OpenGL program refuses to enter "for" loop

[Aideux]

Hey all! I've been getting this issue when I'm trying to check for collision against the camera in my game and boxes I've created. For some reason, however, the program refuses to enter the for loop that iterates through the game objects. I've been looking at the code for hours now and I really can't find the issue. Here's the "for" loop in question:

for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)
	{
		if ((*i)->getType() == ObjectType::BOX)
		{
			if (camera->getPosition().x >= ((*i)->Position.x - (*i)->getXBuffer()) && camera->getPosition().x <= ((*i)->Position.x + (*i)->getXBuffer()))
			{
				if (camera->getPosition().z >= ((*i)->Position.z - (*i)->getZBuffer()) && camera->getPosition().z <= ((*i)->Position.z + (*i)->getZBuffer()))		//change to Z axis and get camera position instead of radius
				{
					o++;
					cout << o << endl;
					collided = true;
				}
			}
		}
	}

and here's the main.cpp class. I don't think any or my other classes are effecting this issue:

#include "Font.h"
#include "ogro.h"
#include "Box.h"
#include "md2model.h"
#include "sstream"
#include "Camera.h"
#include "Time.h"
#include <vector>
using namespace std;

#include "vgl.h"
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtx/norm.hpp>
using namespace glm;
#define SPACEBAR_KEY 32
#define ESCAPE_KEY 033

Camera* camera;
Ogro* ogro;
//Box* boxes;
Font* font;
string fontText;
vector<GameObject*> gameObjects;
vector<Box * > boxes;
//vector<Box * > boxes;

int treesTapped = 0, points = 0;


float lastTime;
bool keyDown[255];

void timer(int value)
{
	glutPostRedisplay();
	glutTimerFunc(25, timer, 0);
}

void closeApp()
{
	delete camera;
	delete font;
	for (auto it = gameObjects.begin(); it != gameObjects.end(); ++it)
	{
		delete (*it);
	}	
}

void CheckKeyboard()
{
	int o = 0;

	if (keyDown['a'])
		camera->RotateLeft();
	if (keyDown['d'])
		camera->RotateRight();
	if (keyDown['w'])
		camera->MoveForward();
	if (keyDown['s'])
		camera->MoveBackWard();
	/*if (keyDown['e'])
		camera->StrafeRight();
	if (keyDown['q'])
		camera->StrafeLeft();*/

	vec3 p = camera->getPosition();
	camera->Update();
	bool collided = false;

	for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)
	{
		if ((*i)->getType() == ObjectType::BOX)
		{
			if (camera->getPosition().x >= ((*i)->Position.x - (*i)->getXBuffer()) && camera->getPosition().x <= ((*i)->Position.x + (*i)->getXBuffer()))
			{
				if (camera->getPosition().z >= ((*i)->Position.z - (*i)->getZBuffer()) && camera->getPosition().z <= ((*i)->Position.z + (*i)->getZBuffer()))		//change to Z axis and get camera position instead of radius
				{
					o++;
					cout << o << endl;
					collided = true;
				}
			}
		}
	}
	
	if (collided)
	{
		camera->position = p;
		camera->Update();
	}

	if (camera->position.x >= 90.0f)
	{
		camera->position.x = 90.0f;
	}
	if (camera->position.x <= -90.0f)
	{
		camera->position.x = -90.0f;
	}
	if (camera->position.z >= 90.0f)
	{
		camera->position.z = 90.0f;
	}
	if (camera->position.z <= -90.0f)
	{
		camera->position.z = -90.0f;
	}

	srand(time(NULL));

}

float getElapsedSeconds()
{
	float currentTime = float(GetTickCount()) / 1000.0f;
	float seconds = float(currentTime - lastTime);
	lastTime = currentTime;
	return seconds;
}

void keyboardUp(unsigned char key, int x, int y)
{
	keyDown[key] = false;
}

void mouseMovement(int x, int y)
{
	static bool warp = true;

	if (warp)
	{
		if (x>glutGet(GLUT_WINDOW_WIDTH) / 2)
			camera->RotateRight();
		else if (x<glutGet(GLUT_WINDOW_WIDTH) / 2)
			camera->RotateLeft();

		if (y>glutGet(GLUT_WINDOW_HEIGHT) / 2)
			camera->RotateUp();
		else if (y<glutGet(GLUT_WINDOW_HEIGHT) / 2)
			camera->RotateDown();

		glutWarpPointer(glutGet(GLUT_WINDOW_WIDTH) / 2, glutGet(GLUT_WINDOW_HEIGHT) / 2);
		warp = false;
	}
	else
		warp = true;
}

void mouseWheel(int button, int direction, int x, int y)
{

	if (button == 16)
		camera->ResetFOV();
	else if (direction > 0)
		camera->ZoomIn();
	else
		camera->ZoomOut();
}

void keyboardSpecialKeys(int key, int x, int y)
{
	float yaw;
	switch (key)
	{
	case GLUT_KEY_LEFT:
		yaw = ((Ogro*)gameObjects[1])->getYaw();
		yaw -= 5.0;
		((Ogro*)gameObjects[1])->setYaw(yaw);
		break;
	case GLUT_KEY_RIGHT:
		yaw = ((Ogro*)gameObjects[1])->getYaw();
		yaw += 5.0;
		((Ogro*)gameObjects[1])->setYaw(yaw);
		break;
	}
}

void keyboard(unsigned char key, int x, int y)
{
	keyDown[key] = true;
	switch (key)
	{
	case ESCAPE_KEY:
		exit(EXIT_SUCCESS);
		break;
	case 'e':
		((Box*)gameObjects[1])->ChangeTexture();
		treesTapped++;
		break;
	}
	
}

void display()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	CheckKeyboard();

	if (fontText.length() != 0)
		font->printText(fontText, 350, 550, 25);

	float dt = getElapsedSeconds();
	for (int i = 0; i <= gameObjects.size() - 1; i++)
	{
		switch (gameObjects[i]->getType())
		{
		case ObjectType::BOX:
			((Box*)gameObjects[i])->setMVPMatrix(camera->ViewMatrix, camera->ProjectionMatrix);
			gameObjects[i]->Draw(dt);
			break;
		/*case ObjectType::OGRO:
			((Ogro*)gameObjects[i])->changeInTime = dt;
			((Ogro*)gameObjects[i])->Draw(camera->ViewMatrix, camera->ProjectionMatrix);
			break;*/
		}
	}

	std::stringstream ss1;
	ss1 << "Trees tapped: " << treesTapped;
	font->printText(ss1.str().c_str(), 20, 550, 15);
	std::stringstream ss2;
	ss2 << "Points: " << points;
	font->printText(ss2.str().c_str(), 20, 520, 15);


	glutSwapBuffers();
}


void init()
{
	glClearColor(0.0f, 0.0f, 0.7f, 0.0f);
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);

	font = new Font();
	camera = new Camera();
	camera->setPosition(vec3(20.0f, 1.5f, 0.0f));
	glutWarpPointer(glutGet(GLUT_WINDOW_WIDTH) / 2, glutGet(GLUT_WINDOW_HEIGHT) / 2);
	std::fill(keyDown, keyDown + 255, false);

	gameObjects.push_back(new Box(vec3(0.0f, -2.0f, 0.0f), "data/images/grass-1.png", "data/shaders/Texture.vertexshader", "data/shaders/Texture.fragmentshader", "Data\\Models\\Floor.xml", true, 0.1f, vec3(100.0f, 0.1f, 100.0f), true));
	gameObjects.push_back(new Box(vec3(0.0f, -2.0f, 0.0f), "data/images/wood.bmp", "data/shaders/Texture.vertexshader", "data/shaders/Texture.fragmentshader", "Data\\Models\\Floor.xml", true, 0.1f, vec3(1.0f, 10.0f, 1.0f), true));
	gameObjects.push_back(new Box(vec3(0.0f, 6.0f, 0.0f), "data/images/leaves.jpg", "data/shaders/Texture.vertexshader", "data/shaders/Texture.fragmentshader", "Data\\Models\\Floor.xml", true, 0.1f, vec3(2.5f, 2.5f, 2.5f), true));

	/*gameObjects.push_back(new Ogro());
	((Ogro*)gameObjects[1])->Initialize();
	((Ogro*)gameObjects[1])->setPosition(vec3(0, 0, 0));
	((Ogro*)gameObjects[1])->setDirection(vec3(1, 0, 0));
	((Ogro*)gameObjects[1])->setYaw(90);

	gameObjects.push_back(new Ogro());
	((Ogro*)gameObjects[2])->Initialize();
	((Ogro*)gameObjects[2])->setYaw(-90);
	((Ogro*)gameObjects[2])->setPosition(vec3(0, 0, -3));
	((Ogro*)gameObjects[2])->setDirection(vec3(1, 0, 0));*/
}



int main(int argc, char** argv)
{
	glutInit(&argc, argv);

	glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH);
	glutInitWindowSize(1024, 768);
	glutInitContextProfile(GLUT_CORE_PROFILE);
	glutCreateWindow("Model Example1");
	

	if (glewInit())
	{
		cerr << "Unable to init glew" << endl;
		exit(EXIT_FAILURE);
	}

	init();
	glutDisplayFunc(display);
	glutKeyboardFunc(keyboard);
	glutKeyboardUpFunc(keyboardUp);
	glutSpecialFunc(keyboardSpecialKeys);
	//glutPassiveMotionFunc(mouseMovement);
	glutMouseWheelFunc(mouseWheel);
	glutTimerFunc(25, timer, 0);
	glutMainLoop();
	return 0;
}

[2kaud]

For some reason, however, the program refuses to enter the for loop that iterates through the game objects

for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)

Where are items added to the vector boxes - as this is not in the code posted? If the vector boxes has no elements then the for loop won't be entered.

[Aideux]

for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)

Where are items added to the vector boxes - as this is not in the code posted? If the vector boxes has no elements then the for loop won't be entered.

Did I not populate the vector in the Display function? I'm honestly so new to OpenGL and it seems more than a little foreign to me. If I did not, then how could I go about populating the vector so that I could achieve what I set out to do? Thank you so much, I really appreciate it!!

[2kaud]

Did I not populate the vector in the Display function?

It doesn't look like it.

I'm trying to check for collision against the camera in my game and boxes I've created

Also I don't see any code that actually creates boxes? Apart from the definition of the variable boxes and the for statement, no other posted code refers to boxes?

[Aideux]

It doesn't look like it.



Also I don't see any code that actually creates boxes? Apart from the definition of the variable boxes and the for statement, no other posted code refers to boxes?

There are two classes that are used to make boxes.

Box.cpp

#include "Box.h"



void Box::setPosition(vec3 position)
{
	Position = position;
	TranslationMatrix = translate(glm::mat4(1.0f), Position);
}


Box::Box(vec3 initialPosition, const char* imagePath, const string vertexShader, const string fragmentShader, char* modelPath, bool m, float sp, vec3 s, bool vis) :GameObject(vertexShader, fragmentShader)
{
	Position = initialPosition;
	vertexBufferData = VertexBufferData(modelPath);
	scaleVector = s;
	speed = sp/250;
	master = m;
	Visible = vis;
	radius = (s.x + s.y + s.z) / 3;

	direction = vec3(0.0f, 0.0f, 0.0f);
	Hit = false;
	rotationAngle = 0.0f;

	RotationMatrix = mat4(1.0f);
	OrbitMatrix = mat4(1.0f);
	ScaleMatrix = mat4(1.0f);

	ScaleMatrix = glm::scale(mat4(1.0f), scaleVector);
	TranslationMatrix = glm::translate(mat4(1.0f), Position);

	if (!shaderProgram->initialize())
	{
		std::cerr << "Could not initialize the shaders" << std::endl;
	}

	shaderProgram->bindShader();

	glGenVertexArrays(1, &vertexBufferData.VAO);
	glBindVertexArray(vertexBufferData.VAO);

	printf("Reading image %s\n", imagePath);
	int img_width, img_height, channels;
	unsigned char *img = SOIL_load_image(imagePath, &img_width, &img_height, &channels, 0);
	glGenTextures(1, &vertexBufferData.Texture);
	glBindTexture(GL_TEXTURE_2D, vertexBufferData.Texture);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img_width, img_height, 0, GL_RGB, GL_UNSIGNED_BYTE, img);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

	glGenBuffers(1, &vertexBufferData.elementBuffer);
	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vertexBufferData.elementBuffer);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, vertexBufferData.elementSize, &vertexBufferData.elements[0], GL_STATIC_DRAW);

	glGenBuffers(1, &vertexBufferData.vertexBuffer);
	glBindBuffer(GL_ARRAY_BUFFER, vertexBufferData.vertexBuffer);
	glBufferData(GL_ARRAY_BUFFER, vertexBufferData.verticiesSize, &vertexBufferData.verticies[0], GL_STATIC_DRAW);

	glGenBuffers(1, &vertexBufferData.textbuffer);
	glBindBuffer(GL_ARRAY_BUFFER, vertexBufferData.textbuffer);
	glBufferData(GL_ARRAY_BUFFER, vertexBufferData.texcoordSize, &vertexBufferData.texcoords[0], GL_STATIC_DRAW);
}


void Box::Draw(float deltaTime)
{
	if (Visible)
	{
		Position += direction * deltaTime * speed;
		shaderProgram->bindShader();
		glBindVertexArray(vertexBufferData.VAO);

		int size;
		glGetBufferParameteriv(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);

		glBindTexture(GL_TEXTURE_2D, vertexBufferData.Texture);
		shaderProgram->sendUniform("TextureSampler", 0);

		shaderProgram->sendUniform4x4("MVP", glm::value_ptr(MVP));

		glEnableVertexAttribArray(0);
		glEnableVertexAttribArray(1);

		glBindBuffer(GL_ARRAY_BUFFER, vertexBufferData.vertexBuffer);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));

		glBindBuffer(GL_ARRAY_BUFFER, vertexBufferData.textbuffer);
		glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, vertexBufferData.elementBuffer);

		glDrawElements(GL_TRIANGLES, size / sizeof(GLushort), GL_UNSIGNED_SHORT, 0);

		glDisableVertexAttribArray(0);
		glDisableVertexAttribArray(1);
	}
	
}


void Box::OnCollide(Box *box)
{
	if (master)//you are the master cube
	{
		/*We do nothing if we are the master cube*/
		return;
	}
	else if (box->master)//hit the master cube
	{
		Hit = true;
	}
	else//hit another small cube
	{
		direction.x = -direction.x;
		direction.y = direction.y;
	}
}

bool Box:: operator!=(Box b)
{
	if (Position != b.Position)
		return  true;
	else
		return false;
}

float Box::getXBuffer()
{
	return  2 * scaleVector.x;
}

float Box::getYBuffer()
{
	return  2 * scaleVector.y;
}

float Box::getZBuffer()
{
	return  2 * scaleVector.z;
}

void Box::setMVPMatrix(mat4 viewMatrix, mat4 projectionMatrix)
{
	MVP = projectionMatrix * viewMatrix * getModelMatrix();
}

void Box::setScaleMatrix(vec3 scale)
{
	scaleVector = scale;
	ScaleMatrix = glm::scale(mat4(1.0f), scaleVector);
}

void Box::setTranslationMatrix(vec3 pos)
{
	Position = pos;
	TranslationMatrix = glm::translate(glm::mat4(1.0f), Position);
}

void Box::setRotationMatrix(float angle, float x, float y, float z)
{
	RotationMatrix = glm::rotate(mat4(1.0f), angle, vec3(x, y, z));
}

void Box::setOrbitMatrix(vec3 pos, float angle, float x, float y, float z)
{
	OrbitMatrix = glm::rotate(glm::translate(glm::mat4(1.0f), pos), angle, vec3(x, y, z));
}

void Box::ChangeTexture()
{
	int img_width, img_height, channels;
	unsigned char *img = SOIL_load_image("data/images/metal.bmp", &img_width, &img_height, &channels, 0);
	glBindTexture(GL_TEXTURE_2D, vertexBufferData.Texture);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, img_width, img_height, 0, GL_RGB, GL_UNSIGNED_BYTE, img);
}

and Box.h

#pragma once
#include "GameObject.h"
#include "md2model.h"

class Box : public GameObject
{

private:
	mat4 MVP;
	mat4 ModelMatrix;
	mat4 RotationMatrix;
	mat4 OrbitMatrix;
	mat4 TranslationMatrix;
	mat4 ScaleMatrix;

public:
	void Draw(float deltaTime);
	void OnCollide(Box * box);
	virtual ObjectType getType() const { return BOX; }

	mat4 getModelMatrix() { return getOrbitMatrix()*getTranslationMatrix()* getRotationMatrix()*getScaleMatrix(); }

	mat4 getTranslationMatrix() { return translate(glm::mat4(1.0f), Position); }
	mat4 getRotationMatrix() { return RotationMatrix; }
	mat4 getScaleMatrix() { return ScaleMatrix; }
	mat4 getOrbitMatrix() { return OrbitMatrix; }
	vec3 getPosition(){ return Position; }


	void setOrbitMatrix(vec3 pos, float angle, float x, float y, float z);
	void setRotationMatrix(float angle, float x, float y, float z);
	void setScaleMatrix(vec3 scale);
	void setTranslationMatrix(vec3 pos);
	void setMVPMatrix(mat4 viewMatrix, mat4 projectionMatrix);

	bool Visible;
	void ChangeTexture();
	bool operator!=(Box b);
	float getXBuffer();
	float getYBuffer();
	float getZBuffer();

	void setPosition(vec3 position);

	Box(vec3 initialPosition, const char* imagePath, const string vertexShader, const string fragmentShader, char* modelPath, bool m, float sp, vec3 s, bool vis);

	vec3 Position;
	vec3 direction;
	vec3 scaleVector;
	float rotationAngle;
	bool Hit;
	bool master;
	float speed;
	float radius;
	
};

I'm not sure if either of these files populates the vector, however. I guess I just thought that vectors were populated because the boxes do get drawn to the screen, but just without the collision that I need.

[2kaud]

I'm not sure if either of these files populates the vector, however. I guess I just thought that vectors were populated because the boxes do get drawn to the screen

That is the code for the class Box. It can't populate the boxes vector as the boxes vector is defined within your code and isn't passed as a parameter to any function.

it look like the vector gameObjects is being populated with addresses of Box objects. Try changing

for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)

to

for (auto i = gameObjects.begin(); i != gameObjects.end(); ++i)

[Aideux]

That is the code for the class Box. It can't populate the boxes vector as the boxes vector is defined within your code and isn't passed as a parameter to any function.

it look like the vector gameObjects is being populated with addresses of Box objects. Try changing

for (vector<Box*>::iterator i = boxes.begin(); i != boxes.end(); ++i)

to

for (auto i = gameObjects.begin(); i != gameObjects.end(); ++i)

So I actually gave this a shot in the past, but the line

if (camera->getPosition().x >= ((*i)->Position.x - (*i)->getXBuffer()) && camera->getPosition().x <= ((*i)->Position.x + (*i)->getXBuffer()))

and

if (camera->getPosition().z >= ((*i)->Position.z - (*i)->getZBuffer()) && camera->getPosition().z <= ((*i)->Position.z + (*i)->getZBuffer()))

gets a whole bunch of errors because the X, Y, and Z locations of the boxes that I need collision for are set in the Box.cpp and Box.h classes, not the GameObject.cpp and GameObject.h classes. Is there any way I can work around this? It sounds like it might be a little counter-productive to rewrite both classes to get the positions from the other class, but I could be wrong. Again, I really appreciate all the help, you're really helping me make more sense of this.

[2kaud]

Class Box is derived from class GameObject. So consider

	for (auto i = gameObjects.begin(); i != gameObjects.end(); ++i)
	{
		if ((*i)->getType() == ObjectType::BOX)
		{
			auto b = (Box*)*i;
			if (camera->getPosition().x >= (b->Position.x - b->getXBuffer()) && camera->getPosition().x <= (b->Position.x + b->getXBuffer()))
			{
				if (camera->getPosition().z >= (b->Position.z - b->getZBuffer()) && camera->getPosition().z <= (b->Position.z + b->getZBuffer()))		//change to Z axis and get camera position instead of radius
				{
					o++;
					cout << o << endl;
					collided = true;
				}
			}
		}
	}

as the function getType() is virtual.

[Aideux]

Class Box is derived from class GameObject. So consider

	for (auto i = gameObjects.begin(); i != gameObjects.end(); ++i)
	{
		if ((*i)->getType() == ObjectType::BOX)
		{
			auto b = (Box*)*i;
			if (camera->getPosition().x >= (b->Position.x - b->getXBuffer()) && camera->getPosition().x <= (b->Position.x + b->getXBuffer()))
			{
				if (camera->getPosition().z >= (b->Position.z - b->getZBuffer()) && camera->getPosition().z <= (b->Position.z + b->getZBuffer()))		//change to Z axis and get camera position instead of radius
				{
					o++;
					cout << o << endl;
					collided = true;
				}
			}
		}
	}

as the function getType() is virtual.

That works! It enters the loop now, which is amazing! Unfortunately, it restricts camera movement upon loading, but I feel like I know why.

So the reason what you suggested I do works is because you cast the gameObject i as a box? Do you think you could explain that to me just so I know why what I was doing was wrong? Thank you so much, you have now idea how much I appreciate this!!

[2kaud]

When run, does the code reach the 2nd if statement - ie is the getType() returing ObjectType::BOX?

Box is derived from GameObject and gameObjects is a vector of pointers to GameObject. As Box is dereived from GameObject, gameObjects can store pointers to Box. So when iterating the gameObjects vector if the item is a BOX pointer then the pointer can be cast to a BOX pointer which is what b type is - a pointer to BOX. getType() is virtual so the class is polymorphic for this function.

See http://www.learncpp.com/cpp-tutorial...rived-objects/