*: initial implementation of pig

This is nothing to write home about, but it provides a little sandbox for
developing shader-generated textures in the spirit of shadertoy or the
demoscene tool bonzomatic.

It's more oriented towards developing shaders for use with libstage in
the small games I've been hacking on.

1 files changed, 87 insertions, 0 deletions

diff --git a/src/checker-node.c b/src/checker-node.c
new file mode 100644
index 0000000..a17d3f3
--- /dev/null
+++ b/src/checker-node.c
@@ -0,0 +1,87 @@
+/*
+ *  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 "checker-node.h"
+#include "shader-node.h"
+#include "v3f.h"
+
+
+static const char	*checker_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	*checker_fs = ""
+	"#version 120\n"
+
+	"uniform float alpha;"
+	"uniform vec3 color;"
+
+	"void main()"
+	"{"
+	"	int	x = int(mod(gl_TexCoord[0].x * 20, 2));"
+	"	int	y = int(mod(gl_TexCoord[0].y * 20, 2));"
+
+	"	if (x == y) {"
+	"		gl_FragColor = vec4(1.f - color, alpha);"
+	"	} else {"
+	"		gl_FragColor = vec4(.25f * color, alpha);"
+	"	}"
+	"}"
+"";
+
+
+static void checker_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 checker icon rendering stage */
+stage_t * checker_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, checker_vs, checker_fs, model_x, checker_uniforms, (void *)color, 3,
+			(const char *[]){
+				"alpha",
+				"model_x",
+				"color",
+			}
+		);
+}