stairs.txt

// xs_begin
// author : @AndyPolygon
// arg : { var = 'height' name = 'step height' value = '1' range = '1 8' step = '1' precision = '0' }
// arg : { var = 'depth' name = 'step depth' value = '1' range = '1 8' step = '1' precision = '0' }
// arg : { var = 'dir' name = 'dir' value = '0' range = '0 3' step = '1' precision = '0' }
// xs_end

//===== built-in args =====
// uniform vec3		i_volume_size;		// volume size [1-256]
// uniform float	i_color_index;		// current color index [0-255]
// uniform int		i_num_color_sels;	// number of color selections [1-255]

//===== built-in functions ===== 
// float voxel( vec3 v );				// get voxel color index
// float color_sel( float k );			// get kth selected color index
// vec4 palette( float index );			// get palette color

//do not mix int and float without implicit conversion for older gpus!!


//minimalist stairs shader!
float map( vec3 v ) 
{
	float z = v.x;
	if (dir == 1.0) z = v.y;
	else if (dir == 2.0) z = (i_volume_size.x - .5) - v.x;
	else if (dir == 3.0) z = (i_volume_size.y - .5) - v.y;

	z /= depth;
	z *= height; 
	z += height;
	return v.z < z ? i_color_index : 0.0;
}