Hey there! Let's break down what's causing your texture's weird edge and wrap-around issues—it all boils down to how Unity's Texture2D handles pixel coordinates vs. how you're iterating over your pixels.

The Core Problem: Coordinate System Mismatch #

Unity's Texture2D stores pixels in an array where:

• The first row of the array corresponds to the bottom row of the texture (origin at the bottom-left corner).
• Your loop iterates from the top of your texture (y=0) down to the bottom (y=mapHeight-1).

This mismatch flips your texture vertically, causing the "bottom pixels appearing on top" issue. The left/right wrap-around you noticed is likely a visual side effect of this vertical flip messing up your reference, or in your original Perlin Noise code, misaligning noise sampling between adjacent textures.

Fixing the Pixel Indexing #

To fix this, reverse the y-axis when calculating your pixel array index. Instead of using y * mapWidth + x, use (mapHeight - 1 - y) * mapWidth + x—this maps your top-down loop to Unity's bottom-up pixel storage.

Here's the corrected snippet from your GenerateValues method:

public void GenerateValues(Texture2D mapTexture, int posX, int posY)
{
    Color32[] baseColors = new Color32[mapWidth * mapHeight];
    
    for (int y = 0; y < mapHeight; y++)
    {
        for (int x = 0; x < mapWidth; x++)
        {
            bool currentValue = CalculateMapValue(x + posX, y + posY, 100000, 100000);
            // For your test case: currentValue = y > x && x % 2 == 0;
            
            // Reverse the y-axis to match Unity's texture coordinate system
            int textureArrayIndex = (mapHeight - 1 - y) * mapWidth + x;
            baseColors[textureArrayIndex] = currentValue ? Color.black : Color.white;
        }
    }
    
    // Test pixels will now show up in the correct positions
    int testTopLeftIndex = (mapHeight - 1) * mapWidth + 0; // Top-left corner
    baseColors[testTopLeftIndex] = Color.red;
    int testSecondRowIndex = (mapHeight - 2) * mapWidth + 10; // Second row from top, 11th pixel
    baseColors[testSecondRowIndex] = Color.red;
    
    mapTexture.SetPixels32(baseColors);
    mapTexture.Apply();
}

Fixing the Original Perlin Noise Edge Issue #

For your initial Perlin Noise setup, the vertical flip was causing adjacent textures (spawned at different posY positions) to have misaligned noise patterns at their edges. With the corrected indexing, your noise sampling will align properly across all textures, eliminating those edge anomalies.

A quick note on your noise calculation: using large offsets like 100000 is fine, but keep your scaling (*5f) uniform across all textures to maintain seamless noise transitions.

内容的提问来源于stack exchange，提问作者KijeviGombooc