1 Course no: CpSc6050-001 

2 Name:Qingbo Lai

3 Brief solution description:
	  *First, Read the pyramid.obj file into an array vpack.
	  *Secondly, use 2-pass render method. render the object with shader objects [passthru.vert, passthru.frag], and then render the normals with [normals.vert, normals.geom, normals.frag]
4 Lessons learned:
	【1】 avoiding some typo in shader file，There's no hint when compile, but some error infomation appear when run ./hello .
		tarus@ubuntu:/mnt/hgfs/10SrcFldr/CPSC6050CG/asg5/asg05_03$ ./hello
		ERROR::SHADER::VERTEX::COMPILATION_FAILED
		0:7(1): error: syntax error, unexpected OUT_TOK, expecting ',' or ';'
		ERROR::SHADER::PROGRAM::LINkED_FAILED.
		error: linking with uncompiled/unspecialized shader
	========================

	【2】putting this statment - glDeleteProgram(programID); - into the do-while loop, leading to can't display the normal。


	【3】when defined outside the do-while loop, m & view must be initialized to 1.0f.
	        glm::mat4 view;
	        view = glm::mat4(1.0f);
	        view = glm::translate(view, glm::vec3(0.0f, 0.0f, -4.0f));

	        glm::mat4 m；
	        m=glm::mat4(1.0f);
	        m=glm::rotate(m,(float)glfwGetTime()*2,glm::vec3(0.5f, 1.0f, 0.0f));      

	【4】Define a flag_fn variable in CalcNormalsin function of obj_loader.cpp file to avoid adding the same normal twice . By check the dot product value to achieve this purpose.
	    //use flag_fn to identify if this vector already exist.
        int flag_fn = 1;
        for (int g = 0; g < f; g++) {
          float dot_result = face_normals_[face_indices_[v][f]].x * face_normals_[face_indices_[v][g]].x \
                             + face_normals_[face_indices_[v][f]].y * face_normals_[face_indices_[v][g]].y \
                             + face_normals_[face_indices_[v][f]].z * face_normals_[face_indices_[v][g]].z; 
          float modulus_vf = face_normals_[face_indices_[v][f]].x * face_normals_[face_indices_[v][f]].x \
                             + face_normals_[face_indices_[v][f]].y * face_normals_[face_indices_[v][f]].y \
                             + face_normals_[face_indices_[v][f]].z * face_normals_[face_indices_[v][f]].z;
          float modulus_vg = face_normals_[face_indices_[v][g]].x * face_normals_[face_indices_[v][g]].x \
                             + face_normals_[face_indices_[v][g]].y * face_normals_[face_indices_[v][g]].y \
                             + face_normals_[face_indices_[v][g]].z * face_normals_[face_indices_[v][g]].z;
          float modulus_fg = sqrt(modulus_vf * modulus_vg);
          if (dot_result == modulus_fg) {
            flag_fn = 0;
            break;
          }


5 Special usage instructions:
  *Platform: ubuntu16.04
	  $make
	  $./hello
  *using esc key to close the window.