From c7575fc330a5b5d5367938593df37820c8241995 Mon Sep 17 00:00:00 2001
From: archibate <17721388340@163.com>
Date: Tue, 25 Feb 2020 17:23:41 +0800
Subject: [PATCH] [skip ci] glsl raw_mod fixed

---
 taichi/backends/codegen_opengl.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/taichi/backends/codegen_opengl.cpp b/taichi/backends/codegen_opengl.cpp
index 803eac2b70017..7e71e98510578 100644
--- a/taichi/backends/codegen_opengl.cpp
+++ b/taichi/backends/codegen_opengl.cpp
@@ -479,6 +479,11 @@ int _rand_i32()\n\
       emit("{} {} = {}(floor((float({}) * (1 + sign({} * {}) * 1e-6)) / float({})));",
           dt_name, bin_name, dt_name, lhs_name, lhs_name, rhs_name, rhs_name);
       return;
+    } else if (bin->op_type == BinaryOpType::mod) {
+      // NOTE: the GLSL built-in function `mod()` is a pythonic mod: x - y * floor(x / y)
+      emit("{} {} = {} - {} * int({} / {});", dt_name, bin_name, lhs_name, rhs_name,
+          lhs_name, rhs_name);
+      return;
     }
     const auto binop = binary_op_type_symbol(bin->op_type);
     if (is_opengl_binary_op_infix(bin->op_type)) {