//
// Book:      OpenGL(R) ES 2.0 Programming Guide
// Authors:   Aaftab Munshi, Dan Ginsburg, Dave Shreiner
// ISBN-10:   0321502795
// ISBN-13:   9780321502797
// Publisher: Addison-Wesley Professional
// URLs:      http://safari.informit.com/9780321563835
//            http://www.opengles-book.com
//

// ESUtil.c
//
//    A utility library for OpenGL ES.  This library provides a
//    basic common framework for the example applications in the
//    OpenGL ES 2.0 Programming Guide.
//

///
//  Includes
//
#include "esUtil.h"
#include <math.h>
#include <string.h>

#define PI 3.1415926535897932384626433832795f

void ESUTIL_API
esScale(ESMatrix *result, GLfloat sx, GLfloat sy, GLfloat sz) {
	result->m[0][0] *= sx;
	result->m[0][1] *= sx;
	result->m[0][2] *= sx;
	result->m[0][3] *= sx;
	result->m[1][0] *= sy;
	result->m[1][1] *= sy;
	result->m[1][2] *= sy;
	result->m[1][3] *= sy;
	result->m[2][0] *= sz;
	result->m[2][1] *= sz;
	result->m[2][2] *= sz;
	result->m[2][3] *= sz;
}

void ESUTIL_API
esTranslate(ESMatrix *result, GLfloat tx, GLfloat ty, GLfloat tz) {
	result->m[3][0] += (result->m[0][0] * tx + result->m[1][0] * ty + result->m[2][0] * tz);
	result->m[3][1] += (result->m[0][1] * tx + result->m[1][1] * ty + result->m[2][1] * tz);
	result->m[3][2] += (result->m[0][2] * tx + result->m[1][2] * ty + result->m[2][2] * tz);
	result->m[3][3] += (result->m[0][3] * tx + result->m[1][3] * ty + result->m[2][3] * tz);
}

void ESUTIL_API
esRotate(ESMatrix *result, GLfloat angle, GLfloat x, GLfloat y, GLfloat z) {
	GLfloat sinAngle, cosAngle;
	GLfloat mag = sqrtf(x * x + y * y + z * z);
	sinAngle = sinf(angle * PI / 180.0f);
	cosAngle = cosf(angle * PI / 180.0f);
	if (mag > 0.0f) {
		GLfloat xx, yy, zz, xy, yz, zx, xs, ys, zs;
		GLfloat oneMinusCos;
		ESMatrix rotMat;
		x /= mag;
		y /= mag;
		z /= mag;
		xx = x * x;
		yy = y * y;
		zz = z * z;
		xy = x * y;
		yz = y * z;
		zx = z * x;
		xs = x * sinAngle;
		ys = y * sinAngle;
		zs = z * sinAngle;
		oneMinusCos = 1.0f - cosAngle;
		rotMat.m[0][0] = (oneMinusCos * xx) + cosAngle;
		rotMat.m[0][1] = (oneMinusCos * xy) - zs;
		rotMat.m[0][2] = (oneMinusCos * zx) + ys;
		rotMat.m[0][3] = 0.0F;
		rotMat.m[1][0] = (oneMinusCos * xy) + zs;
		rotMat.m[1][1] = (oneMinusCos * yy) + cosAngle;
		rotMat.m[1][2] = (oneMinusCos * yz) - xs;
		rotMat.m[1][3] = 0.0F;
		rotMat.m[2][0] = (oneMinusCos * zx) - ys;
		rotMat.m[2][1] = (oneMinusCos * yz) + xs;
		rotMat.m[2][2] = (oneMinusCos * zz) + cosAngle;
		rotMat.m[2][3] = 0.0F;
		rotMat.m[3][0] = 0.0F;
		rotMat.m[3][1] = 0.0F;
		rotMat.m[3][2] = 0.0F;
		rotMat.m[3][3] = 1.0F;
		esMatrixMultiply(result, &rotMat, result);
	}
}

void ESUTIL_API
esFrustum(ESMatrix *result, float left, float right, float bottom, float top, float nearZ, float farZ) {
	float       deltaX = right - left;
	float       deltaY = top - bottom;
	float       deltaZ = farZ - nearZ;
	ESMatrix    frust;
	if ((nearZ <= 0.0f) || (farZ <= 0.0f) ||
			(deltaX <= 0.0f) || (deltaY <= 0.0f) || (deltaZ <= 0.0f)) {
		return;
	}
	frust.m[0][0] = 2.0f * nearZ / deltaX;
	frust.m[0][1] = frust.m[0][2] = frust.m[0][3] = 0.0f;
	frust.m[1][1] = 2.0f * nearZ / deltaY;
	frust.m[1][0] = frust.m[1][2] = frust.m[1][3] = 0.0f;
	frust.m[2][0] = (right + left) / deltaX;
	frust.m[2][1] = (top + bottom) / deltaY;
	frust.m[2][2] = -(nearZ + farZ) / deltaZ;
	frust.m[2][3] = -1.0f;
	frust.m[3][2] = -2.0f * nearZ * farZ / deltaZ;
	frust.m[3][0] = frust.m[3][1] = frust.m[3][3] = 0.0f;
	esMatrixMultiply(result, &frust, result);
}


void ESUTIL_API
esPerspective(ESMatrix *result, float fovy, float aspect, float nearZ, float farZ) {
	GLfloat frustumW, frustumH;
	frustumH = tanf(fovy / 360.0f * PI) * nearZ;
	frustumW = frustumH * aspect;
	esFrustum(result, -frustumW, frustumW, -frustumH, frustumH, nearZ, farZ);
}

void ESUTIL_API
esOrtho(ESMatrix *result, float left, float right, float bottom, float top, float nearZ, float farZ) {
	float       deltaX = right - left;
	float       deltaY = top - bottom;
	float       deltaZ = farZ - nearZ;
	ESMatrix    ortho;
	if ((deltaX == 0.0f) || (deltaY == 0.0f) || (deltaZ == 0.0f)) {
		return;
	}
	esMatrixLoadIdentity(&ortho);
	ortho.m[0][0] = 2.0f / deltaX;
	ortho.m[3][0] = -(right + left) / deltaX;
	ortho.m[1][1] = 2.0f / deltaY;
	ortho.m[3][1] = -(top + bottom) / deltaY;
	ortho.m[2][2] = -2.0f / deltaZ;
	ortho.m[3][2] = -(nearZ + farZ) / deltaZ;
	esMatrixMultiply(result, &ortho, result);
}


void ESUTIL_API
esMatrixMultiply(ESMatrix *result, ESMatrix *srcA, ESMatrix *srcB) {
	ESMatrix    tmp;
	int         i;
	for (i = 0; i < 4; i++) {
		tmp.m[i][0] =	(srcA->m[i][0] * srcB->m[0][0]) +
						(srcA->m[i][1] * srcB->m[1][0]) +
						(srcA->m[i][2] * srcB->m[2][0]) +
						(srcA->m[i][3] * srcB->m[3][0]) ;
		tmp.m[i][1] =	(srcA->m[i][0] * srcB->m[0][1]) +
						(srcA->m[i][1] * srcB->m[1][1]) +
						(srcA->m[i][2] * srcB->m[2][1]) +
						(srcA->m[i][3] * srcB->m[3][1]) ;
		tmp.m[i][2] =	(srcA->m[i][0] * srcB->m[0][2]) +
						(srcA->m[i][1] * srcB->m[1][2]) +
						(srcA->m[i][2] * srcB->m[2][2]) +
						(srcA->m[i][3] * srcB->m[3][2]) ;
		tmp.m[i][3] =	(srcA->m[i][0] * srcB->m[0][3]) +
						(srcA->m[i][1] * srcB->m[1][3]) +
						(srcA->m[i][2] * srcB->m[2][3]) +
						(srcA->m[i][3] * srcB->m[3][3]) ;
	}
	memcpy(result, &tmp, sizeof(ESMatrix));
}


void ESUTIL_API
esMatrixLoadIdentity(ESMatrix *result) {
	memset(result, 0x0, sizeof(ESMatrix));
	result->m[0][0] = 1.0f;
	result->m[1][1] = 1.0f;
	result->m[2][2] = 1.0f;
	result->m[3][3] = 1.0f;
}

