/*
 *  Copyright (C) 2018-2020 - Vito Caputo - <vcaputo@pengaru.com>
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 3 as published
 *  by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <SDL.h>

#include <stage.h>

#include "glad.h"
#include "m4f.h"
#include "sad-node.h"
#include "shader-node.h"
#include "v3f.h"


static const char	*sad_vs = ""
	"#version 120\n"

	"uniform mat4 model_x;"

	"attribute vec3 i_vertex;"
	"attribute vec2 i_texcoord;"

	"void main()"
	"{"
	"	gl_TexCoord[0].xy = i_texcoord;"
	"	gl_Position = model_x * vec4(i_vertex, 1.f);"
	"}"
"";


static const char	*sad_fs = ""
	"#version 120\n"

	"uniform float alpha;"
	"uniform float time;"
	"uniform float T;"
	"uniform vec3 color;"
	"uniform float seed; "
	"uniform float rand;"

	"const vec2	leye = vec2(-.5f, .5f);"
	"const vec2	reye = vec2(.5f, .5f);"
	"const vec2	frown = vec2(0.f, -1.2f);"
	"const float	eye_radius = .2f;"
	"const float	frown_radius = 1.f;"
	"const float	lip_thickness = .1f;"

	"void eye(in vec2 center, inout vec4 c)"
	"{"
	"	float	r = length(center - gl_TexCoord[0].st);"

	"	if (r <= eye_radius) {"
	"		float	v = (1.f / eye_radius) * r;"

	"		v = 1.f - pow(v, 20);"
	"		c = vec4(color * v, v);"
	"	}"
	"}"

	"void arc(vec2 center, inout vec4 c)"
	"{"
	"	float	r = length(center - gl_TexCoord[0].st);"

	"	if (r >= frown_radius - lip_thickness &&"
	"	    r <= frown_radius + lip_thickness) {"
	"		float	v = cos((r - (frown_radius + lip_thickness)) * 1.f / (lip_thickness * 2.f) * 6.28) * .5f + .5f;"

	"		v = 1.f - pow(v, 20);"
	"		c = vec4(color * v, v);"
	"	}"
	"}"

	"void main()"
	"{"
	"	float	r = length(gl_TexCoord[0].st);"
	"	vec4	c = vec4(0.f, 0.f, 0.f, 0.f);"

	"	eye(leye, c);"
	"	eye(reye, c);"
	"	arc(frown, c);"

	"	gl_FragColor = c;"
	"}"
"";


static void sad_uniforms(shader_t *shader, void *uniforms_ctxt, void *render_ctxt, unsigned n_uniforms, const int *uniforms, const m4f_t *model_x, float alpha)
{
	v3f_t	*color = uniforms_ctxt;

	glUniform1f(uniforms[0], alpha);
	glUniformMatrix4fv(uniforms[1], 1, GL_FALSE, &model_x->m[0][0]);
	glUniform3f(uniforms[2], color->x, color->y, color->z);
}


/* create sad face rendering stage */
stage_t * sad_node_new(const stage_conf_t *conf, const m4f_t *model_x, const v3f_t *color)
{
	assert(model_x);
	assert(color);

	return	shader_node_new_src(conf, sad_vs, sad_fs, model_x, sad_uniforms, (void *)color, 3,
			(const char *[]){
				"alpha",
				"model_x",
				"color",
			}
		);
}