diff --git a/examples/28-sdl-graphics.sx b/examples/28-sdl-graphics.sx
index e803a2a..6459a4d 100644
--- a/examples/28-sdl-graphics.sx
+++ b/examples/28-sdl-graphics.sx
@@ -131,49 +131,8 @@ main :: () {
     glEnable(GL_DEPTH_TEST);
     glDepthFunc(GL_LESS);
 
-    // Shaders
-    vert_src : [:0]u8 = #string glsl
-#version 330 core
-layout (location = 0) in vec3 aPos;
-layout (location = 1) in vec3 aNormal;
-uniform mat4 uMVP;  
-out vec3 vNormal;
-out vec3 vPos;
-
-void main() {
-    gl_Position = uMVP * vec4(aPos, 1.0);
-    vNormal = aNormal;
-    vPos = aPos;
-}
-glsl;
-
-    frag_src : [:0]u8 = #string GLSL
-#version 330 core
-in vec3 vNormal;
-in vec3 vPos;
-out vec4 FragColor;
-uniform vec3 uLightDir;
-uniform float uWire;
-void main() {
-    if (uWire > 0.5) {
-        FragColor = vec4(0.05, 0.05, 0.05, 1.0);
-        return;
-    }
-    vec3 n = normalize(vNormal);
-    vec3 l = normalize(uLightDir);
-    float diff = max(dot(n, l), 0.15);
-    float cx = floor(vPos.x * 2.0 + 0.001);
-    float cy = floor(vPos.y * 2.0 + 0.001);
-    float cz = floor(vPos.z * 2.0 + 0.001);
-    float check = mod(cx + cy + cz, 2.0);
-    vec3 col1 = vec3(0.9, 0.5, 0.2);
-    vec3 col2 = vec3(0.2, 0.6, 0.9);
-    vec3 base = mix(col1, col2, check);
-    FragColor = vec4(base * diff, 1.0);
-}
-GLSL;
-
-    program := create_program(vert_src, frag_src);
+    print("create program: {}\n{}\n", VERT_SHADER_SRC, FRAG_SHADER_SRC);
+    program := create_program(VERT_SHADER_SRC, FRAG_SHADER_SRC);
     glUseProgram(program);
 
     mvp_loc : s32 = glGetUniformLocation(program, "uMVP");
@@ -317,3 +276,44 @@ GLSL;
     SDL_DestroyWindow(window);
     SDL_Quit();
 }
+
+VERT_SHADER_SRC : string = #string GLSL
+#version 330 core
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec3 aNormal;
+uniform mat4 uMVP;  
+out vec3 vNormal;
+out vec3 vPos;
+
+void main() {
+    gl_Position = uMVP * vec4(aPos, 1.0);
+    vNormal = aNormal;
+    vPos = aPos;
+}
+GLSL;
+
+FRAG_SHADER_SRC : string = #string GLSL
+#version 330 core
+in vec3 vNormal;
+in vec3 vPos;
+out vec4 FragColor;
+uniform vec3 uLightDir;
+uniform float uWire;
+void main() {
+    if (uWire > 0.5) {
+        FragColor = vec4(0.05, 0.05, 0.05, 1.0);
+        return;
+    }
+    vec3 n = normalize(vNormal);
+    vec3 l = normalize(uLightDir);
+    float diff = max(dot(n, l), 0.15);
+    float cx = floor(vPos.x * 2.0 + 0.001);
+    float cy = floor(vPos.y * 2.0 + 0.001);
+    float cz = floor(vPos.z * 2.0 + 0.001);
+    float check = mod(cx + cy + cz, 2.0);
+    vec3 col1 = vec3(0.9, 0.5, 0.2);
+    vec3 col2 = vec3(0.2, 0.6, 0.9);
+    vec3 base = mix(col1, col2, check);
+    FragColor = vec4(base * diff, 1.0);
+}
+GLSL;
\ No newline at end of file
diff --git a/src/codegen.zig b/src/codegen.zig
index 5222033..5e0efae 100644
--- a/src/codegen.zig
+++ b/src/codegen.zig
@@ -2349,10 +2349,47 @@ pub const CodeGen = struct {
             .bool_literal => |lit| {
                 return c.LLVMConstInt(llvm_ty, if (lit.value) 1 else 0, 0);
             },
+            .string_literal => |sl| {
+                const content = if (sl.is_raw) sl.raw else (unescape.unescapeString(self.allocator, sl.raw) catch return null);
+                return self.buildConstStrGlobal(content);
+            },
+            .struct_literal => |sl| {
+                return self.evalConstantStruct(sl, target_ty);
+            },
             else => return null,
         }
     }
 
+    /// Evaluate a struct literal as a constant (for global initializers).
+    fn evalConstantStruct(self: *CodeGen, sl: ast.StructLiteral, target_ty: Type) ?c.LLVMValueRef {
+        const struct_name = sl.struct_name orelse target_ty.struct_type;
+        const info = self.lookupStructInfo(struct_name) orelse return null;
+
+        if (info.field_names.len > 32) return null;
+        var field_vals: [32]c.LLVMValueRef = undefined;
+        const n = info.field_names.len;
+
+        // Initialize with undef for each field
+        for (0..n) |i| {
+            field_vals[i] = c.LLVMGetUndef(self.typeToLLVM(info.field_types[i]));
+        }
+
+        // Fill in provided field values
+        for (sl.field_inits) |fi| {
+            const field_name = fi.name orelse continue; // skip positional for now
+            const idx = blk: {
+                for (info.field_names, 0..) |fn_name, j| {
+                    if (std.mem.eql(u8, fn_name, field_name)) break :blk j;
+                }
+                return null; // unknown field
+            };
+            const val = self.evalConstant(fi.value, info.field_types[idx]) orelse return null;
+            field_vals[idx] = val;
+        }
+
+        return c.LLVMConstNamedStruct(info.llvm_type, @ptrCast(&field_vals), @intCast(n));
+    }
+
     /// Register a top-level value constant (e.g., `SPECIAL_VALUE :u8: 42;`) as an LLVM global.
     fn registerTopLevelConstant(self: *CodeGen, cd: ast.ConstDecl) !void {
         const ta = cd.type_annotation orelse return; // need explicit type for top-level constants
@@ -2382,9 +2419,24 @@ pub const CodeGen = struct {
         const llvm_ty = self.typeToLLVM(sx_ty);
         const name_z = try self.allocator.dupeZ(u8, vd.name);
         const global = c.LLVMAddGlobal(self.module, llvm_ty, name_z.ptr);
-        // Initialize with undef (will be set at runtime, e.g. by load_gl)
+
+        // Try constant-evaluable initializer → register as comptime_global for JIT compatibility
+        if (vd.value) |val_node| {
+            if (self.evalConstant(val_node, sx_ty)) |const_val| {
+                c.LLVMSetInitializer(global, const_val);
+                c.LLVMSetGlobalConstant(global, 1);
+                try self.comptime_globals.put(vd.name, .{
+                    .global = global,
+                    .ty = sx_ty,
+                    .expr = val_node,
+                    .is_resolved = true,
+                });
+                return;
+            }
+        }
+
+        // Non-constant globals: mutable, initialized with undef (set at runtime, e.g. by load_gl)
         c.LLVMSetInitializer(global, self.getUndef(llvm_ty));
-        // NOT constant — this is a mutable global
         c.LLVMSetGlobalConstant(global, 0);
 
         try self.global_mutable_vars.put(vd.name, .{ .ptr = global, .ty = sx_ty });