/*!
	\file
	\ingroup
	\author
	\brief
	\date    2001
*/


#include "TinyGL/gl_zgl.h"
#include "TinyGL/gl_msghandling.h"
#include <assert.h>
#include <math.h>
#include <string.h>


#define X v[0]
#define Y v[1]
#define Z v[2]
#define W v[3]


void glopMaterial( GLContext *c, GLParam *p ){
	int         mode = p[1].i;
	int         type = p[2].i;
	float      *v    = &p[3].f;
	int         i;
	GLMaterial *m;

	if( mode == GL_FRONT_AND_BACK ){
		p[1].i = GL_FRONT;
		glopMaterial( c, p );
		mode = GL_BACK;
	}
	if( mode == GL_FRONT ){
		m = &c->materials[0];
	}else{
		m = &c->materials[1];
	}

	switch( type ){
	case GL_EMISSION:
		for( i=0; i<4; i++ ){
			m->emission.v[i] = v[i];
		}
		break;
	case GL_AMBIENT:
		for( i=0; i<4; i++ ){
			m->ambient.v[i] = v[i];
		}
		break;
	case GL_DIFFUSE:
		for( i=0; i<4; i++ ){
			m->diffuse.v[i] = v[i];
		}
		break;
  case GL_SPECULAR:
    for(i=0;i<4;i++)
      m->specular.v[i]=v[i];
    break;
  case GL_SHININESS:
    m->shininess=v[0];
    m->shininess_i = (int)(v[0]/128)*SPECULAR_BUFFER_RESOLUTION;
    break;
  case GL_AMBIENT_AND_DIFFUSE:
    for(i=0;i<4;i++)
      m->diffuse.v[i]=v[i];
    for(i=0;i<4;i++)
      m->ambient.v[i]=v[i];
    break;
  default:
    assert(0);
	break;
  }
}

void glopColorMaterial( GLContext *c, GLParam *p ){
	int mode = p[1].i;
	int type = p[2].i;

	c->current_color_material_mode = mode;
	c->current_color_material_type = type;
}

void glopLight( GLContext *c, GLParam *p ){
	int      light = p[1].i;
	int      type  = p[2].i;
	V4       v;
	GLLight *l;
	int      i;
  
	assert( light >= GL_LIGHT0 && light < GL_LIGHT0+MAX_LIGHTS );

	l = &c->lights[light-GL_LIGHT0];

	for( i=0; i<4; i++ ){
		v.v[i] = p[3+i].f;
	}

  switch(type) {
  case GL_AMBIENT:
    l->ambient=v;
    break;
  case GL_DIFFUSE:
    l->diffuse=v;
    break;
  case GL_SPECULAR:
    l->specular=v;
    break;
  case GL_POSITION:
    {
      V4 pos;
      gl_M4_MulV4(&pos,c->matrix_stack_ptr[0],&v);

      l->position=pos;

      if (l->position.v[3] == 0) {
        l->norm_position.X=pos.X;
        l->norm_position.Y=pos.Y;
        l->norm_position.Z=pos.Z;
        
        gl_V3_Norm(&l->norm_position);
      }
    }
    break;
  case GL_SPOT_DIRECTION:
    for(i=0;i<3;i++) {
      l->spot_direction.v[i]=v.v[i];
      l->norm_spot_direction.v[i]=v.v[i];
    }
    gl_V3_Norm(&l->norm_spot_direction);
    break;
  case GL_SPOT_EXPONENT:
    l->spot_exponent=v.v[0];
    break;
  case GL_SPOT_CUTOFF:
    {
      float a=v.v[0];
      assert(a == 180 || (a>=0 && a<=90));
      l->spot_cutoff=a;
      if (a != 180) l->cos_spot_cutoff=(float)cos(a * M_PI / 180.0);
    }
    break;
  case GL_CONSTANT_ATTENUATION:
    l->attenuation[0]=v.v[0];
    break;
  case GL_LINEAR_ATTENUATION:
    l->attenuation[1]=v.v[0];
    break;
  case GL_QUADRATIC_ATTENUATION:
    l->attenuation[2]=v.v[0];
    break;
  default:
    assert(0);
  }
}
  

void glopLightModel( GLContext *c, GLParam *p ){
  int    pname = p[1].i;
  float *v     = &p[2].f;
  int    i;

  switch(pname) {
  case GL_LIGHT_MODEL_AMBIENT:
    for(i=0;i<4;i++) 
      c->ambient_light_model.v[i]=v[i];
    break;
  case GL_LIGHT_MODEL_LOCAL_VIEWER:
    c->local_light_model=(int)v[0];
    break;
  case GL_LIGHT_MODEL_TWO_SIDE:
    c->light_model_two_side = (int)v[0];
    break;
  default:
    tgl_warning("glopLightModel: illegal pname: 0x%x\n", pname);
    /*assert(0);*/
    break;
  }
}


static /*inline*/ float clampf( float a, float min, float max ){
	if( a < min ){
		return min;
	}else if( a > max ){
		return max;
	}else{
		return a;
	}
}

void gl_enable_disable_light( GLContext *c, int light, int v ){
	GLLight *l = &c->lights[light];

	if( v && !l->enabled ){
		l->enabled     = 1;
		l->next        = c->first_light;
		c->first_light = l;
		l->prev        = NULL;
	}else if( !v && l->enabled ){
		l->enabled = 0;
		if( l->prev == NULL){
			c->first_light = l->next;
		}else{
			l->prev->next = l->next;
		}
		if( l->next != NULL ){
			l->next->prev = l->prev;
		}
  }
}

/* non optimized lightening model */
void gl_shade_vertex( GLContext *c, GLVertex *v ){
  float R,G,B,A;
  GLMaterial *m;
  GLLight *l;
  V3 n,s,d;
  float dist,tmp,att,dot,dot_spot,dot_spec;
  int twoside = c->light_model_two_side;

  m=&c->materials[0];

  n.X=v->normal.X;
  n.Y=v->normal.Y;
  n.Z=v->normal.Z;

  R=m->emission.v[0]+m->ambient.v[0]*c->ambient_light_model.v[0];
  G=m->emission.v[1]+m->ambient.v[1]*c->ambient_light_model.v[1];
  B=m->emission.v[2]+m->ambient.v[2]*c->ambient_light_model.v[2];
  A=clampf(m->diffuse.v[3],0,1);

  for(l=c->first_light;l!=NULL;l=l->next) {
    float lR,lB,lG;
    
    /* ambient */
    lR=l->ambient.v[0] * m->ambient.v[0];
    lG=l->ambient.v[1] * m->ambient.v[1];
    lB=l->ambient.v[2] * m->ambient.v[2];

    if (l->position.v[3] == 0) {
      /* light at infinity */
      d.X=l->position.v[0];
      d.Y=l->position.v[1];
      d.Z=l->position.v[2];
      att=1;
    } else {
      /* distance attenuation */
      d.X=l->position.v[0]-v->ec.v[0];
      d.Y=l->position.v[1]-v->ec.v[1];
      d.Z=l->position.v[2]-v->ec.v[2];
      dist=(float)sqrt(d.X*d.X+d.Y*d.Y+d.Z*d.Z);
      if (dist>1E-3) {
        tmp=1/dist;
        d.X*=tmp;
        d.Y*=tmp;
        d.Z*=tmp;
      }
      att=1/(l->attenuation[0]+dist*(l->attenuation[1]+
				     dist*l->attenuation[2]));
    }
    dot=d.X*n.X+d.Y*n.Y+d.Z*n.Z;
    if (twoside && dot < 0) dot = -dot;
    if (dot>0) {
      /* diffuse light */
      lR+=dot * l->diffuse.v[0] * m->diffuse.v[0];
      lG+=dot * l->diffuse.v[1] * m->diffuse.v[1];
      lB+=dot * l->diffuse.v[2] * m->diffuse.v[2];

      /* spot light */
      if (l->spot_cutoff != 180) {
        dot_spot=-(d.X*l->norm_spot_direction.v[0]+
                   d.Y*l->norm_spot_direction.v[1]+
                   d.Z*l->norm_spot_direction.v[2]);
        if (twoside && dot_spot < 0) dot_spot = -dot_spot;
        if (dot_spot < l->cos_spot_cutoff) {
          /* no contribution */
          continue;
        } else {
          /* TODO: optimize */
          if (l->spot_exponent > 0) {
            att=(float)(  att*pow(dot_spot,l->spot_exponent)  );
          }
        }
      }

      /* specular light */
      
      if (c->local_light_model) {
        V3 vcoord;
        vcoord.X=v->ec.X;
        vcoord.Y=v->ec.Y;
        vcoord.Z=v->ec.Z;
        gl_V3_Norm(&vcoord);
        s.X=d.X-vcoord.X;
        s.Y=d.Y-vcoord.X;
        s.Z=d.Z-vcoord.X;
      } else {
        s.X=d.X;
        s.Y=d.Y;
        s.Z=d.Z+1;
      }
      dot_spec=n.X*s.X+n.Y*s.Y+n.Z*s.Z;
      if (twoside && dot_spec < 0) dot_spec = -dot_spec;
      if (dot_spec>0) {
        GLSpecBuf *specbuf;
        int idx;
        tmp=(float)sqrt(s.X*s.X+s.Y*s.Y+s.Z*s.Z);
        if (tmp > 1E-3) {
          dot_spec=dot_spec / tmp;
        }
      
        /* TODO: optimize */
        /* testing specular buffer code */
        /* dot_spec= pow(dot_spec,m->shininess);*/
        specbuf = specbuf_get_buffer(c, m->shininess_i, m->shininess);
        idx = (int)(dot_spec*SPECULAR_BUFFER_SIZE);
        if (idx > SPECULAR_BUFFER_SIZE) idx = SPECULAR_BUFFER_SIZE;
        dot_spec = specbuf->buf[idx];
        lR+=dot_spec * l->specular.v[0] * m->specular.v[0];
        lG+=dot_spec * l->specular.v[1] * m->specular.v[1];
        lB+=dot_spec * l->specular.v[2] * m->specular.v[2];
      }
    }

    R+=att * lR;
    G+=att * lG;
    B+=att * lB;
  }

  v->color.v[0]=clampf(R,0,1);
  v->color.v[1]=clampf(G,0,1);
  v->color.v[2]=clampf(B,0,1);
  v->color.v[3]=A;
}