Question

我正在尝试使用OpenGL ES 1.1在我的3D世界中绘制粒子（在2D中）。

3D世界（没有2D粒子）看起来像这样： 3D world without particles

当试图在3D世界中绘制2D粒子时，它看起来像这样（注意网格现在以某种方式移动到左下角）： 3D world attempted with particles

但是，我希望它直接在3D网格上绘制。有关如何实现这一点或为何将其移至左下角的任何想法？

到目前为止我的工作。

- (void)drawFrame
{    
    [(EAGLView *)self.view setFramebuffer];

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

/////////////  3D Drawing the Grid floor

    glDisable(GL_BLEND);
    glDisable(GL_TEXTURE_2D);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    glDepthMask(GL_TRUE);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    static GLfloat z = 0;
    gluLookAt(0, 5, -10, 0, 0, 0, 0, 1, 0);
    z += 0.075f;

    // Rotate the scene
    glRotatef(angle, 0, 1, 0);

    // Draw the Floor
    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
    glDisableClientState(GL_COLOR_ARRAY);
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(3, GL_FLOAT, 0, zFloorVertices);
    glDrawArrays(GL_LINES, 0, 42);
    glVertexPointer(3, GL_FLOAT, 0, xFloorVertices);
    glDrawArrays(GL_LINES, 0, 42);

////////////  2D drawing the particle system

    glMatrixMode(GL_MODELVIEW); 
    glLoadIdentity();
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    glOrthof(0.0f, 320.0f, 0.0f, 480.0f, -100.0f, 100.0f);

    glDisable(GL_DEPTH_TEST);
    glDisable(GL_CULL_FACE);
    glEnable(GL_TEXTURE_2D);
    glEnable(GL_BLEND);

    [explosion1 update:UPDATE_INTERVAL];

    if (explosion1.active != YES)
    {
        explosion1.sourcePosition = Vector2fMake(200, 200);
        explosion1.active = YES;
        explosion1.duration = 1;
        explosion1.sourcePositionVariance = Vector2fMake(0, rand() % 20);
    }

    [explosion1 renderParticles];

    [(EAGLView *)self.view presentFramebuffer];
}

- (void)initOpenGLES1
{
    // Set the clear color
    glClearColor(0, 0, 0, 1.0f);

    // Projection Matrix config
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    CGSize layerSize = self.view.layer.frame.size;
    gluPerspective(45.0f, (GLfloat)layerSize.width / (GLfloat)layerSize.height, 0.1f, 750.0f);

    // Modelview Matrix config
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    // This next line is not really needed as it is the default for OpenGL ES
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glDisable(GL_BLEND);

    // Enable depth testing
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    glDepthMask(GL_TRUE);
}

Answer 1

想出来，不得不重置3D渲染的gluPerspective。

// 3D
glMatrixMode(GL_PROJECTION);
glLoadIdentity();

CGSize layerSize = self.view.layer.frame.size;
gluPerspective(45.0f, (GLfloat)layerSize.width / (GLfloat)layerSize.height, 0.1f, 750.0f);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity(); //gets rid of any rotations, movement, or other changes to the virtual world and puts us back at the origin standing upright

....

如何在3D世界中绘制2D对象

1 个答案: