#include <GL/gl.h>
#include <cmath>
#include <string>
#include <iostream>
#include "point_aux.h"

using namespace std;
namespace Graphics
{
	namespace {

		const string prg_str = "!!ARBvp1.0\n"
		"\n"
		"# Per-vertex inputs\n"
		"ATTRIB iPos         = vertex.position;\n"
		"ATTRIB iNormal      = vertex.normal;\n"
		"\n"
		"# Constant Parameters\n"
		"PARAM  mvinv[4]     = { state.matrix.modelview.invtrans };\n"
		"PARAM  mvp[4]       = { state.matrix.mvp };\n"
		"PARAM  pt_sz_sc     = program.env[0]; \n"
		"PARAM  lightDir     = state.light[0].position;\n"
		"PARAM  halfDir      = state.light[0].half;\n"
		"PARAM  specExp      = state.material.shininess;\n"
		"PARAM  ambientCol   = state.lightprod[0].ambient;\n"
		"PARAM  diffuseCol   = state.lightprod[0].diffuse;\n"
		"PARAM  specularCol  = state.lightprod[0].specular;\n"
		"\n"
		"# Per-vertex outputs\n"
		"OUTPUT oPos         = result.position;\n"
		"OUTPUT oPointSize   = result.pointsize;\n"
		"OUTPUT oColor       = result.color;\n"
		"\n"
		"# Temp variables\n"
		"TEMP inv_z, z;\n"
		"TEMP xfNormal, temp, dots;\n"
		"\n"
		"# Transform Vertex to clip coords\n"
		"DP4 oPos.x, mvp[0], iPos;\n"
		"DP4 oPos.y, mvp[1], iPos;\n"
		"DP4 oPos.z, mvp[2], iPos;\n"
		"DP4 oPos.w, mvp[3], iPos;\n"
		"\n"
		"# Transform the normal to eye coordinates.\n"
		"DP3   xfNormal.x, mvinv[0], iNormal;\n"
		"DP3   xfNormal.y, mvinv[1], iNormal;\n"
		"DP3   xfNormal.z, mvinv[2], iNormal;\n"
		"\n"
		"# Normalize normal\n" 
		"DP3 xfNormal.w, xfNormal, xfNormal;\n"
		"RSQ xfNormal.w, xfNormal.w;\n"
		"MUL xfNormal.xyz, xfNormal.w, xfNormal;"
		"\n"
		"# Compute diffuse and specular dot products and use LIT to compute\n"
		"# lighting coefficients.\n"
		"DP3   dots.x, xfNormal, lightDir;\n"
		"DP3   dots.y, xfNormal, halfDir;\n"
		"MOV   dots.w, specExp.x;\n"
		"LIT   dots, dots;\n"
		"\n"
		"# Accumulate color contributions.\n"
		"MAD   temp, dots.y, diffuseCol, ambientCol;\n"
		"MAD   oColor.xyz, dots.z, specularCol, temp;\n"
		"MOV   oColor.w, diffuseCol.w;\n"
		"\n"
		"#Compute point size\n"
		"DP4 z, mvp[2], iPos;\n"
		"RCP inv_z, z.x; \n"
		"MUL oPointSize, inv_z.x, pt_sz_sc.x;\n"
		"\n"
		"END\n";
	}



	void set_point_size()
	{
		int viewport[4];
		float mat[16];
		glGetFloatv(GL_PROJECTION_MATRIX, mat);
		glGetIntegerv(GL_VIEWPORT, viewport);

#ifdef USE_POINT_SCALING
 		const float H = viewport[2];
 		const float h = 2.0f/mat[0];
 		const float D0 = sqrt(2.0f)*H/h;
 		const float k = 1.0f/(1.0f + 2*CMN::sqr(1/mat[0]));
 		const float atten[3] = {0,0,CMN::sqr(1/D0)*k};
		glPointParameterfvEXT(GL_DISTANCE_ATTENUATION_EXT,atten);
 		glPointSize(1.0f);
#endif

		glEnable(GL_POINT_SMOOTH);
		glEnable(GL_VERTEX_PROGRAM_ARB);
		unsigned int vtxpgmID=0;
		glGenProgramsARB(1, &vtxpgmID);
		glBindProgramARB(GL_VERTEX_PROGRAM_ARB, vtxpgmID);
		glEnable(GL_VERTEX_PROGRAM_POINT_SIZE_ARB);
		glProgramStringARB( GL_VERTEX_PROGRAM_ARB, GL_PROGRAM_FORMAT_ASCII_ARB,
												prg_str.length(), prg_str.data());
		const float D = mat[0]*viewport[2]/sqrt(2.0f);
		glProgramEnvParameter4fARB( GL_VERTEX_PROGRAM_ARB, 0, D, 0.0f, 0.0f, 0.0f );
 		cout <<  D << " " << glGetString(GL_PROGRAM_ERROR_STRING_ARB) << endl;
	}
}