You can, if you know how
This is from one of the shader files in the shaders folder, you can open all of the new Blockland files with notepad
/////////////////////////////////////////////////
// 7x1 gaussian blur fragment shader
/////////////////////////////////////////////////
//varying vec2 v_Coordinates;
uniform vec2 ScaleU;
uniform sampler2D textureSource;
void main()
{
vec4 color = vec4(0.0);
//color += texture2D( textureSource, gl_TexCoord[0].st + vec2( -3.0*ScaleU.x, -3.0*ScaleU.y ) ) * 0.015625;
//color += texture2D( textureSource, gl_TexCoord[0].st + vec2( -2.0*ScaleU.x, -2.0*ScaleU.y ) ) * 0.09375;
color += texture2D( textureSource, gl_TexCoord[0].st + vec2( -1.0*ScaleU.x, -1.0*ScaleU.y ) ) * 0.234375;
color += texture2D( textureSource, gl_TexCoord[0].st + vec2( 0.0 , 0.0) ) * 0.3125;
color += texture2D( textureSource, gl_TexCoord[0].st + vec2( 1.0*ScaleU.x, 1.0*ScaleU.y ) ) * 0.234375;
//color += texture2D( textureSource, gl_TexCoord[0].st + vec2( 2.0*ScaleU.x, 2.0*ScaleU.y ) ) * 0.09375;
//color += texture2D( textureSource, gl_TexCoord[0].st + vec2( 3.0*ScaleU.x, -3.0*ScaleU.y ) ) * 0.015625;
gl_FragColor = color / (0.234375 + 0.3125 + 0.234375);
}