3 files changed, 34 insertions, 8 deletions

diff --git a/assets/images/us_flag.png b/assets/images/us_flag.png
new file mode 100644
index 00000000..1545edc2
--- /dev/null
+++ b/assets/images/us_flag.png
diff --git a/assets/shaders/Flag.frag.glsl b/assets/shaders/Flag.frag.glsl
new file mode 100644
index 00000000..79d4bec3
--- /dev/null
+++ b/assets/shaders/Flag.frag.glsl
@@ -0,0 +1,13 @@
+#ifdef GL_ES
+precision highp float;
+#endif
+
+uniform sampler2D u_tex0;
+
+varying vec2 v_uv;
+
+void main(void)
+{
+    vec3 col = texture2D(u_tex0, v_uv).xyz;
+    gl_FragColor = vec4(col,1.0);
+}
\ No newline at end of file
diff --git a/assets/shaders/Flag.vert.glsl b/assets/shaders/Flag.vert.glsl
index 7dc932a7..9da0ee1c 100644
--- a/assets/shaders/Flag.vert.glsl
+++ b/assets/shaders/Flag.vert.glsl
@@ -16,20 +16,33 @@ attribute vec2 texcoord;
 
 // scalar uniforms
 uniform float u_time;
+uniform float u_waveWidth;
+uniform float u_waveHeight;
 
 // matrix uniforms
 uniform mat4 u_mvMatrix;
 uniform mat4 u_projMatrix;
 uniform mat4 u_worldMatrix;
 
+// varying variables
+varying vec2 v_uv;
+
 void main()
 {
-        float angle = (u_time%360)*2;
-
-        a_pos.z  = sin( a_pos.x + angle);
-        a_pos.z += sin( a_pos.y/2 + angle);
-        a_pos.z *= a_pos.x * 0.09;
-        gl_Position = u_projMatrix * u_mvMatrix * vec4(a_pos,1.0) ;
-
-        gl_FragColor = v_color;
+    float pi = 3.14159;
+        float angle = mod(u_time, pi)*2.0;
+
+    vec3 v = a_pos;
+    v_uv = texcoord;
+
+    vec2 pos = texcoord;
+    float tmp = pos.x;  pos.x = pos.y;  pos.y = tmp;
+    pos.x = pos.x * 1.0*pi * u_waveWidth;
+    pos.y = pos.y * 1.0*pi * u_waveWidth;
+
+        v.z  = sin( pos.x + angle);
+        v.z += sin( pos.y/2.0 + angle);
+        v.z *= v.y * 0.09 * u_waveHeight;
+        
+    gl_Position = u_projMatrix * u_mvMatrix * vec4(v,1.0) ;
 }