c# - 在 XNA 4.0 中绘制多边纹理立方体

Question

几个小时以来，我一直在努力解决这个问题。我想做的是画一个立方体，每边都有不同的纹理；或者更具体地说，我希望能够指定每一面我想要的任何纹理。我用了例子 here开始，然后尝试进一步开发它，这样我就可以拥有不止一种纹理。然而，无论我做什么，它仍然只使用应用于效果的最后一个纹理，而不会理会任何先前的分配。这是我的形状类:

public class BasicShape {

 public Vector3 shapeSize;
 public Vector3 shapePosition;
 private VertexPositionNormalTexture[][] shapeVertices;
 private int shapeTriangles;
 private VertexBuffer shapeBuffer;
 public Texture2D topTexture;
 public Texture2D frontTexture;
 public Texture2D backTexture;
 public Texture2D leftTexture;
 public Texture2D rightTexture;
 public Texture2D bottomTexture;

 public BasicShape(Vector3 size, Vector3 position) {
    shapeSize = size;
    shapePosition = position;
 }

 private void BuildShape() {
    shapeTriangles = 12;

    shapeVertices = new VertexPositionNormalTexture[6][];
    for(int i = 0; i < 6; i++) {
        shapeVertices[i] = new VertexPositionNormalTexture[6];
    }

    Vector3 topLeftFront = shapePosition +
     new Vector3(0.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomLeftFront = shapePosition +
     new Vector3(0.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topRightFront = shapePosition +
     new Vector3(1.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomRightFront = shapePosition +
     new Vector3(1.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topLeftBack = shapePosition +
     new Vector3(0.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 topRightBack = shapePosition +
     new Vector3(1.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 bottomLeftBack = shapePosition +
     new Vector3(0.0f, 0.0f, 1.0f) * shapeSize;
    Vector3 bottomRightBack = shapePosition +
     new Vector3(1.0f, 0.0f, 1.0f) * shapeSize;

    Vector3 topLeftFront2 = shapePosition +
     new Vector3(0.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomLeftFront2 = shapePosition +
     new Vector3(0.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topRightFront2 = shapePosition +
     new Vector3(1.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomRightFront2 = shapePosition +
     new Vector3(1.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topLeftBack2 = shapePosition +
     new Vector3(0.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 topRightBack2 = shapePosition +
     new Vector3(1.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 bottomLeftBack2 = shapePosition +
     new Vector3(0.0f, 0.0f, 1.0f) * shapeSize;
    Vector3 bottomRightBack2 = shapePosition +
     new Vector3(1.0f, 0.0f, 1.0f) * shapeSize;

    Vector3 topLeftFront3 = shapePosition +
     new Vector3(0.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomLeftFront3 = shapePosition +
     new Vector3(0.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topRightFront3 = shapePosition +
     new Vector3(1.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomRightFront3 = shapePosition +
     new Vector3(1.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 topLeftBack3 = shapePosition +
     new Vector3(0.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 topRightBack3 = shapePosition +
     new Vector3(1.0f, 1.0f, 1.0f) * shapeSize;
    Vector3 bottomLeftBack3 = shapePosition +
     new Vector3(0.0f, 0.0f, 1.0f) * shapeSize;
    Vector3 bottomRightBack3 = shapePosition +
     new Vector3(1.0f, 0.0f, 1.0f) * shapeSize;

    Vector3 frontNormal = new Vector3(0.0f, 0.0f, 1.0f) * shapeSize;
    Vector3 backNormal = new Vector3(0.0f, 0.0f, -1.0f) * shapeSize;
    Vector3 topNormal = new Vector3(0.0f, 1.0f, 0.0f) * shapeSize;
    Vector3 bottomNormal = new Vector3(0.0f, -1.0f, 0.0f) * shapeSize;
    Vector3 leftNormal = new Vector3(-1.0f, 0.0f, 0.0f) * shapeSize;
    Vector3 rightNormal = new Vector3(1.0f, 0.0f, 0.0f) * shapeSize;

    Vector2 textureTopLeft = new Vector2(1f * shapeSize.X, 0.0f * shapeSize.Y);
    Vector2 textureTopRight = new Vector2(0.0f * shapeSize.X, 0.0f * shapeSize.Y);
    Vector2 textureBottomLeft = new Vector2(1f * shapeSize.X, 1f * shapeSize.Y);
    Vector2 textureBottomRight = new Vector2(0.0f * shapeSize.X, 1f * shapeSize.Y);

    // Front face.
    shapeVertices[0][0] = new VertexPositionNormalTexture(
     topLeftFront, frontNormal, textureTopLeft);
    shapeVertices[0][1] = new VertexPositionNormalTexture(
     bottomLeftFront, frontNormal, textureBottomLeft);
    shapeVertices[0][2] = new VertexPositionNormalTexture(
     topRightFront, frontNormal, textureTopRight);
    shapeVertices[0][3] = new VertexPositionNormalTexture(
     bottomLeftFront, frontNormal, textureBottomLeft);
    shapeVertices[0][4] = new VertexPositionNormalTexture(
     bottomRightFront, frontNormal, textureBottomRight);
    shapeVertices[0][5] = new VertexPositionNormalTexture(
     topRightFront, frontNormal, textureTopRight);

    // Back face.
    shapeVertices[1][0] = new VertexPositionNormalTexture(
     topLeftBack, backNormal, textureTopRight);
    shapeVertices[1][1] = new VertexPositionNormalTexture(
     topRightBack, backNormal, textureTopLeft);
    shapeVertices[1][2] = new VertexPositionNormalTexture(
     bottomLeftBack, backNormal, textureBottomRight);
    shapeVertices[1][3] = new VertexPositionNormalTexture(
     bottomLeftBack, backNormal, textureBottomRight);
    shapeVertices[1][4] = new VertexPositionNormalTexture(
     topRightBack, backNormal, textureTopLeft);
    shapeVertices[1][5] = new VertexPositionNormalTexture(
     bottomRightBack, backNormal, textureBottomLeft);

    // Top face.
    shapeVertices[2][0] = new VertexPositionNormalTexture(
     topLeftFront2, topNormal, textureBottomLeft);
    shapeVertices[2][1] = new VertexPositionNormalTexture(
     topRightBack2, topNormal, textureTopRight);
    shapeVertices[2][2] = new VertexPositionNormalTexture(
     topLeftBack2, topNormal, textureTopLeft);
    shapeVertices[2][3] = new VertexPositionNormalTexture(
     topLeftFront2, topNormal, textureBottomLeft);
    shapeVertices[2][4] = new VertexPositionNormalTexture(
     topRightFront2, topNormal, textureBottomRight);
    shapeVertices[2][5] = new VertexPositionNormalTexture(
     topRightBack2, topNormal, textureTopRight);

    // Bottom face.
    shapeVertices[3][0] = new VertexPositionNormalTexture(
     bottomLeftFront2, bottomNormal, textureTopLeft);
    shapeVertices[3][1] = new VertexPositionNormalTexture(
     bottomLeftBack2, bottomNormal, textureBottomLeft);
    shapeVertices[3][2] = new VertexPositionNormalTexture(
     bottomRightBack2, bottomNormal, textureBottomRight);
    shapeVertices[3][3] = new VertexPositionNormalTexture(
     bottomLeftFront2, bottomNormal, textureTopLeft);
    shapeVertices[3][4] = new VertexPositionNormalTexture(
     bottomRightBack2, bottomNormal, textureBottomRight);
    shapeVertices[3][5] = new VertexPositionNormalTexture(
     bottomRightFront2, bottomNormal, textureTopRight);

    // Left face.
    shapeVertices[4][0] = new VertexPositionNormalTexture(
     topLeftFront3, leftNormal, textureTopRight);
    shapeVertices[4][1] = new VertexPositionNormalTexture(
     bottomLeftBack3, leftNormal, textureBottomLeft);
    shapeVertices[4][2] = new VertexPositionNormalTexture(
     bottomLeftFront3, leftNormal, textureBottomRight);
    shapeVertices[4][3] = new VertexPositionNormalTexture(
     topLeftBack3, leftNormal, textureTopLeft);
    shapeVertices[4][4] = new VertexPositionNormalTexture(
     bottomLeftBack3, leftNormal, textureBottomLeft);
    shapeVertices[4][5] = new VertexPositionNormalTexture(
     topLeftFront3, leftNormal, textureTopRight);

    // Right face.
    shapeVertices[5][0] = new VertexPositionNormalTexture(
     topRightFront3, rightNormal, textureTopLeft);
    shapeVertices[5][1] = new VertexPositionNormalTexture(
     bottomRightFront3, rightNormal, textureBottomLeft);
    shapeVertices[5][2] = new VertexPositionNormalTexture(
     bottomRightBack3, rightNormal, textureBottomRight);
    shapeVertices[5][3] = new VertexPositionNormalTexture(
     topRightBack3, rightNormal, textureTopRight);
    shapeVertices[5][4] = new VertexPositionNormalTexture(
     topRightFront3, rightNormal, textureTopLeft);
    shapeVertices[5][5] = new VertexPositionNormalTexture(
     bottomRightBack3, rightNormal, textureBottomRight);
 }

 public void SetTopTexture(Texture2D tex) {
    topTexture = tex;
 }
 public void SetSideTexture(Texture2D tex) {
    frontTexture = tex;
    backTexture = tex;
    leftTexture = tex;
    rightTexture = tex;
 }
 public void SetBottomTexture(Texture2D tex) {
    bottomTexture = tex;
 }

 public void RenderShape(GraphicsDevice device, Effect effect) {
    BuildShape();


    effect.Parameters["xTexture"].SetValue(topTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[2], 0, 2);
    effect.Parameters["xTexture"].SetValue(bottomTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[3], 0, 2);
    effect.Parameters["xTexture"].SetValue(frontTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[0], 0, 2);
    effect.Parameters["xTexture"].SetValue(backTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[1], 0, 2);
    effect.Parameters["xTexture"].SetValue(leftTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[4], 0, 2);
    effect.Parameters["xTexture"].SetValue(rightTexture);
    device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[5], 0, 2);

 }

在我的游戏的 Draw 方法中:

cubeEffect.CurrentTechnique = cubeEffect.Techniques["Textured"];
   foreach(EffectPass pass in cubeEffect.CurrentTechnique.Passes) {
      pass.Apply();
      BasicShape s = new BasicShape(new Vector3(1, 1, 1), new Vector3(0, 0, 3));
      s.SetTopTexture(TextureLoader.GetTexture(4));
      s.SetSideTexture(TextureLoader.GetTexture(35));
      s.SetBottomTexture(TextureLoader.GetTexture(4));
      s.RenderShape(GraphicsDevice, cubeEffect);   

  }

如你所见，我正在加载不同的纹理，但结果是这样的:

my cube http://www.tinyimg.org/images/769MinecraftClassic_2011_.bmp

我确信纹理是不同的，但在所有面上都绘制了相同的纹理。每一面都需要单独的效果吗？这绝对看起来有点矫枉过正。

Answer 1

在您调用 EffectPass.Apply() 之前，不会应用为效果设置的任何参数。这是因为对效果应用更改的成本很高，您可能希望一次性执行多项更改。

您的 RenderShape 函数应该类似于:

public void RenderShape(GraphicsDevice device, Effect effect)
{
    BuildShape();

    foreach (EffectPass pass in effect.CurrentTechnique.Passes)
    {
        effect.Parameters["xTexture"].SetValue(topTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[2], 0, 2);

        effect.Parameters["xTexture"].SetValue(bottomTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[3], 0, 2);

        effect.Parameters["xTexture"].SetValue(frontTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[0], 0, 2);

        effect.Parameters["xTexture"].SetValue(backTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[1], 0, 2);

        effect.Parameters["xTexture"].SetValue(leftTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[4], 0, 2);

        effect.Parameters["xTexture"].SetValue(rightTexture);
        pass.Apply();
        device.DrawUserPrimitives(PrimitiveType.TriangleList, shapeVertices[5], 0, 2);
    }
}