几天的挣扎后，我来到了这里。我正在尝试根据this教程将自定义每顶点vec3属性传递到自定义着色器中。该教程描述了如何传递自定义uniform，实际上运行良好。但是，当我尝试修改代码以传递我的自定义每顶点属性时，似乎没有东西被传递到顶点着色器中，我无法弄清楚如何使它工作。
在libgdx的自定义着色器的
到目前为止，我已经完成了以下工作：
我使用modelBuilder.createBox()创建了几个盒子（所以我确定每个模型都有24个顶点）
然后，我生成了一个包含实际属性数据的FloatBuffer，如下所示：
int[] data = new int[]{x1, y1, z1, x1, y1, z1, ...}
ByteBuffer byteBuffer = ByteBuffer.allocateDirect(data.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
mAttributeBuffer = byteBuffer.asFloatBuffer();
mAttributeBuffer.put(data);
mAttributeBuffer.position(0);
然后我正在初始化相应的属性位置变量（成功，a_coord >= 0）：
a_coord = program.getAttributeLocation("a_coord");
在libgdx的自定义着色器的
render(Renderable)方法中，我将缓冲区传递给OpenGL，代码如下：program.setVertexAttribute(a_coord, 3, Gdx.gl20.GL_FLOAT, false, 0, mAttributeBuffer);
我的自定义顶点着色器如下：
attribute vec3 a_position;
attribute vec3 a_normal;
attribute vec2 a_texCoord0;
uniform mat4 u_worldTrans;
uniform mat4 u_projTrans;
varying vec2 v_texCoord0;
//my custom attribute
attribute vec2 a_coord;
void main() {
v_texCoord0 = a_texCoord0;
float posY = a_position.y + a_coord.y;
gl_Position = u_projTrans * u_worldTrans * vec4(a_position.x, posY, a_position.z, 1.0);
}
问题
目前每个顶点的 a_coord 都为0。我错过了什么，如何正确地将自定义属性传递给顶点着色器？
我猜问题可能出在 VBO 字段和 libGDX 传递属性数据到顶点的方式上，但我仍然无法弄清楚如何使其正常工作。
如果有人能指导我在这个问题上走向正确方向，我会很高兴。
完整代码：
Main AplicationListener 类:
public class ProtoGame implements ApplicationListener {
public ProtoGame()
{
super();
}
public PerspectiveCamera cam;
public CameraInputController camController;
public Model model;
public Array<ModelInstance> instances = new Array<ModelInstance>();
public ModelBatch modelBatch;
@Override
public void create () {
cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
cam.position.set(0f, 8f, 8f);
cam.lookAt(0,0,0);
cam.near = 1f;
cam.far = 300f;
cam.update();
camController = new CameraInputController(cam);
Gdx.input.setInputProcessor(camController);
ModelBuilder modelBuilder = new ModelBuilder();
model = modelBuilder.createBox(1f, 1f, 1f,
new Material(),
VertexAttributes.Usage.Position | VertexAttributes.Usage.Normal | VertexAttributes.Usage.TextureCoordinates);
Color colorU = new Color(), colorV = new Color();
for (int x = -5; x <= 5; x+=2) {
for (int z = -5; z<=5; z+=2) {
ModelInstance instance = new ModelInstance(model, x, 0, z);
//this is where I'll put per-vertex attribute data for every instance
//but for now it's hardcoded in the Shader class so the data is the same across instances
TestShader.DoubleColorAttribute attr = new TestShader.DoubleColorAttribute(TestShader.DoubleColorAttribute.DiffuseUV,
colorU.set((x+5f)/10f, 1f - (z+5f)/10f, 0, 1),
colorV.set(1f - (x+5f)/10f, 0, (z+5f)/10f, 1));
instance.materials.get(0).set(attr);
instances.add(instance);
}
}
modelBatch = new ModelBatch(new BaseShaderProvider() {
@Override
protected Shader createShader(Renderable renderable) {
return new TestShader();
}
});
}
@Override
public void render () {
camController.update();
Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
Gdx.gl.glClearColor(1, 1, 1, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);
modelBatch.begin(cam);
for (ModelInstance instance : instances)
modelBatch.render(instance);
modelBatch.end();
}
@Override
public void dispose () {
model.dispose();
modelBatch.dispose();
}
}
自定义 libgdx 着色器类：
public class TestShader implements Shader {
private FloatBuffer mAttributeBuffer;
ShaderProgram program;
Camera camera;
RenderContext context;
int u_projTrans;
int u_worldTrans;
int u_colorU;
int u_colorV;
int a_coord;
private static String getCustomVertexShader() {
return Gdx.files.internal("shader/test.vertex.glsl").readString();
}
private static String getCustomFragmentShader() {
return Gdx.files.internal("shader/test.fragment.glsl").readString();
}
@Override
public void init() {
program = new ShaderProgram(getCustomVertexShader(), getCustomFragmentShader());
if (!program.isCompiled())
throw new GdxRuntimeException(program.getLog());
//tutorial's logic to init custom uniform locations
u_projTrans = program.getUniformLocation("u_projTrans");
u_worldTrans = program.getUniformLocation("u_worldTrans");
u_colorU = program.getUniformLocation("u_colorU");
u_colorV = program.getUniformLocation("u_colorV");
//initing custom attribute location
a_coord = program.getAttributeLocation("a_coord");
//generating data and passing it to nio Buffer
float data[] = generateData();
ByteBuffer byteBuffer = ByteBuffer.allocateDirect(data.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
mAttributeBuffer = byteBuffer.asFloatBuffer();
mAttributeBuffer.put(data);
mAttributeBuffer.position(0);
}
private float[] generateData() {
Vector3[] dataArray = new Vector3[1];
dataArray[0] = new Vector3(2, 2, 2);
int components = 3;
int vertexPerModel = 24;
float[] data = new float[dataArray.length * components * vertexPerModel];
for(int i = 0; i < dataArray.length; ++i){
int i3 = i * components;
for(int j = 0; j < vertexPerModel; ++j) {
int j3 = j * components;
data[i3 + 0 + j3] = dataArray[i].x;
data[i3 + 1 + j3] = dataArray[i].y;
data[i3 + 2 + j3] = dataArray[i].z;
}
}
return data;
}
@Override
public void dispose() {
program.dispose();
}
@Override
public void begin(Camera camera, RenderContext context) {
this.camera = camera;
this.context = context;
program.begin();
program.setUniformMatrix(u_projTrans, camera.combined);
context.setDepthTest(GL20.GL_LEQUAL);
context.setCullFace(GL20.GL_BACK);
}
@Override
public void render(Renderable renderable) {
program.setUniformMatrix(u_worldTrans, renderable.worldTransform);
//tutorial's logic to pass uniform
DoubleColorAttribute attribute = ((DoubleColorAttribute) renderable.material.get(DoubleColorAttribute.DiffuseUV));
program.setUniformf(u_colorU, attribute.color1.r, attribute.color1.g, attribute.color1.b);
program.setUniformf(u_colorV, attribute.color2.r, attribute.color2.g, attribute.color2.b);
//passing my custom attributes to the vertex shader
program.setVertexAttribute(a_coord, 3, Gdx.gl20.GL_FLOAT, false, 0, mAttributeBuffer);
renderable.mesh.render(program, renderable.primitiveType,
renderable.meshPartOffset, renderable.meshPartSize);
}
@Override
public void end() {
program.end();
}
@Override
public int compareTo(Shader other) {
return 0;
}
@Override
public boolean canRender(Renderable renderable) {
return renderable.material.has(DoubleColorAttribute.DiffuseUV);
}
}
setVertexAttribute，那样行不通。ModelBuilder（和MeshBuilder）支持自定义属性（只需在构造函数中提供VertexAttributes，而不是方便的位掩码），但在这种情况下，您将不得不修改网格并设置所需的值。 - Xoppa