I tried use “fract(inPosition.y * sample)” to offset vertex , but I failed.
my vert shader like this:
attribute vec3 inPosition;
attribute vec2 inTexCoord;
attribute vec3 inNormal;
uniform float m_Sample;
uniform mat4 g_WorldViewProjectionMatrix;
varying vec2 texCoord;
varying vec3 debug;
void main() {
vec4 modelSpacePos = vec4(inPosition, 1.0);
float sample = 2.;
float dist = fract(inPosition.y * sample);
modelSpacePos.x += dist;
gl_Position = g_WorldViewProjectionMatrix * modelSpacePos;
texCoord = inTexCoord;
}