creates an extruded pentagon VBO with indexing and VAO

gistfile1.cpp

void CreatePentagon() {
  float step = 2.0*M_PI/5, t=0;
	Vertex Vertices[7+7+12];
	// pentagon[0] = vec3(0);
	// bottom
	vec4 color(1,0,0,1);
	Vertices[0].normal = vec3(0,-1,0);
	Vertices[0].color = color;
	for (int i=1; i<7; i++, t-=step) {
		Vertices[i].pos = vec3(cosf(t),0,sinf(t));
		Vertices[i].color = color;
		Vertices[i].normal = vec3(0,-1,0);
	}
	color = vec4(0,1,0,1);
	// top
	for (int i=7; i<14; i++) {
		Vertices[i].pos = Vertices[(7+(7-i))%7].pos + vec3(0,1,0);
		Vertices[i].color = color;
		Vertices[i].normal = vec3(0,1,0);
	}
	color = vec4(0,0,1,1);
	// walls
	for (int i=14; i<26; i+=2, t+=step) {
		Vertices[i+1].pos = vec3(cosf(t), 0, sinf(t));
		Vertices[i+1].color = color;
		Vertices[i+1].normal = Vertices[i].pos;
		Vertices[i].pos = vec3(cosf(t), 1, sinf(t));
		Vertices[i].color = color;
		Vertices[i].normal = Vertices[i].pos; // yes, cause it must be normalized
	}
	// convert to this silly orientation, you can remove this (just for the assignment)
	for (int i=0; i<26; i++) {
		float t = Vertices[i].pos.y;
		Vertices[i].pos.y = Vertices[i].pos.z;
		Vertices[i].pos.z = t;
		t = Vertices[i].normal.y;
		Vertices[i].normal.y = Vertices[i].normal.x;
		Vertices[i].normal.x = t;
	}
	GLushort Indices[] = {
		0,1,2,
		0,2,3,
		0,3,4,
		0,4,5,
		0,5,6, // bottom done
		7,8,9,
		7,9,10,
		7,10,11,
		7,11,12,
		7,12,13, // top done
		14,15,16, // walls start
		15,17,16,
		16,17,18,
		17,19,18,
		18,19,20,
		19,21,20,
		20,21,22,
		21,23,22,
		22,23,24,
		23,25,24,
		25,0,1
	};
	// Create Vertex Array Object
	genVAO(1, &VaoId[VAO_PENT]);
	bindVAO(VaoId[VAO_PENT]);
	
	// Create Buffer for vertex data
	glGenBuffers(1, &BufferId[BUF_PENT_VERTS]);
	glBindBuffer(GL_ARRAY_BUFFER, BufferId[BUF_PENT_VERTS]);
	glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);

	// Assign vertex attributes
	glVertexAttribPointer(rootNode.shader.in_Position, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0);
	glVertexAttribPointer(rootNode.shader.in_Color, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)myOffset(Vertex,color));
	if (rootNode.shader.in_Normal != -1) {
	    glVertexAttribPointer(rootNode.shader.in_Normal, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (void*)myOffset(Vertex,normal));
	    glEnableVertexAttribArray(rootNode.shader.in_Normal);
	}

	glEnableVertexAttribArray(rootNode.shader.in_Position);
	glEnableVertexAttribArray(rootNode.shader.in_Color);
	
	// Vreate Buffer for indics
	glGenBuffers(1, &BufferId[BUF_PENT_IDX]);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, BufferId[BUF_PENT_IDX]);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(Indices), Indices, GL_STATIC_DRAW);

	GLenum ErrorCheckValue = glGetError();
	if (ErrorCheckValue != GL_NO_ERROR) {
		fprintf(stderr,"ERROR: Could not create a VBO (%d): %s \n", __LINE__, gluErrorString(ErrorCheckValue));
		exit(-1);
	}

    bindVAO(0);
}