reorganize to use .bat files instead of .sh. Move demo to an example project

assets/shaders/fragment.glsl

@@ -0,0 +1,16 @@
+#version 330 core
+
+uniform vec4 color;
+
+in vec3 frag_pos;
+
+out vec4 frag_color;
+
+void main() {
+    vec3 dx = dFdx(frag_pos) * 500;
+    vec3 dy = dFdy(frag_pos) * 500;
+    vec3 N = normalize(cross(dFdx(frag_pos), dFdy(frag_pos)));
+    frag_color = color;
+    //frag_color = vec4(length(dx), length(dy), length(dy), 1.0);
+    //frag_color += color;
+}

assets/shaders/vertex.glsl

@@ -0,0 +1,13 @@
+#version 330 core
+
+layout (location = 0) in vec3 pos;
+out vec3 frag_pos;
+
+uniform mat4 global_t;
+uniform mat4 camera_t;
+uniform mat4 projection_t;
+
+void main() {
+    gl_Position = projection_t * camera_t * global_t * vec4(pos.x, pos.y, pos.z, 1.0);
+    frag_pos = pos;
+}