1 files changed, 50 insertions, 8 deletions

diff --git a/src/main.zig b/src/main.zig
index 6d119af..6c2b0c4 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,14 +1,16 @@
 const std = @import("std");
+const fs = @import("std").fs;
 const panic = std.debug.panic;
 const c = @import("c.zig");
 const debug_gl = @import("debug_gl.zig");
 const cfg = @import("config.zig");
 const out = @import("output.zig");
 const gl = @import("gl.zig");
+const c_allocator = @import("std").heap.c_allocator;
 
 var window: *c.GLFWwindow = undefined;
 
-fn errorCallback(err: c_int, description: [*c]const u8) callconv(.C) void {
+extern fn errorCallback(err: c_int, description: [*c]const u8) callconv(.C) void {
     panic("Error: {}\n", .{description});
 }
 
@@ -23,6 +25,12 @@ pub fn main() !void {
     }
     defer c.glfwTerminate();
 
+    var monitor_count: c_int = 0;
+    const monitors = c.glfwGetMonitors(&monitor_count);
+    for (monitors[0..@intCast(usize, monitor_count)]) |monitor, i| {
+        std.debug.warn("monitor {}: '{s}'\n", .{ i, @ptrCast([*:0]const u8, c.glfwGetMonitorName(monitor))});
+    }
+
     c.glfwWindowHint(c.GLFW_CONTEXT_VERSION_MAJOR, 4);
     c.glfwWindowHint(c.GLFW_CONTEXT_VERSION_MINOR, 2);
     c.glfwWindowHint(c.GLFW_OPENGL_FORWARD_COMPAT, c.GL_TRUE);
@@ -64,7 +72,7 @@ pub fn main() !void {
 
     debug_gl.assertNoError();
 
-    var redShader = try gl.ShaderProgram.create(
+    var main_program = try gl.ShaderProgram.create(
         \\#version 330 core
         \\
         \\layout(location = 0) in vec2 position;
@@ -83,12 +91,14 @@ pub fn main() !void {
         \\uniform float offset;
         \\
         \\void main() {
-        \\  color = vec4(mod(uv + offset, vec2(1)), 0, 1);
+        \\  color = vec4(offset,0,0,1); // mod(uv + offset, vec2(1)), 0, 1);
         \\}
-    ,
-        null
     );
-    defer redShader.destroy();
+    defer main_program.destroy();
+
+    const shader_file = try fs.cwd().openFile(config.fragment, .{});
+    var last_stat = try shader_file.stat();
+    try reloadShader(&main_program, shader_file, last_stat.size);
 
     var fbo = try gl.FramebufferObject.create(config.width, config.height);
     defer fbo.destroy();
@@ -103,12 +113,18 @@ pub fn main() !void {
         const elapsed = now_time - prev_time;
         prev_time = now_time;
 
+        const stat = try shader_file.stat();
+        if (stat.mtime > last_stat.mtime) {
+            try reloadShader(&main_program, shader_file, stat.size);
+            last_stat = stat;
+        }
+
         fbo.bind();
         c.glClear(c.GL_COLOR_BUFFER_BIT);
         
-        redShader.bind();
+        main_program.bind();
         offset += @floatCast(f32, elapsed / 4);
-        redShader.setUniformFloat(redShader.uniformLocation("offset"), offset);
+        main_program.setUniformFloat(main_program.uniformLocation("offset"), offset);
         constants.normalizedQuad.draw();
         fbo.unbind();
         
@@ -129,3 +145,29 @@ pub fn main() !void {
 
     debug_gl.assertNoError();
 }
+
+fn reloadShader(current: *gl.ShaderProgram, frag_file: fs.File, size: u64) !void {
+    var frag_source = try c_allocator.alloc(u8, @intCast(usize, size));
+    defer c_allocator.free(frag_source);
+    try frag_file.seekTo(0);
+    const length = try frag_file.read(frag_source);
+
+    const vert_source =
+        \\#version 330 core
+        \\
+        \\layout(location = 0) in vec2 position;
+        \\out vec2 uv;
+        \\
+        \\void main() {
+        \\  uv = position / 2.0 + 0.5;
+        \\  gl_Position = vec4(position, 0, 1);
+        \\}
+    ;
+    
+    if (gl.ShaderProgram.create(vert_source, frag_source[0..length])) |new_program| {
+        current.destroy();
+        current.* = new_program;
+    } else |err| {
+        std.debug.warn("Error while reloading shader:{}\n", .{ err });
+    }
+}