Added bi-linear interpolation for getting Z coordinate at any location in the grid.

render.cpp

@@ -508,6 +508,7 @@ std::string get_shader_info_log(GLuint id) {
     char error_log[log_length]; // length includes the NULL character
     glGetShaderInfoLog(id, log_length, &log_length, &error_log[0]);
 
+
     return std::string(error_log, log_length);
 }
 
@@ -521,7 +522,6 @@ std::string get_program_info_log(GLuint id) {
     return {error_log, (size_t) log_length};
 }
 
-
 bool check_compile_error(GLuint shader_id) {
     GLint is_compiled = 0;
     glGetShaderiv(shader_id, GL_COMPILE_STATUS, &is_compiled);