1 files changed, 93 insertions, 0 deletions
diff --git a/src/plasma-node.c b/src/plasma-node.c
new file mode 100644
index 0000000..1bc0e40
--- /dev/null
+++ b/src/plasma-node.c
@@ -0,0 +1,93 @@
+/*
+ *  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 <play.h>
+#include <stage.h>
+
+#include "glad.h"
+#include "plasma-node.h"
+#include "shader-node.h"
+
+
+static const char	*plasma_vs = ""
+	"#version 120\n"
+
+	"attribute vec3 vertex;"
+	"attribute vec2 texcoord;"
+
+	"void main()"
+	"{"
+	"	gl_TexCoord[0].xy = texcoord;"
+	//"	gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;"
+	"	gl_Position = vec4(vertex, 1.f);"
+	"}"
+"";
+
+
+// derived from https://www.bidouille.org/prog/plasma
+static const char	*plasma_fs = ""
+	"#version 120\n"
+
+	"#define PI 3.1415926535897932384626433832795\n"
+
+	"uniform float alpha;"
+	"uniform float time;"
+
+	"void main() {"
+	"	float v;"
+	"	float stime = sin(time * .01f) * 100.f;"
+
+	"	vec2 c = gl_TexCoord[0].st;"
+
+	// this zooms the texture coords in and out a bit with time
+	"	c *= (sin(stime * .01f) *.5f + .5f) * 3.f + 1.f;"
+
+	// plasma calculations, stime instead of time directly to vary directions and speed
+	"	v = sin((c.x + stime));"
+	"	v += sin((c.y + stime) * .5f);"
+	"	v += sin((c.x + c.y +stime) * .5f);"
+
+	"	c += vec2(sin(stime * .33f), cos(stime * .5f)) * 3.f;"
+
+	"	v += sin(sqrt(c.x * c.x + c.y * c.y + 1.f) + stime);"
+
+	"	vec3 col = vec3(cos(PI * v + sin(time)), sin(PI * v + cos(time * .33f)), cos(PI * v + sin(time * .66f)));"
+	"	gl_FragColor = vec4(col * .5f + .5f, alpha);"
+	"}"
+"";
+
+
+static void plasma_uniforms(void *uniforms_ctxt, void *render_ctxt, unsigned n_uniforms, const int *uniforms, const m4f_t *model_x, float alpha)
+{
+	play_t	*play = render_ctxt;
+
+	glUniform1f(uniforms[0], alpha);
+	glUniform1f(uniforms[1], play_ticks(play, PLAY_TICKS_TIMER0) * .001f); // FIXME KLUDGE ALERT
+}
+
+
+/* create plasma rendering stage */
+stage_t * plasma_node_new(const stage_conf_t *conf)
+{
+	return	shader_node_new_src(conf, plasma_vs, plasma_fs, NULL, plasma_uniforms, NULL, 2,
+			(const char *[]){
+				"alpha",
+				"time",
+			}
+		);
+}