LWJGL中的广告牌

时间:2011-11-23 14:10:06

标签: java opengl 3d lwjgl

我试图使用LWJGL制作一个广告牌,但我成功了。当我进行扫描时,四边形出现并且正面向相机。但是,只要我在任何轴上旋转相机,四边形也会以不同的方式沿着轴移动。这是我使用的代码:

/***************************************************************************************************************************************************************************************************
 * All rendering happens here...
 **************************************************************************************************************************************************************************************************/
private void render() {

    GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer
    GL11.glLoadIdentity(); // Reset The View

    //GL11.glLight(GL11.GL_LIGHT1, GL11.GL_POSITION, lightPosition); // Position The Light

    GL11.glRotatef(360.0f - yrot, 0, 1.0f, 0);
    GL11.glRotatef(lookupdown, 1.0f, 0, 0);

    GL11.glTranslatef(-xpos, 0, -zpos);


    GL11.glCallList(blocksList);
    GL11.glCallList(tilesList);
    GL11.glCallList(roofList);

    /* Render billboards */
    Billboard bb = lvLoader.currentLevel.billboards[0];
    GL11.glPushMatrix();
    GL11.glRotatef(360.0f - yrot, 0, -1.0f, 0);
    GL11.glRotatef(lookupdown, -1.0f, 0, 0);
    GL11.glBegin(GL11.GL_QUADS);
    GL11.glVertex3f(bb.origin.x + 0.5f, bb.origin.y + 0.5f, bb.origin.z);
    GL11.glVertex3f(bb.origin.x - 0.5f, bb.origin.y + 0.5f, bb.origin.z);
    GL11.glVertex3f(bb.origin.x - 0.5f, bb.origin.y - 0.5f, bb.origin.z);
    GL11.glVertex3f(bb.origin.x + 0.5f, bb.origin.y - 0.5f, bb.origin.z);
    GL11.glEnd();
    GL11.glPopMatrix();

以下是控制lookupdown和yrot的函数。

if (Keyboard.isKeyDown(Keyboard.KEY_UP)) { // Is PageUp Being Pressed?
        lookupdown -= 1.0f; // Rotate The Secene Downwards
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_DOWN)) { // Is PageDown Being Pressed?
        lookupdown += 1.0f; // Rotate The Scene Upwards
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_RIGHT))
    {
        yrot -= 1.5f; // Rotate The Scene To The Left
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_LEFT))
    {
        yrot += 1.5f; // Rotate The Scene To The Left
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_W))
    {
        adjustXZ((float) Math.sin(yrot * piover180) * 0.05f, (float) Math.cos(yrot * piover180) * 0.05f, false, false);
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_S))
    {
        adjustXZ((float) Math.sin(yrot * piover180) * 0.05f, (float) Math.cos(yrot * piover180) * 0.05f, true, true);
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_D))
    {
        adjustXZ((float) Math.sin((yrot-90) * piover180) * 0.05f, (float) Math.cos((yrot-90) * piover180) * 0.05f, false, false);
    }

    if (Keyboard.isKeyDown(Keyboard.KEY_A))
    {
        adjustXZ((float) Math.sin((yrot+90) * piover180) * 0.05f, (float) Math.cos((yrot+90) * piover180) * 0.05f, false, false);
    }

private void adjustXZ(float x, float z, boolean xAdd, boolean zAdd)
{
    if (collisionCheck(x, z, xAdd, zAdd))
        return;

    if (xAdd)
        xpos += x;
    else if (!xAdd)
        xpos -= x;

    if (zAdd)
        zpos += z;
    else if (!zAdd)
        zpos -= z;
}

1 个答案:

答案 0 :(得分:0)

我不熟悉LWJGL,所以我不是百分之百地确定它的期望,但根据我对其他3D API的经验,听起来非常像你的矩阵转换顺序错误。

尝试更改代码,如下所示:

GL11.glPushMatrix();
GL11.glTranslatef(bb.origin.x, bb.origin.y, bb.origin.z); // Translation here
GL11.glRotatef(360.0f - yrot, 0, -1.0f, 0);
GL11.glRotatef(lookupdown, -1.0f, 0, 0);
GL11.glBegin(GL11.GL_QUADS);
GL11.glVertex3f(0.5f, 0.5f, 0); // No translation here anymore
GL11.glVertex3f(0.5f, 0.5f, 0;
GL11.glVertex3f(0.5f, 0.5f, 0);
GL11.glVertex3f(0.5f, 0.5f, 0);
GL11.glEnd();

另外,您没有使用传统的广告牌技术。广告牌总是面向相机,而不是让它们始终垂直于相机。对于视图截头边缘附近的广告牌对象,这将是显而易见的。我会让你继续深入研究这个问题!