I've implemented a terrain in my application and I wanted to use several textures to render it with. I found a tutorial on the web http://www.mbsoftworks.sk/index.php?page=tutorials&series=1&tutorial=24 which used 3 textures and transitioned between them.

I've got everything working except that i get weird lines on the heights that the mixing occurs.

What could be the cause of this?

I've attached an image showing the problem

Can you show your shader code?

Cheers!

Possibly need a slight offset to your texCoords? Or maybe mipmapping is causing it?

Oh yes sorry, here it is:

#version 330

out vec4 out_Color;
uniform sampler2D sandTexture;
uniform sampler2D grassTexture;
uniform sampler2D rockTexture;

uniform float TerrainHeight;

//From vertex shader
in vec2 texCoord;
in vec3 normal;
in vec3 position;

vec4 texColor = vec4(0);
float shade;

void main(void)
{
	const vec3 light = vec3(0.5, 1, 0.5);
        shade = dot(light, normalize(normal));

	const float fRange1 = 0.01f;
	const float fRange2 = 0.1f;
	const float fRange3 = 0.5f;
	const float fRange4 = 0.9f;

	float fScale = position.y/TerrainHeight;
	if(fScale >= 0.0 && fScale <= fRange1)
		texColor = texture(sandTexture, texCoord);
	else if(fScale <= fRange2) 
	{
		fScale -= fRange1; 
		fScale /= (fRange2-fRange1); 
     
		float fScale2 = fScale; 
		fScale = 1.0-fScale;  
     
		texColor += texture(sandTexture, texCoord)*fScale; 
		texColor += texture(grassTexture, texCoord)*fScale2; 
	}
	else if(fScale <= fRange3)
		texColor = texture(grassTexture, texCoord);
	else if(fScale <= fRange4) 
	{ 
		fScale -= fRange3; 
		fScale /= (fRange4-fRange3); 
 
		float fScale2 = fScale; 
		fScale = 1.0-fScale;
 
		texColor += texture(grassTexture, texCoord)*fScale;
		texColor += texture(rockTexture, texCoord)*fScale2;
	}
	else
		texColor = texture(rockTexture, texCoord);

	out_Color = texColor * shade;
}

Basically its the same as the fragment shader in the tutorial

They look like stitching artefacts to me, not a texturing problem. Are they running north to south, and east to west?

How are you rendering your terrain?

The problem don't occur when i use a single texture or when just coloring the terrain

Yeah I see where the problem occurs, but I dont understand why.