LWJGL为什么有时我的几何图形渲染不正确？

Question

I've made a simple opengl application in java, using LWJGL and GLFW. I created a class for rendering a textured box. It creates the vertex positions, texture coordinates, and uses a VBO. The box is rendered using GL_TRIANGLES . When I start the program to test it, sometimes: - The output is correct, I see the box rendered correctly. - There's very big, weird (white/gray) triangle sticking out of the box. - The box is totally deformed, like there are a lot of triangles totally random.

When I don't change any code, the result is still different every time. But sometimes the box is rendered correctly.

I'm quite sure my vertices and texture coordinates are correct. It's hard to find what's wrong. I recreated the box class so it renders it using GL_QUADS (and of course rethought the vertex/texture coordinates). But then I still get the same weird behaviour.

The hard thing is that the result is different every time the program runs, while the code isn't edited.

Here some pictures, one of a run where it's all correct:

And now I run the program again, and I get this:

And so on...

Does someone know what could be happening? This is how I render the box:

texture.bind();

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glEnable(GL_TEXTURE_2D);

glBindBuffer(GL_ARRAY_BUFFER, vboId);
glVertexPointer(3, GL_FLOAT, 0, 0);

glBindBuffer(GL_ARRAY_BUFFER, texId);
glTexCoordPointer(2, GL_FLOAT, 0, 0);

glDrawArrays(GL_TRIANGLES, 0, vertices.length);

glDisableClientState(GL_VERTEX_ARRAY);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisable(GL_TEXTURE_2D);

Texture.unbind();

It already could help if someone knows what causes the changing result.

The code of my box class:

package shapes;

import static org.lwjgl.opengl.GL11.GL_FLOAT;
import static org.lwjgl.opengl.GL11.GL_TEXTURE_2D;
import static org.lwjgl.opengl.GL11.GL_TEXTURE_COORD_ARRAY;
import static org.lwjgl.opengl.GL11.GL_TRIANGLES;
import static org.lwjgl.opengl.GL11.GL_VERTEX_ARRAY;
import static org.lwjgl.opengl.GL11.glDisable;
import static org.lwjgl.opengl.GL11.glDisableClientState;
import static org.lwjgl.opengl.GL11.glDrawArrays;
import static org.lwjgl.opengl.GL11.glEnable;
import static org.lwjgl.opengl.GL11.glEnableClientState;
import static org.lwjgl.opengl.GL11.glTexCoordPointer;
import static org.lwjgl.opengl.GL11.glVertexPointer;
import static org.lwjgl.opengl.GL15.GL_ARRAY_BUFFER;
import static org.lwjgl.opengl.GL15.GL_STATIC_DRAW;
import static org.lwjgl.opengl.GL15.glBindBuffer;
import static org.lwjgl.opengl.GL15.glBufferData;
import static org.lwjgl.opengl.GL15.glGenBuffers;

import java.nio.FloatBuffer;

import main.Geometry;

import org.lwjgl.BufferUtils;

import textures.Texture;

public class TriangleBox extends Geometry {

    private float sizeX;
    private float sizeY;
    private float sizeZ;

    private short[] indices;
    private float[] texCoords;

    private int vboId;
    private int texId;
    private int indId;

    private Texture texture;

    /**
     * Creates a beam figure (a bar)
     * 
     * @param widthX
     * @param heightY
     * @param depthZ
     */
    public TriangleBox(float widthX, float heightY, float depthZ, Texture tex) {

        this.sizeX = widthX;
        this.sizeY = heightY;
        this.sizeZ = depthZ;

        this.setTexture(tex);
        this.createVertices();
        this.createVBO();
    }

    public void setTexture(Texture tex) {

        this.texture = tex;
    }

    protected void createVertices() {

        vertices = new float[] { 
                //Bottom
                0, 0, 0,    
                1, 0, 0,    
                0, 0, 1,    

                0, 0, 1,    
                1, 0, 0,    
                1, 0, 1,    

                //Top
                0, 1, 0,    
                1, 1, 0,    
                0, 1, 1,    

                0, 1, 1,    
                1, 1, 0,    
                1, 1, 1,    

                //Front
                0, 1, 1,    
                1, 1, 1,    
                0, 0, 1,    

                0, 0, 1,    
                1, 1, 1,    
                1, 0, 1,    

                //Back
                1, 1, 0,    
                0, 1, 0,    
                1, 0, 0,    

                1, 0, 0,    
                0, 1, 0,    
                0, 0, 0,    

                //Left
                0, 1, 0,    
                0, 1, 1,    
                0, 0, 0,    

                0, 0, 0,    
                0, 1, 1,
                0, 0, 1,

                //Right
                1, 1, 1,
                1, 1, 0,
                1, 0, 1,

                1, 0, 1,
                1, 1, 0,
                1, 0, 0,
        };

        texCoords = new float[] { 
                // Bottom
                0f,     .33f,
                .25f,   .33f,
                0f,     .66f,

                0f,     .66f,
                .25f,   .33f,
                .25f,   .66f,

                // Top
                .75f,   .33f,
                .50f,   .33f,
                .75f,   .66f,

                .75f,   .66f,
                .50f,   .33f,
                .50f,   .66f,

                // Front  
                0f,     1f  ,
                .25f,   1f  ,
                0f,     .66f,

                0f,     .66f,
                .25f,   1f  ,
                .25f,   .66f,

                // Back
                .25f,   0f  ,
                0f,     0f  ,
                .25f,   .33f,

                .25f,   .33f,
                0f,     0f  ,
                0f,     .33f,

                // Left
                .75f,   .33f,
                .75f,   .66f,
                1f,     .33f,

                1f,     .33f,
                .75f,   .66f,
                1f,     .66f,

                // Right
                .50f,   .66f,
                .50f,   .33f,
                .25f,   .66f,

                .25f,   .66f,
                .50f,   .33f,
                .25f,   .33f
        };
    }

    public void createVBO() {

        FloatBuffer vertexBuffer = BufferUtils.createFloatBuffer(vertices.length);
        vertexBuffer.put(vertices);
        vertexBuffer.flip();

        FloatBuffer texCoordBuffer = BufferUtils.createFloatBuffer(texCoords.length);
        texCoordBuffer.put(texCoords);
        texCoordBuffer.flip();

        vboId = glGenBuffers();
        glBindBuffer(GL_ARRAY_BUFFER, vboId);
        glBufferData(GL_ARRAY_BUFFER, vertexBuffer, GL_STATIC_DRAW);

        texId = glGenBuffers();
        glBindBuffer(GL_ARRAY_BUFFER, texId);
        glBufferData(GL_ARRAY_BUFFER, texCoordBuffer, GL_STATIC_DRAW);

        glBindBuffer(GL_ARRAY_BUFFER, 0);
    }

    public void render() {

        texture.bind();

        glEnableClientState(GL_VERTEX_ARRAY);
        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
        glEnable(GL_TEXTURE_2D);

        glBindBuffer(GL_ARRAY_BUFFER, vboId);
        glVertexPointer(3, GL_FLOAT, 0, 0);

        glBindBuffer(GL_ARRAY_BUFFER, texId);
        glTexCoordPointer(2, GL_FLOAT, 0, 0);

        glDrawArrays(GL_TRIANGLES, 0, vertices.length);

        glDisableClientState(GL_VERTEX_ARRAY);
        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
        glDisable(GL_TEXTURE_2D);

        Texture.unbind();
    }
}

Vertex shader:

#version 120

attribute vec3 position;

void main() {

    gl_Position = vec4(position.x, position.y, position.z, 1.0);
}

Fragment shader

#version 120

void main() {

    gl_FragColor = gl_Color; //vec4(0.1, 1.0, 1.0, 1.0);
}

Answer 1

Since in the pictures you show the box from different angles, my best guess would still be, there is something wrong with the vertices. So maybe you dont get different results everytime you run it, but actually only see the same result from different angles, which makes the object appear differently because of faceculling or other reasons.

Try rendering a quad (easier to determin right vertices) and see if you still get the same result.