opengl: extract into folder

src/opengl/Program.zig

@@ -0,0 +1,60 @@
+const Program = @This();
+
+const std = @import("std");
+const assert = std.debug.assert;
+const log = std.log.scoped(.opengl);
+
+const c = @import("c.zig");
+const Shader = @import("Shader.zig");
+const errors = @import("errors.zig");
+
+id: c.GLuint,
+
+pub fn create() !Program {
+    const id = c.glCreateProgram();
+    if (id == 0) try errors.mustError();
+
+    log.debug("program created id={}", .{id});
+    return Program{ .id = id };
+}
+
+pub fn attachShader(p: Program, s: Shader) !void {
+    c.glAttachShader(p.id, s.id);
+    try errors.getError();
+}
+
+pub fn link(p: Program) !void {
+    c.glLinkProgram(p.id);
+
+    // Check if linking succeeded
+    var success: c_int = undefined;
+    c.glGetProgramiv(p.id, c.GL_LINK_STATUS, &success);
+    if (success == c.GL_TRUE) {
+        log.debug("program linked id={}", .{p.id});
+        return;
+    }
+
+    log.err("program link failure id={} message={s}", .{
+        p.id,
+        std.mem.sliceTo(&p.getInfoLog(), 0),
+    });
+    return error.CompileFailed;
+}
+
+/// getInfoLog returns the info log for this program. This attempts to
+/// keep the log fully stack allocated and is therefore limited to a max
+/// amount of elements.
+//
+// NOTE(mitchellh): we can add a dynamic version that uses an allocator
+// if we ever need it.
+pub fn getInfoLog(s: Program) [512]u8 {
+    var msg: [512]u8 = undefined;
+    c.glGetProgramInfoLog(s.id, msg.len, null, &msg);
+    return msg;
+}
+
+pub fn destroy(p: Program) void {
+    assert(p.id != 0);
+    c.glDeleteProgram(p.id);
+    log.debug("program destroyed id={}", .{p.id});
+}