libgdx: SpriteBatch not displayed with PerspectiveCamera

Question

While I do have the basic knowledge of OpenGL I'm just starting with libgdx.

My question is: why, having the exact same code but only switching from OrthographicCamera to PerspectiveCamera has the effect of no longer displaying any of my SpriteBatches ?

Here's the code I use:

the create() method:

public void create() {
    textureMesh = new Texture(Gdx.files.internal("data/texMeshTest.png"));
    textureSpriteBatch = new Texture(Gdx.files.internal("data/texSpriteBatchTest.png"));

    squareMesh = new Mesh(true, 4, 4, 
            new VertexAttribute(Usage.Position, 3, "a_position")
            ,new VertexAttribute(Usage.TextureCoordinates, 2, "a_texCoords")

    );

    squareMesh.setVertices(new float[] {
            squareXInitial, squareYInitial, squareZInitial,             0,1,    //lower left
            squareXInitial+squareSize, squareYInitial, squareZInitial,  1,1,    //lower right
            squareXInitial, squareYInitial+squareSize, squareZInitial,  0,0,    //upper left
            squareXInitial+squareSize, squareYInitial+squareSize, squareZInitial,1,0});  //upper right 

    squareMesh.setIndices(new short[] { 0, 1, 2, 3});

    spriteBatch = new SpriteBatch();        
}

and the render() method:

public void render() {
    GLCommon gl = Gdx.gl;

    camera.update();
    camera.apply(Gdx.gl10);
    spriteBatch.setProjectionMatrix(camera.combined);

    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
    gl.glEnable(GL10.GL_DEPTH_TEST);

    gl.glEnable(GL10.GL_TEXTURE_2D);
    textureMesh.bind();
    squareMesh.render(GL10.GL_TRIANGLE_STRIP, 0, 4);

    spriteBatch.begin();
    spriteBatch.draw(textureSpriteBatch, -10, 0);
    spriteBatch.end();        
}

Now, if in my resize(int width, int height) method I setup the camera like so:

   public void resize(int width, int height) {
        float aspectRatio = (float) width / (float) height;
        camera = new OrthographicCamera(cameraViewHeight * aspectRatio, cameraViewHeight);

I get this:

enter image description here

But if I change the camera type:

public void resize(int width, int height) {
    float aspectRatio = (float) width / (float) height;
    camera = new PerspectiveCamera(64, cameraViewHeight * aspectRatio, cameraViewHeight);
}

I get this:

enter image description here

The reason I'm asking is because I really liked libgdx's built in ability to draw text (font) in OpenGL. But in their examples they use a SpriteBatch which they path to the Font instance, and they also always use Ortho Camera. I'd like to know then if SpriteBatch and Font drawing functionality work with PerspectiveCamera.

When using the PerspectiveCamera I think the [Decal](http://code.google.com/p/libgdx-users/wiki/Decals) and DecalBatch classes are what the libgdx authors intended us to use. — Sundae, Jul 05 '12 at 21:59
The code contains too long lines (scrolling code horizontally is not cool) (also in the answer) — Display Name, Mar 09 '14 at 18:39
by the way, I guess you can simply use 2 cameras — all they do is hiding "scary" matrix calculations behind "simple" abstractions. — Display Name, Mar 09 '14 at 18:41

score 4 · Accepted Answer · answered Mar 09 '12 at 13:08

Well, ok, I solved it:

Short answer:

SpriteBatch uses an OrthogonalPerspective internally. If you use PerspectiveCamera you need to pass a custom view matrix to the SpriteBatch. You can do that in the resize(...) method:

@Override
public void resize(int width, int height) {
    float aspectRatio = (float) width / (float) height;
    camera = new PerspectiveCamera(64, cameraViewHeight * aspectRatio, cameraViewHeight);
    viewMatrix = new Matrix4();
    viewMatrix.setToOrtho2D(0, 0,width, height);
    spriteBatch.setProjectionMatrix(viewMatrix);
}

And then there's no need to do anything else with that sprite's projection matrix (unless you want to change how the sprite is displayed on screen):

public void render() {
    GLCommon gl = Gdx.gl;

    camera.update();
    camera.apply(Gdx.gl10);
    //this is no longer needed:
    //spriteBatch.setProjectionMatrix(camera.combined);
    //...

Long answer: since my final goal was to be able to use a SpriteBatch to draw text, while with the above mentioned modification to my code I can do that, in the sense that both the text on the sprite and the mesh with the texture are now visible, I've noticed that if I don't specify a color for the vertices of my mesh, said vertices will get the color I use for the text. In other words, with a textured mesh declared like so:

 squareMesh = new Mesh(true, 4, 4, 
            new VertexAttribute(Usage.Position, 3, "a_position")
            ,new VertexAttribute(Usage.TextureCoordinates, 2, "a_texCoords")

    );

    squareMesh.setVertices(new float[] {
            squareXInitial, squareYInitial, squareZInitial,             0,1,    //lower left
            squareXInitial+squareSize, squareYInitial, squareZInitial,  1,1,    //lower right
            squareXInitial, squareYInitial+squareSize, squareZInitial,  0,0,    //upper left
            squareXInitial+squareSize, squareYInitial+squareSize, squareZInitial,1,0});  //upper right 

    squareMesh.setIndices(new short[] { 0, 1, 2, 3});

also having this code in my render(...) method will make the mesh red-tinted:

font.setColor(Color.RED);
spriteBatch.draw(textureSpriteBatch, 0, 0);
font.draw(spriteBatch, (int)fps+" fps", 0, 100);

The fix to this is to set colors on your mesh's vertices right from the start:

squareMesh = new Mesh(true, 4, 4, 
        new VertexAttribute(Usage.Position, 3, "a_position")
        ,new VertexAttribute(Usage.ColorPacked, 4, "a_color")
        ,new VertexAttribute(Usage.TextureCoordinates, 2, "a_texCoords")

);

squareMesh.setVertices(new float[] {
        squareXInitial, squareYInitial, squareZInitial,                         Color.toFloatBits(255, 255, 255, 255),  0,1,    //lower left
        squareXInitial+squareSize, squareYInitial, squareZInitial,              Color.toFloatBits(255, 255, 255, 255),  1,1,    //lower right
        squareXInitial, squareYInitial+squareSize, squareZInitial,              Color.toFloatBits(255, 255, 255, 255),  0,0,    //upper left
        squareXInitial+squareSize, squareYInitial+squareSize, squareZInitial,   Color.toFloatBits(255, 255, 255, 255),  1,0});  //upper right 

squareMesh.setIndices(new short[] { 0, 1, 2, 3});

libgdx: SpriteBatch not displayed with PerspectiveCamera

1 Answers1