From 07b47f3e82477da6d4539dfe8023a4088e06b7c4 Mon Sep 17 00:00:00 2001
From: Dendy <dendy@fai.st>
Date: Fri, 22 Jul 2022 16:10:58 +0200
Subject: [PATCH] Basic shaders for triangle coloring

---
 src/main.zig            | 47 +++++++++++++++++++++++++----------------
 src/shaders/fragment.fs |  7 ++++++
 src/shaders/vector.vs   |  8 +++++++
 3 files changed, 44 insertions(+), 18 deletions(-)
 create mode 100644 src/shaders/fragment.fs
 create mode 100644 src/shaders/vector.vs

diff --git a/src/main.zig b/src/main.zig
index 5ae2fc0..c9d9253 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -11,8 +11,9 @@ pub fn main() !void {
     try sdl.init(.{ .video = true, .audio = true, .events = true });
     defer sdl.quit();
 
-    try sdl.gl.setAttribute(.{ .context_major_version = 2 });
-    try sdl.gl.setAttribute(.{ .context_minor_version = 1 });
+    // Set OpenGL version
+    try sdl.gl.setAttribute(.{ .context_major_version = 3 });
+    try sdl.gl.setAttribute(.{ .context_minor_version = 3 });
 
     const window = try sdl.createWindow(
         "USG",
@@ -27,6 +28,24 @@ pub fn main() !void {
     const ctx = try sdl.gl.createContext(window);
     defer sdl.gl.deleteContext(ctx);
 
+    const program = gl.Program.create();
+    {
+        const vs = gl.Shader.create(.vertex);
+        defer vs.delete();
+        vs.source(1, &.{@embedFile("shaders/vector.vs")});
+        vs.compile();
+        const fs = gl.Shader.create(.fragment);
+        defer fs.delete();
+        fs.source(1, &.{@embedFile("shaders/fragment.fs")});
+        fs.compile();
+        program.attach(vs);
+        defer program.detach(vs);
+        program.attach(fs);
+        defer program.detach(fs);
+        program.link();
+    }
+    program.use();
+
     var vertex_array = gl.VertexArray.gen();
     vertex_array.bind();
 
@@ -36,9 +55,9 @@ pub fn main() !void {
         0.0, 1.0, 0.0,
     };
 
-    const buffer = gl.Buffer.gen();
-    buffer.bind(.array_buffer);
-    buffer.data(f32, &vertex_buffer, .static_draw);
+    const buf = gl.Buffer.gen();
+    buf.bind(.array_buffer);
+    buf.data(f32, &vertex_buffer, .static_draw);
 
     //var renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_PRESENTVSYNC | SDL.SDL_RENDERER_ACCELERATED) orelse return;
     //defer _ = SDL.SDL_DestroyRenderer(renderer);
@@ -48,9 +67,10 @@ pub fn main() !void {
 
     //var current_state: State = main_menu.state;
 
-    //_ = SDL.SDL_SetRenderDrawBlendMode(renderer, SDL.SDL_BLENDMODE_BLEND);
     //_ = SDL.IMG_Init(SDL.IMG_INIT_JPG);
 
+    gl.clearColor(0.91, 0.97, 1.00, 1.00);
+
     mainLoop: while (true) {
         while (sdl.pollEvent()) |ev| {
             switch (ev) {
@@ -59,29 +79,20 @@ pub fn main() !void {
             }
         }
 
-        gl.clear(.{});
+        gl.clear(.{ .color = true });
 
         gl.enableVertexAttribArray(0);
-        buffer.bind(.array_buffer);
+        buf.bind(.array_buffer);
 
         gl.vertexAttribPointer(0, 3, .float, false, 0, 0);
         gl.drawArrays(.triangles, 0, 3);
         gl.disableVertexAttribArray(0);
 
-        sdl.gl.swapWindow(window);
-
-        //_ = SDL.SDL_SetRenderDrawColor(renderer, 231, 247, 255, 0xFF);
-        //_ = SDL.SDL_RenderClear(renderer);
-
         //current_state = switch (current_state) {
             //.main_menu => main_menu.tick(),
             //.game => game.tick(),
         //};
 
-        //SDL.SDL_RenderPresent(renderer);
+        sdl.gl.swapWindow(window);
     }
 }
-
-fn initGL() void {
-
-}
diff --git a/src/shaders/fragment.fs b/src/shaders/fragment.fs
new file mode 100644
index 0000000..6e8915f
--- /dev/null
+++ b/src/shaders/fragment.fs
@@ -0,0 +1,7 @@
+#version 330 core
+
+out vec3 color;
+
+void main(){
+     color = vec3(1,0,0);
+}
diff --git a/src/shaders/vector.vs b/src/shaders/vector.vs
new file mode 100644
index 0000000..cb16d4d
--- /dev/null
+++ b/src/shaders/vector.vs
@@ -0,0 +1,8 @@
+#version 330 core
+
+layout(location = 0) in vec3 vertexPosition_modelspace;
+
+void main() {
+     gl_Position.xyz = vertexPosition_modelspace;
+     gl_Position.w = 1.0;
+}