c# - 如何防止 OpenGL 中的三角形渲染在它们前面的三角形之上

Question

我一直在使用适用于 .NET 的 OpenTK 库来处理 OpenGL，编写我自己的引擎。我放置了 3 个不同的物体，一个旋转的立方体和 2 个相邻的立方体。在我更改对象顶部四边形的颜色之前，一切似乎都运行良好。

我正在渲染顶部为绿色的立方体，在左侧，背面的方 block 被渲染在前面的方 block 之上。我似乎无法找出哪里出了问题，当相机设置为从另一侧看时，它会正确渲染。

以下是类中的相关代码，省略了不相关或不相关的方法、属性和属性:

GameState.cs

class GameState : State
{
    // TEMP: Test Block
    SimpleBlock block;

    int i = 0;
    public override void Render()
    {
        base.Render();

        // Set OpenGL Settings
        GL.Viewport(0, 0, 1024, 768);
        GL.Enable(EnableCap.CullFace);

        // Reset the Matrices
        Matrices.ClearMatrices();

        // Set Camera Settings (Field of view in radians)
        Matrices.ProjectionMatrix = Matrix4.CreatePerspectiveFieldOfView((float)Math.PI / 2, (1024.0f / 768.0f), 1, 1000);

        // Create the Camera
        // this has to be in reverse
        Matrix4 viewMatrix = Matrix4.CreateRotationX((float)Math.PI/8);
        viewMatrix = viewMatrix.Translate(0, -2, -4);

        // Multiply it with the ModelView (Which at this point is set to a value that we can just use = and it has the same result)
        Matrices.ModelViewMatrix = viewMatrix;

        // Render the Block
        Matrices.Push();

        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Translate(2, 0, 0);
        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Translate(0.5f, 0, 0.5f);
        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Rotate(0, i / 40.0f, 0);
        block.Render();

        Matrices.Pop();

        // Render the Block Again Twice
        Matrices.Push();

        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Translate(-2, 0, 0);
        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Translate(0.5f, 0, 0.5f);
        block.Render();

        Matrices.ModelViewMatrix = Matrices.ModelViewMatrix.Translate(0, 0, -1);
        block.Render();

        Matrices.Pop();

        // Increment Rotation Test Variable
        i++;
    }
}

SimpleBlock.cs

class SimpleBlock : IBlock
{
    public void Render()
    {
        // Send the Shader Parameters to the GPU
        Shader.Bind();
        Shader.SendMatrices();

        // Begin Rendering the Polys
        GL.Begin(BeginMode.Triangles);

        // Front Quad
        Shader.SetColor(Color4.SaddleBrown);
        GL.Normal3(0, 0, 1);
        GLUtils.QuadVertices(
            new Vector3(-0.5f, 1, 0.5f),
            new Vector3(-0.5f, 0, 0.5f),
            new Vector3( 0.5f, 1, 0.5f),
            new Vector3( 0.5f, 0, 0.5f));

        // Right Quad
        GL.Normal3(1, 0, 0);
        GLUtils.QuadVertices(
            new Vector3(0.5f, 1,  0.5f),
            new Vector3(0.5f, 0,  0.5f),
            new Vector3(0.5f, 1, -0.5f),
            new Vector3(0.5f, 0, -0.5f));

        // Back Quad
        GL.Normal3(0, 0, -1);
        GLUtils.QuadVertices(
            new Vector3( 0.5f, 1, -0.5f),
            new Vector3( 0.5f, 0, -0.5f),
            new Vector3(-0.5f, 1, -0.5f),
            new Vector3(-0.5f, 0, -0.5f));

        // Left Quad
        GL.Normal3(-1, 0, 0);
        GLUtils.QuadVertices(
            new Vector3(-0.5f, 1, -0.5f),
            new Vector3(-0.5f, 0, -0.5f),
            new Vector3(-0.5f, 1,  0.5f),
            new Vector3(-0.5f, 0,  0.5f));

        // Bottom Quad
        GL.Normal3(0, -1, 0);
        GLUtils.QuadVertices(
            new Vector3(-0.5f, 0,  0.5f),
            new Vector3(-0.5f, 0, -0.5f),
            new Vector3( 0.5f, 0,  0.5f),
            new Vector3( 0.5f, 0, -0.5f));

        // Top Quad
        Shader.SetColor(Color4.Green);
        GL.Normal3(0, 1, 0);
        GLUtils.QuadVertices(
            new Vector3(-0.5f, 1, -0.5f),
            new Vector3(-0.5f, 1, 0.5f),
            new Vector3(0.5f, 1, -0.5f),
            new Vector3(0.5f, 1, 0.5f));

        // Done!
        GL.End();
    }
}

BasicFragment.glfs

#version 130

// MultiColor Attribute
in vec4 multiColor;

// Output color
out vec4 gl_FragColor;

void main()
{
    // Set fragment
    gl_FragColor = multiColor;
}

BasicVertex.glvs

#version 130

// Transformation Matrices
uniform mat4 ProjectionMatrix;
uniform mat4 ModelViewMatrix;

// Vertex Position Attribute
in vec3 VertexPos;

// MultiColor Attributes
in vec4 MultiColor;
out vec4 multiColor;

void main()
{
    // Process Colors
    multiColor = MultiColor;

    // Process Vertex
    gl_Position = ProjectionMatrix * ModelViewMatrix * vec4(VertexPos.x, VertexPos.y, VertexPos.z, 1);
}

MainWindow.cs

// Extends OpenTK's GameWindow Class
class MainWindow : GameWindow
{
    public MainWindow()
        : base(1024, 768, new GraphicsMode(32, 0, 0, 4))
    {
        this.Title = "Trench Wars";
        this.WindowBorder = WindowBorder.Fixed;
        this.ClientSize = new Size(1024, 768);

        // Set VSync On
        this.VSync = VSyncMode.Adaptive;
    }

    protected override void OnRenderFrame(FrameEventArgs e)
    {
        base.OnRenderFrame(e);

        // Clear Screen
        GL.ClearColor(Color4.CornflowerBlue);
        GL.Clear(ClearBufferMask.ColorBufferBit | ClearBufferMask.DepthBufferBit);

        // Do State-Specific Rendering
        StateEngine.Render();

        // Pull a Wicked Bluffing move in Poker
        GL.Flush();

        // Swap Buffers
        this.SwapBuffers();
    }
}

Answer 1

您似乎忘记启用深度测试。 glEnable(GL_DEPTH_TEST) 在渲染几何体之前是你的 friend (或者给定你正在使用的语言绑定(bind) GL.Enable(EnableCap.DepthTest);)。