gltut / Tut 08 Getting Oriented / Interpolation.cpp

Jason McKesson 6feca88 



Jason McKesson da7c819 
Jason McKesson 74c4b9b 
Jason McKesson 6feca88 
































































Jason McKesson 0794d2b 



Jason McKesson 6feca88 





Jason McKesson 0794d2b 







Jason McKesson 6feca88 












Jason McKesson 2b423ba 

Jason McKesson 6feca88 























Jason McKesson 0794d2b 





























Jason McKesson 6feca88 




























































Jason McKesson 0794d2b 
Jason McKesson 6feca88 


Jason McKesson 0794d2b 
Jason McKesson 6feca88 
















































































































Jason McKesson f314aea 
#include <string>
#include <vector>
#include <stack>
#include <math.h>
#include <stdio.h>
#include <glload/gl_3_3.h>
#include <GL/freeglut.h>
#include "../framework/framework.h"
#include "../framework/Mesh.h"
#include "../framework/MatrixStack.h"
#include "../framework/Timer.h"
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glm/gtc/quaternion.hpp>

#define ARRAY_COUNT( array ) (sizeof( array ) / (sizeof( array[0] ) * (sizeof( array ) != sizeof(void*) || sizeof( array[0] ) <= sizeof(void*))))

GLuint theProgram;
GLuint positionAttrib;
GLuint colorAttrib;

GLuint modelToCameraMatrixUnif;
GLuint cameraToClipMatrixUnif;
GLuint baseColorUnif;

glm::mat4 cameraToClipMatrix(0.0f);

float CalcFrustumScale(float fFovDeg)
{
	const float degToRad = 3.14159f * 2.0f / 360.0f;
	float fFovRad = fFovDeg * degToRad;
	return 1.0f / tan(fFovRad / 2.0f);
}

const float fFrustumScale = CalcFrustumScale(20.0f);

void InitializeProgram()
{
	std::vector<GLuint> shaderList;

	shaderList.push_back(Framework::LoadShader(GL_VERTEX_SHADER, "PosColorLocalTransform.vert"));
	shaderList.push_back(Framework::LoadShader(GL_FRAGMENT_SHADER, "ColorMultUniform.frag"));

	theProgram = Framework::CreateProgram(shaderList);

	positionAttrib = glGetAttribLocation(theProgram, "position");
	colorAttrib = glGetAttribLocation(theProgram, "color");

	modelToCameraMatrixUnif = glGetUniformLocation(theProgram, "modelToCameraMatrix");
	cameraToClipMatrixUnif = glGetUniformLocation(theProgram, "cameraToClipMatrix");
	baseColorUnif = glGetUniformLocation(theProgram, "baseColor");

	float fzNear = 1.0f; float fzFar = 600.0f;

	cameraToClipMatrix[0].x = fFrustumScale;
	cameraToClipMatrix[1].y = fFrustumScale;
	cameraToClipMatrix[2].z = (fzFar + fzNear) / (fzNear - fzFar);
	cameraToClipMatrix[2].w = -1.0f;
	cameraToClipMatrix[3].z = (2 * fzFar * fzNear) / (fzNear - fzFar);

	glUseProgram(theProgram);
	glUniformMatrix4fv(cameraToClipMatrixUnif, 1, GL_FALSE, glm::value_ptr(cameraToClipMatrix));
	glUseProgram(0);
}

Framework::Mesh *g_pShip = NULL;

static glm::fquat g_Orients[] =
{
	glm::fquat(0.7071f, 0.7071f, 0.0f, 0.0f),
	glm::fquat(0.5f, 0.5f, -0.5f, 0.5f),
	glm::fquat(-0.4895f, -0.7892f, -0.3700f, -0.02514f),
	glm::fquat(0.4895f, 0.7892f, 0.3700f, 0.02514f),

	glm::fquat(0.3840f, -0.1591f, -0.7991f, -0.4344f),
	glm::fquat(0.5537f, 0.5208f, 0.6483f, 0.0410f),
	glm::fquat(0.0f, 0.0f, 1.0f, 0.0f),
};

static char g_OrientKeys[] =
{
	'q',
	'w',
	'e',
	'r',

	't',
	'y',
	'u',
};

//Called after the window and OpenGL are initialized. Called exactly once, before the main loop.
void init()
{
	InitializeProgram();

	try
	{
		g_pShip = new Framework::Mesh("Ship.xml");
	}
	catch(std::exception &except)
	{
		printf("%s\n", except.what());
		throw;
	}

	glEnable(GL_CULL_FACE);
	glCullFace(GL_BACK);
	glFrontFace(GL_CW);

	glEnable(GL_DEPTH_TEST);
	glDepthMask(GL_TRUE);
	glDepthFunc(GL_LEQUAL);
	glDepthRange(0.0f, 1.0f);
}

glm::vec4 Vectorize(const glm::fquat theQuat)
{
	glm::vec4 ret;

	ret.x = theQuat.x;
	ret.y = theQuat.y;
	ret.z = theQuat.z;
	ret.w = theQuat.w;

	return ret;
}

glm::fquat Lerp(const glm::fquat &v0, const glm::fquat &v1, float alpha)
{
	glm::vec4 start = Vectorize(v0);
	glm::vec4 end = Vectorize(v1);
	glm::vec4 interp = glm::mix(start, end, alpha);

	printf("alpha: %f, (%f, %f, %f, %f)\n", alpha, interp.w, interp.x, interp.y, interp.z);

	interp = glm::normalize(interp);
	return glm::fquat(interp.w, interp.x, interp.y, interp.z);
}

glm::fquat Slerp(const glm::fquat &v0, const glm::fquat &v1, float alpha)
{
	float dot = glm::dot(v0, v1);

	const float DOT_THRESHOLD = 0.9995f;
	if (dot > DOT_THRESHOLD)
		return Lerp(v0, v1, alpha);

	glm::clamp(dot, -1.0f, 1.0f);
	float theta_0 = acosf(dot);
	float theta = theta_0*alpha;

	glm::fquat v2 = v1 - v0*dot;
	v2 = glm::normalize(v2);

	return v0*cos(theta) + v2*sin(theta);
}

class Orientation
{
public:
	Orientation()
		: m_bIsAnimating(false)
		, m_ixCurrOrient(0)
		, m_bSlerp(false)
	{}

	bool ToggleSlerp()
	{
		m_bSlerp = !m_bSlerp;
		return m_bSlerp;
	}

	glm::fquat GetOrient() const
	{
		if(m_bIsAnimating)
			return m_anim.GetOrient(g_Orients[m_ixCurrOrient], m_bSlerp);
		else
			return g_Orients[m_ixCurrOrient];
	}

	bool IsAnimating() const {return m_bIsAnimating;}

	void UpdateTime()
	{
		if(m_bIsAnimating)
		{
			bool bIsFinished = m_anim.UpdateTime();
			if(bIsFinished)
			{
				m_bIsAnimating = false;
				m_ixCurrOrient = m_anim.GetFinalIx();
			}
		}
	}

	void AnimateToOrient(int ixDestination)
	{
		if(m_ixCurrOrient == ixDestination)
			return;

		m_anim.StartAnimation(ixDestination, 1.0f);
		m_bIsAnimating = true;
	}

private:
	class Animation
	{
	public:
		//Returns true if the animation is over.
		bool UpdateTime()
		{
			return m_currTimer.Update();
		}

		glm::fquat GetOrient(const glm::fquat &initial, bool bSlerp) const
		{
			if(bSlerp)
			{
				return Slerp(initial, g_Orients[m_ixFinalOrient], m_currTimer.GetAlpha());
			}
			else
			{
				return Lerp(initial, g_Orients[m_ixFinalOrient], m_currTimer.GetAlpha());
			}

			return initial;
		}

		void StartAnimation(int ixDestination, float fDuration)
		{
			m_ixFinalOrient = ixDestination;
			m_currTimer = Framework::Timer(Framework::Timer::TT_SINGLE, fDuration);
		}

		int GetFinalIx() const {return m_ixFinalOrient;}

	private:
		int m_ixFinalOrient;
		Framework::Timer m_currTimer;
	};

	bool m_bIsAnimating;
	int m_ixCurrOrient;
	bool m_bSlerp;

	Animation m_anim;
};

Orientation g_orient;

class Animation
{
public:

private:
	glm::fquat m_finalOrient;
};

//Called to update the display.
//You should call glutSwapBuffers after all of your rendering to display what you rendered.
//If you need continuous updates of the screen, call glutPostRedisplay() at the end of the function.
void display()
{
	g_orient.UpdateTime();

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glClearDepth(1.0f);
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	Framework::MatrixStack currMatrix;
	currMatrix.Translate(glm::vec3(0.0f, 0.0f, -200.0f));
	currMatrix.ApplyMatrix(glm::mat4_cast(g_orient.GetOrient()));

	glUseProgram(theProgram);
	currMatrix.Scale(3.0, 3.0, 3.0);
	currMatrix.RotateX(-90);
	//Set the base color for this object.
	glUniform4f(baseColorUnif, 1.0, 1.0, 1.0, 1.0);
	glUniformMatrix4fv(modelToCameraMatrixUnif, 1, GL_FALSE, glm::value_ptr(currMatrix.Top()));

	g_pShip->Render("tint");

	glUseProgram(0);

	glutSwapBuffers();
	glutPostRedisplay();
}

//Called whenever the window is resized. The new window size is given, in pixels.
//This is an opportunity to call glViewport or glScissor to keep up with the change in size.
void reshape (int w, int h)
{
	cameraToClipMatrix[0].x = fFrustumScale * (h / (float)w);
	cameraToClipMatrix[1].y = fFrustumScale;

	glUseProgram(theProgram);
	glUniformMatrix4fv(cameraToClipMatrixUnif, 1, GL_FALSE, glm::value_ptr(cameraToClipMatrix));
	glUseProgram(0);

	glViewport(0, 0, (GLsizei) w, (GLsizei) h);
}

void ApplyOrientation(int iIndex)
{
	if(!g_orient.IsAnimating())
		g_orient.AnimateToOrient(iIndex);
}


//Called whenever a key on the keyboard was pressed.
//The key is given by the ''key'' parameter, which is in ASCII.
//It's often a good idea to have the escape key (ASCII value 27) call glutLeaveMainLoop() to 
//exit the program.
void keyboard(unsigned char key, int x, int y)
{
	switch (key)
	{
	case 27:
		glutLeaveMainLoop();
		break;
	case 32:
		{
			bool bSlerp = g_orient.ToggleSlerp();
			printf(bSlerp ? "Slerp\n" : "Lerp\n");
		}
		break;
	}

	for(int iOrient = 0; iOrient < ARRAY_COUNT(g_OrientKeys); iOrient++)
	{
		if(key == g_OrientKeys[iOrient])
			ApplyOrientation(iOrient);
	}
}


unsigned int defaults(unsigned int displayMode, int &width, int &height) {return displayMode;}
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