I am working on a voxel engine and I'm trying to texture my terrain but I get very strange artifacts.
I lookup the texture coords depending on the worldposition, the relevant line of my shader code is
vec3 vtex = mod(my_vWorldPosition.xzy,64.0)/64.0;
It seems whenever worldpos.xyz/64.0 is 0 the artifacts appear, if I offset the position by 0.0001 they are gone.
I think its because of a precisson loss or something, how can I overcome this?
Here is a pic how it looks like:
Can you post the rest of your shader code? My first guess would be that you have a divide-by-zero (or similarly undefined mathematical construct) later in the same shader.
vertexshader
attribute vec3 position;
uniform sampler2D texture_0;
varying vec3 my_vWorldPosition;
void main() {
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
gl_Position = projectionMatrix * mvPosition;
my_vWorldPosition = (modelMatrix * vec4( position, 1.0 )).xyz;
}fragmentshader
uniform sampler2D texture_0;
varying vec3 my_vWorldPosition;
vec2 computeSliceOffset(float slice, float slicesPerRow, vec2 sliceSize) {
return sliceSize * vec2(mod(slice, slicesPerRow),floor(slice / slicesPerRow));
}
vec4 sampleAs3DTexture(sampler2D tex, vec3 texCoord, float size, float numRows, float slicesPerRow) {
float slice = texCoord.z * size;
float sliceZ = floor(slice);
float zOffset = fract(slice);
vec2 sliceSize = vec2(1.0 / slicesPerRow, // u space of 1 slice
1.0 / numRows); // v space of 1 slice
vec2 slice0Offset = computeSliceOffset(sliceZ, slicesPerRow, sliceSize);
vec2 slice1Offset = computeSliceOffset(sliceZ + 1.0, slicesPerRow, sliceSize);
vec2 slicePixelSize = sliceSize / size; // space of 1 pixel
vec2 sliceInnerSize = slicePixelSize * (size - 1.0); // space of size pixels
vec2 uv = slicePixelSize * 0.5 + texCoord.xy * sliceInnerSize;
vec4 slice0Color = texture2D(tex, slice0Offset + uv);
vec4 slice1Color = texture2D(tex, slice1Offset + uv);
//return mix(slice0Color, slice1Color, zOffset);
return slice0Color;
}
void main() {
vec3 vtex = mod(my_vWorldPosition.xzy,64.0)/64.0;
gl_FragColor = sampleAs3DTexture(texture_0,vtex,64.0,8.0,8.0);
}
