From 5e766ab9c6a84c0de5fc9142edd5fdbe8437da3a Mon Sep 17 00:00:00 2001
From: IntegratedQuantum <jahe788@gmail.com>
Date: Sun, 28 Aug 2022 09:54:00 +0200
Subject: [PATCH] Add shader compilation and use reflection to assign uniform
 locations.

---
 src/graphics.zig | 94 ++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.zig     | 13 ++++++-
 2 files changed, 106 insertions(+), 1 deletion(-)
 create mode 100644 src/graphics.zig

diff --git a/src/graphics.zig b/src/graphics.zig
new file mode 100644
index 00000000..dc1ef240
--- /dev/null
+++ b/src/graphics.zig
@@ -0,0 +1,94 @@
+/// A collection of things that should make dealing with opengl easier.
+/// Also contains some basic 2d drawing stuff.
+
+const std = @import("std");
+
+const Allocator = std.mem.Allocator;
+
+const c = @cImport ({
+	@cInclude("glad/glad.h");
+});
+
+fn fileToString(allocator: Allocator, path: []const u8) ![]u8 {
+	const file = try std.fs.cwd().openFile(path, .{});
+	return file.readToEndAlloc(allocator, std.math.maxInt(usize));
+}
+
+pub fn init() void {
+
+}
+
+pub fn deinit() void {
+
+}
+
+pub const Shader = struct {
+	id: c_uint,
+	
+	fn addShader(self: *const Shader, filename: []const u8, shader_stage: c_uint) !void {
+		const source = try fileToString(std.heap.page_allocator, filename);
+		defer std.heap.page_allocator.free(source);
+		const ref_buffer = [_] [*c]u8 {@ptrCast([*c]u8, source.ptr)};
+		const shader = c.glCreateShader(shader_stage);
+		defer c.glDeleteShader(shader);
+		
+		var sourceLen: c_int = @intCast(c_int, source.len);
+		c.glShaderSource(shader, 1, @ptrCast([*c]const [*c]const u8, &ref_buffer[0]), &sourceLen);
+		
+		c.glCompileShader(shader);
+
+		var success: c_int = undefined;
+		c.glGetShaderiv(shader, c.GL_COMPILE_STATUS, &success);
+		if(success != c.GL_TRUE) {
+			var len: u32 = undefined;
+			c.glGetShaderiv(shader, c.GL_INFO_LOG_LENGTH, @ptrCast(*c_int, &len));
+			var buf: [4096] u8 = undefined;
+			c.glGetShaderInfoLog(shader, 4096, @ptrCast(*c_int, &len), &buf);
+			std.log.err("Error compiling shader {s}:\n{s}\n", .{filename, buf[0..len]});
+			return error.FailedCompiling;
+		}
+
+		c.glAttachShader(self.id, shader);
+	}
+
+	fn link(self: *const Shader) !void {
+		c.glLinkProgram(self.id);
+
+		var success: c_int = undefined;
+		c.glGetProgramiv(self.id, c.GL_LINK_STATUS, &success);
+		if(success != c.GL_TRUE) {
+			var len: u32 = undefined;
+			c.glGetProgramiv(self.id, c.GL_INFO_LOG_LENGTH, @ptrCast(*c_int, &len));
+			var buf: [4096] u8 = undefined;
+			c.glGetProgramInfoLog(self.id, 4096, @ptrCast(*c_int, &len), &buf);
+			std.log.err("Error Linking Shader program:\n{s}\n", .{buf[0..len]});
+			return error.FailedLinking;
+		}
+	} 
+	
+	pub fn create(vertex: []const u8, fragment: []const u8) !Shader {
+		var shader = Shader{.id = c.glCreateProgram()};
+		try shader.addShader(vertex, c.GL_VERTEX_SHADER);
+		try shader.addShader(fragment, c.GL_FRAGMENT_SHADER);
+		try shader.link();
+		return shader;
+	}
+
+	pub fn bulkGetUniformLocation(self: *const Shader, comptime T: type) T {
+		var ret: T = undefined;
+		inline for(@typeInfo(T).Struct.fields) |field| {
+			if(field.field_type == c_int) {
+				@field(ret, field.name) = c.glGetUniformLocation(self.id, field.name[0..]);
+			}
+		}
+		return ret;
+	}
+
+	pub fn bind(self: *const Shader) void {
+		c.glUseProgram(self.id);
+	}
+
+	pub fn delete(self: *const Shader) void {
+		c.glDeleteProgram(self.id);
+	}
+};
\ No newline at end of file
diff --git a/src/main.zig b/src/main.zig
index 427864fc..00628a92 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1,5 +1,7 @@
 const std = @import("std");
 
+const graphics = @import("graphics.zig");
+
 pub const c = @cImport ({
 	@cInclude("glad/glad.h");
 	@cInclude("GLFW/glfw3.h");
@@ -99,7 +101,7 @@ pub const Window = struct {
 				return;
 			}
 			const vidMode = c.glfwGetVideoMode(monitor).?;
-			c.glfwSetWindowMonitor(window, monitor, 0, 0, vidMode.width, vidMode.height, c.GLFW_DONT_CARE);
+			c.glfwSetWindowMonitor(window, monitor, 0, 0, vidMode[0].width, vidMode[0].height, c.GLFW_DONT_CARE);
 		} else {
 			c.glfwSetWindowMonitor(window, null, oldX, oldY, oldWidth, oldHeight, c.GLFW_DONT_CARE);
 			c.glfwSetWindowAttrib(window, c.GLFW_DECORATED, c.GLFW_TRUE);
@@ -115,7 +117,16 @@ pub fn main() !void {
 	try Window.init();
 	defer Window.deinit();
 
+	graphics.init();
+	defer graphics.deinit();
+
 	while(c.glfwWindowShouldClose(Window.window) == 0) {
+		{ // Check opengl errors:
+			const err = c.glGetError();
+			if(err != 0) {
+				std.log.err("Got opengl error: {}", .{err});
+			}
+		}
 		c.glfwSwapBuffers(Window.window);
 		c.glfwPollEvents();
 		c.glViewport(0, 0, Window.width, Window.height);