src/renderer/shaders/custom.v.glsl

diff --git a/src/renderer/OpenGL.zig b/src/renderer/OpenGL.zig
index ce442ed48..7d91cc9a9 100644
--- a/src/renderer/OpenGL.zig
+++ b/src/renderer/OpenGL.zig
@@ -8,6 +8,7 @@ const assert = std.debug.assert;
 const testing = std.testing;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
+const shadertoy = @import("shadertoy.zig");
 const apprt = @import("../apprt.zig");
 const configpkg = @import("../config.zig");
 const font = @import("../font/main.zig");
@@ -320,7 +321,7 @@ pub fn init(alloc: Allocator, options: renderer.Options) !OpenGL {
         options.config.font_thicken,
     );
 
-    var gl_state = try GLState.init(options.font_group);
+    var gl_state = try GLState.init(alloc, options.config, options.font_group);
     errdefer gl_state.deinit();
 
     return OpenGL{
@@ -439,7 +440,7 @@ pub fn displayRealize(self: *OpenGL) !void {
     );
 
     // Make our new state
-    var gl_state = try GLState.init(self.font_group);
+    var gl_state = try GLState.init(self.alloc, self.config, self.font_group);
     errdefer gl_state.deinit();
 
     // Unrealize if we have to
@@ -1579,7 +1580,33 @@ const GLState = struct {
     texture: gl.Texture,
     texture_color: gl.Texture,
 
-    pub fn init(font_group: *font.GroupCache) !GLState {
+    pub fn init(
+        alloc: Allocator,
+        config: DerivedConfig,
+        font_group: *font.GroupCache,
+    ) !GLState {
+        var arena = ArenaAllocator.init(alloc);
+        defer arena.deinit();
+        const arena_alloc = arena.allocator();
+
+        // Load our custom shaders
+        const custom_shaders: []const [:0]const u8 = shadertoy.loadFromFiles(
+            arena_alloc,
+            config.custom_shaders.items,
+            .glsl,
+        ) catch |err| err: {
+            log.warn("error loading custom shaders err={}", .{err});
+            break :err &.{};
+        };
+
+        if (custom_shaders.len > 0) {
+            const cp = try gl.Program.createVF(
+                @embedFile("shaders/custom.v.glsl"),
+                custom_shaders[0],
+            );
+            _ = cp;
+        }
+
         // Blending for text. We use GL_ONE here because we should be using
         // premultiplied alpha for all our colors in our fragment shaders.
         // This avoids having a blurry border where transparency is expected on
diff --git a/src/renderer/shaders/custom.v.glsl b/src/renderer/shaders/custom.v.glsl
new file mode 100644
index 000000000..ff6f60541
--- /dev/null
+++ b/src/renderer/shaders/custom.v.glsl
@@ -0,0 +1,7 @@
+#version 330 core
+
+layout (location = 0) in vec2 position;
+
+void main(){
+    gl_Position = vec4(position.x, position.y, 0.0f, 1.0f);
+}
diff --git a/src/renderer/shadertoy.zig b/src/renderer/shadertoy.zig
index 92b340e76..90541fda9 100644
--- a/src/renderer/shadertoy.zig
+++ b/src/renderer/shadertoy.zig
@@ -9,7 +9,7 @@ const spvcross = @import("spirv_cross");
 const log = std.log.scoped(.shadertoy);
 
 /// The target to load shaders for.
-pub const Target = enum { msl };
+pub const Target = enum { glsl, msl };
 
 /// Load a set of shaders from files and convert them to the target
 /// format. The shader order is preserved.
@@ -87,6 +87,7 @@ pub fn loadFromFile(
     return switch (target) {
         // Important: using the alloc_gpa here on purpose because this
         // is the final result that will be returned to the caller.
+        .glsl => try glslFromSpv(alloc_gpa, spirv),
         .msl => try mslFromSpv(alloc_gpa, spirv),
     };
 }
@@ -203,7 +204,7 @@ pub fn glslFromSpv(alloc: Allocator, spv: []const u8) ![:0]const u8 {
             if (c.spvc_compiler_options_set_uint(
                 options,
                 c.SPVC_COMPILER_OPTION_GLSL_VERSION,
-                330,
+                430,
             ) != c.SPVC_SUCCESS) {
                 return error.SpvcFailed;
             }
@@ -349,7 +350,7 @@ test "shadertoy to glsl" {
     const glsl = try glslFromSpv(alloc, spvlist.items);
     defer alloc.free(glsl);
 
-    //log.warn("glsl={s}", .{glsl});
+    log.warn("glsl={s}", .{glsl});
 }
 
 const test_crt = @embedFile("shaders/test_shadertoy_crt.glsl");