【Defold】UVで回転させるModel用「UVRotate」シェーダー

attribute highp vec4 position;
attribute mediump vec2 texcoord0;
attribute mediump vec3 normal;
uniform mediump mat4 mtx_worldview;
uniform mediump mat4 mtx_view;
uniform mediump mat4 mtx_proj;
uniform mediump mat4 mtx_normal;
 
varying highp vec4 var_position;
varying mediump vec3 var_normal;
varying mediump vec2 var_texcoord0;
 
uniform lowp vec4 _RotateUvAmount;
 
void main()
{
    vec4 p = mtx_worldview * vec4(position.xyz, 1.0);
    var_position = p;
 
    vec2 uvC = texcoord0;
    float cosAngle = cos(_RotateUvAmount.w);
    float sinAngle = sin(_RotateUvAmount.w);
    mat2 rot = mat2(cosAngle, -sinAngle, sinAngle, cosAngle);
    uvC -= vec2(0.5, 0.5);
    var_texcoord0 = rot * uvC;
    var_texcoord0 += vec2(0.5, 0.5);
                                 
    var_normal = normalize((mtx_normal * vec4(normal, 0.0)).xyz);
    gl_Position = mtx_proj * p;       
}

varying highp vec4 var_position;
varying mediump vec3 var_normal;
varying mediump vec2 var_texcoord0;
 
uniform lowp sampler2D tex0;
uniform lowp vec4 tint;
 
void main()
{
    vec4 tint_pm = vec4(tint.xyz * tint.w, tint.w);
    vec4 col = texture2D(tex0, var_texcoord0.xy) * tint_pm;
    gl_FragColor = col;
}

function init(self)
	go.set(msg.url("#model"), "_RotateUvAmount.w", 0.0)
	go.animate(msg.url("#model"), "_RotateUvAmount.w", go.PLAYBACK_LOOP_FORWARD, 6.28, go.EASING_LINEAR, 1.0)
end