spritestack.shader

shader_type canvas_item;

uniform sampler2D spritesheet; // Should be a slice image as exported from Magica Voxel
uniform int slice_count = 1; // The number of slices
uniform vec2 camera_vec = vec2( 1., 1. ); // Recomend using (1,1) or (1,1.5)
uniform float camera_ang = 0.0; // change this to change the view angle of the object

const vec2 center = vec2( 0.5 );

bool scale_and_rotate_with_offset( inout vec2 uv, vec2 sxy, float ang, vec2 cent, vec2 offset )
{
	mat2 trmat = mat2( vec2( sxy.x * cos( ang ), -sxy.x * sin( ang ) ), vec2( sxy.y * sin( ang ), sxy.y * cos( ang ) ) );
	uv = trmat * ( uv - cent ) + cent - ( offset * sxy ) * inverse( trmat );
	if( uv.x < 0. || uv.x > 1. || uv.y < 0. || uv.y > 1. ) return false;
	return true;
}

vec4 texture_slice( vec2 uv, int sliceno )
{
	float slice_height_uv = 1. / float( slice_count );
	vec2 sliceuv = uv;
	sliceuv.y *= slice_height_uv;
	sliceuv.y += float( sliceno ) * slice_height_uv;
	return textureLod( spritesheet, sliceuv, 0. );
}

void vertex()
{
	VERTEX *= 4.0;
}
void fragment()
{
	vec2 uvx = UV;//floor( UV / ( TEXTURE_PIXEL_SIZE / 4.0 ) ) * ( TEXTURE_PIXEL_SIZE / 4.0 );
	//uvx.y = floor( uvx.y / ( TEXTURE_PIXEL_SIZE.y / 4.0 ) ) * TEXTURE_PIXEL_SIZE.y / 4.0;
	vec2 uv = ( uvx - vec2( 0.5 ) ) * 4.0 + vec2( 0.5 );
	vec4 c;
	vec2 py = vec2( 0., 1.*TEXTURE_PIXEL_SIZE.y );
	vec2 camera_vec_norm = normalize( camera_vec );
	
	float sliceno = 0.0;
	for( sliceno = 0.0; sliceno < float( slice_count ); sliceno += 0.25 )
	{
		vec2 uv1 = uv;
		if( scale_and_rotate_with_offset( uv1, camera_vec, camera_ang, center, -camera_vec.y * float( sliceno ) * py ) )
		{
			//vec2 pxs = 
			vec4 c1 = texture_slice( uv1, slice_count - int( sliceno ) - 1 );
			if( c1.a > 0. ) c = c1;
		}
	}
	COLOR = c;
}

I fixed GLES2+WebGL exports and SpriteStack.io format compatibility.

https://gist.github.com/greenfox1505/208bac0e7bae4ceed0ec9a1f91346af2