/*
  Simple Demo for GLSL
  www.lighthouse3d.com
  
  tweaked a bit by andy
*/

#include "GL/glew.h"

#ifdef __linux__
#include <GL/glut.h>
#endif

#ifdef __APPLE__
#include <glut.h>
#endif

#ifdef _WIN32
#include "glut.h"
#endif

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>


////////////////////////////////////////////////////////////////////////////////

char *textFileRead(char *fn)
{
	FILE *fp;
	char *content = NULL;

	int count=0;

	if (fn != NULL) {
		fp = fopen(fn,"rt");

		if (fp != NULL) {
      
      fseek(fp, 0, SEEK_END);
      count = ftell(fp);
      rewind(fp);

			if (count > 0) {
				content = (char *)malloc(sizeof(char) * (count+1));
				count = fread(content,sizeof(char),count,fp);
				content[count] = '\0';
			}
			fclose(fp);
		}
	}
	
	if (content == NULL)
	   {
	   fprintf(stderr, "ERROR: could not load in file %s\n", fn);
	   exit(1);
	   }
	return content;
}           

////////////////////////////////////////////////////////////////////////////////

GLuint ptbrick, pttoon;

float lpos[4] = {1.0, 0.5, 1.0, 0.0};

void changeSize(int w, int h) {

	// Prevent a divide by zero, when window is too short
	// (you cant make a window of zero width).
	if(h == 0)
		h = 1;

	float ratio = 1.0* w / h;

	// Reset the coordinate system before modifying
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	
	// Set the viewport to be the entire window
    glViewport(0, 0, w, h);

	// Set the correct perspective.
	gluPerspective(45, ratio, 1, 1000);
	glMatrixMode(GL_MODELVIEW);
}

////////////////////////////////////////////////////////////////////////////////

void printShaderLog(GLuint obj)
{
    GLint infoLogLength = 0;
    GLsizei charsWritten  = 0;
    GLchar *infoLog;

    glGetShaderiv(obj, GL_INFO_LOG_LENGTH, &infoLogLength);

    if (infoLogLength > 0)
    {
        infoLog = (char *) malloc(infoLogLength);
        glGetShaderInfoLog(obj, infoLogLength, &charsWritten, infoLog);
		printf("%s\n",infoLog);
        free(infoLog);
    }
}

void printProgramLog(GLuint obj)
{
    GLint infoLogLength = 0;
    GLsizei charsWritten  = 0;
    GLchar *infoLog;

    glGetProgramiv(obj, GL_INFO_LOG_LENGTH, &infoLogLength);

    if (infoLogLength > 0)
    {
        infoLog = (char *) malloc(infoLogLength);
        glGetProgramInfoLog(obj, infoLogLength, &charsWritten, infoLog);
		printf("%s\n",infoLog);
        free(infoLog);
    }
}

////////////////////////////////////////////////////////////////////////////////

void setBrickParams(GLuint p)
{
	GLint loc;
	
	float bColor[3] = {1.0, 0.3, 0.2};
	float mColor[3] = {0.85, 0.86, 0.84};
    float bSize[2]  = {0.30, 0.15};
    float bPct[2]   = {0.90, 0.85};
    float mPct[2];
    mPct[0] = 1.0 - bPct[0];
    mPct[1] = 1.0 - bPct[1];
	float lPos[3]   = {0.0, 0.0, 4.0}; //maybe make this more generic later on

	loc = glGetUniformLocation(p,"BrickColor");
    glUniform3fv(loc, 1, bColor);

	loc = glGetUniformLocation(p,"MortarColor");
    glUniform3fv(loc, 1, mColor);

	loc = glGetUniformLocation(p,"BrickSize");
    glUniform2fv(loc, 1, bSize);
    
    loc = glGetUniformLocation(p,"BrickPct");
    glUniform2fv(loc, 1, bPct);

    loc = glGetUniformLocation(p,"MortarPct");
    glUniform2fv(loc, 1, mPct);

	loc = glGetUniformLocation(p,"LightPosition");
    glUniform3fv(loc, 1, lPos);
}

////////////////////////////////////////////////////////////////////////////////

void setToonParams(GLuint p)
{
	GLint loc1,loc2,loc3,loc4;
	float specIntensity = 0.98;
	float sc[4] = {0.8,0.8,0.8,1.0};
	float threshold[2] = {0.5,0.25};
	float colors[12] = {0.4,0.4,0.8,1.0,
						0.2,0.2,0.4,1.0,
						0.1,0.1,0.1,1.0};
						
	loc1 = glGetUniformLocation(p,"specIntensity");
	glUniform1f(loc1,specIntensity);

	loc2 = glGetUniformLocation(p,"specColor");
    //glUniform4f(loc2,sc[0],sc[1],sc[2],sc[3]);
    glUniform4fv(loc2,1,sc);
    
	loc3 = glGetUniformLocation(p,"t");
	glUniform1fv(loc3,2,threshold);

	loc4 = glGetUniformLocation(p,"colors");
	glUniform4fv(loc4,3,colors);
}

////////////////////////////////////////////////////////////////////////////////

float rotAmount = 0;

void renderScene(void) {

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glLoadIdentity();
	gluLookAt(0.0,3.0,6.0, 
		      0.0,0.0,-1.0,
			  0.0f,1.0f,0.0f);

	glLightfv(GL_LIGHT0, GL_POSITION, lpos);
	glRotatef(rotAmount,0,1,0);

    // draw the brick platform

    glUseProgram(ptbrick);
	setBrickParams(ptbrick);

	glutSolidCube(2);
	
	// draw the toon-shaded teapot
	
	glTranslatef(0,1.5,0);

    glUseProgram(pttoon);
    setToonParams(pttoon);
    
    glutSolidTeapot(1);

    rotAmount+= 0.1;

	glutSwapBuffers();
}

////////////////////////////////////////////////////////////////////////////////

void processNormalKeys(unsigned char key, int x, int y) {

	if (key == 27) 
		exit(0);
}


////////////////////////////////////////////////////////////////////////////////

GLuint setShaders(char * vert, char * frag) {
    GLuint v,f, pro;
	char *vs,*fs;

	v = glCreateShader(GL_VERTEX_SHADER);
	f = glCreateShader(GL_FRAGMENT_SHADER);

	vs = textFileRead(vert);
	fs = textFileRead(frag);

	const char * vv = vs;
	const char * ff = fs;

	glShaderSource(v, 1, &vv,NULL);
	glShaderSource(f, 1, &ff,NULL);

	free(vs);free(fs);

	glCompileShader(v);
	glCompileShader(f);

	printShaderLog(v);
	printShaderLog(f);

	pro = glCreateProgram();
	glAttachShader(pro,v);
	glAttachShader(pro,f);

	glLinkProgram(pro);
	printProgramLog(pro);
	
	return(pro);
}

////////////////////////////////////////////////////////////////////////////////

int main(int argc, char **argv) {
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
	glutInitWindowPosition(100,100);
	glutInitWindowSize(320,320);
	glutCreateWindow("GLSL");

	glutDisplayFunc(renderScene);
	glutIdleFunc(renderScene);
	glutReshapeFunc(changeSize);
	glutKeyboardFunc(processNormalKeys);

	glEnable(GL_DEPTH_TEST);
	glClearColor(0.0,0.0,0.0,1.0);

	glewInit();
	if (GLEW_ARB_vertex_shader && GLEW_ARB_fragment_shader)
		printf("Ready for GLSL\n");
	else {
		printf("No GLSL support\n");
		exit(1);
	}

	ptbrick = setShaders("./brick.vert", "./brick.frag");
	pttoon = setShaders("./toon.vert", "./toon3.frag");
	
	glutMainLoop();
	return 0;
}