spriteAnimation in particle

fragmentShader.fs

uniform vec2 spriteLength;
uniform sampler2D texture;

varying float progress;

void main() {

	vec2 texCoord = vec2(
		gl_PointCoord.x / spriteLength.x + 1. / spriteLength.x * floor( spriteLength.x * progress * spriteLength.y ),
		1. - ( gl_PointCoord.y / spriteLength.y + 1. / spriteLength.y * floor( spriteLength.y * progress ) )
	);

	gl_FragColor = texture2D( texture, vec2( texCoord ) );

}