How to make image rotation look clean? Android GL ES

Question

I am reading the book called beginning android games.

In the book it has the following method in the SpriteBatcher class...

public void drawSprite(float x, float y, float width, float height, float angle, TextureRegion region) {
    float halfWidth = width / 2;
    float halfHeight = height / 2;

    float rad = angle * Vector2.TO_RADIANS;
    float cos = FloatMath.cos(rad);
    float sin = FloatMath.sin(rad);

    float x1 = -halfWidth * cos - (-halfHeight) * sin;
    float y1 = -halfWidth * sin + (-halfHeight) * cos;
    float x2 = halfWidth * cos - (-halfHeight) * sin;
    float y2 = halfWidth * sin + (-halfHeight) * cos;
    float x3 = halfWidth * cos - halfHeight * sin;
    float y3 = halfWidth * sin + halfHeight * cos;
    float x4 = -halfWidth * cos - halfHeight * sin;
    float y4 = -halfWidth * sin + halfHeight * cos;

    x1 += x;
    y1 += y;
    x2 += x;
    y2 += y;
    x3 += x;
    y3 += y;
    x4 += x;
    y4 += y;

    verticesBuffer[bufferIndex++] = x1;
    verticesBuffer[bufferIndex++] = y1;
    verticesBuffer[bufferIndex++] = region.u1;
    verticesBuffer[bufferIndex++] = region.v2;

    verticesBuffer[bufferIndex++] = x2;
    verticesBuffer[bufferIndex++] = y2;
    verticesBuffer[bufferIndex++] = region.u2;
    verticesBuffer[bufferIndex++] = region.v2;

    verticesBuffer[bufferIndex++] = x3;
    verticesBuffer[bufferIndex++] = y3;
    verticesBuffer[bufferIndex++] = region.u2;
    verticesBuffer[bufferIndex++] = region.v1;

    verticesBuffer[bufferIndex++] = x4;
    verticesBuffer[bufferIndex++] = y4;
    verticesBuffer[bufferIndex++] = region.u1;
    verticesBuffer[bufferIndex++] = region.v1;

    numSprites++;
}

My question is how do you rotate an image like the one below smoothly so that the lines in the image don't look pixelated?

I do have the image at the right size and DPI and looks great before its rotated, but when it is rotated the edges of the lines don't look so great.

Answer 1

You could try using LINEAR sampling instead of NEAREST, though it's hard for me to guess more without seeing a picture of the problem, or seeing your texture creation code.