要回答这个问题需要大量的解释和代码。我首先从代码开始：
LibGDX 代码：
public class Test extends Game {
private final FPSLogger fpsLogger = new FPSLogger();
private ShaderProgram shader;
private Mesh mesh;
Matrix4 projection = new Matrix4();
Matrix4 view = new Matrix4();
Matrix4 model = new Matrix4();
Matrix4 combined = new Matrix4();
Matrix4 modelView = new Matrix4();
Matrix3 normalMatrix = new Matrix3();
Vector3 axis = new Vector3(1, 0, 1).nor();
float angle = 45;
private static final float[] light = { 20, 20, 20 };
private static final float[] amb = { 0.2f, 0.2f, 0.2f, 1.0f };
private static final float[] dif = { 0.5f, 0.5f, 0.5f, 1.0f };
private static final float[] spec = { 0.7f, 0.7f, 0.7f, 1.0f };
public Test() {}
@Override public void create() {
this.mesh = Shapes.genCube();
ShaderProgram.pedantic = false;
final String location = "shaders/phong";
this.shader = new ShaderProgram(Gdx.files.internal(location + ".vsh").readString(), Gdx.files.internal(location + ".fsh").readString());
if (!this.shader.isCompiled()) {
Gdx.app.log("Problem loading shader:", this.shader.getLog());
}
Gdx.gl20.glEnable(GL20.GL_DEPTH_TEST);
}
@Override public void render() {
super.render();
this.fpsLogger.log();
this.angle += Gdx.graphics.getDeltaTime() * 40.0f;
final float aspect = Gdx.graphics.getWidth() / (float) Gdx.graphics.getHeight();
this.projection.setToProjection(1.0f, 20.0f, 60.0f, aspect);
this.view.idt().trn(0, 0, -2.0f);
this.model.setToRotation(this.axis, this.angle);
this.combined.set(this.projection).mul(this.view).mul(this.model);
this.modelView.set(this.view).mul(this.model);
Gdx.gl20.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
Gdx.gl20.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);
this.shader.begin();
this.shader.setUniformMatrix("mvpMatrix", this.combined);
this.shader.setUniformMatrix("mvMatrix", this.modelView);
this.shader.setUniformMatrix("normalMatrix", this.normalMatrix.set(this.modelView).inv().transpose());
this.shader.setUniform4fv("ambientColor", amb, 0, 4);
this.shader.setUniform4fv("diffuseColor", dif, 0, 4);
this.shader.setUniform4fv("specularColor", spec, 0, 4);
this.shader.setUniform3fv("vLightPosition", light, 0, 3);
this.mesh.render(this.shader, GL20.GL_TRIANGLES);
this.shader.end();
}
@Override public void dispose() {
if (this.mesh != null) {
this.mesh.dispose();
}
if (this.shader != null) {
this.shader.dispose();
}
}
}
顶点着色器 (phong.vsh)
attribute vec3 a_position;
attribute vec3 a_normal;
uniform mat4 mvpMatrix; // mvp = ModelViewProjection
uniform mat4 mvMatrix; // mv = ModelView
uniform mat3 normalMatrix;
uniform vec3 vLightPosition;
varying vec3 vVaryingNormal;
varying vec3 vVaryingLightDir;
void main(void) {
vVaryingNormal = normalMatrix * a_normal;
vec4 vPosValue = vec4(a_position.x, a_position.y, a_position.z, 1.0);
vec4 vPosition4 = mvMatrix * vPosValue;
vec3 vPosition3 = a_position;
vVaryingLightDir = normalize(vLightPosition - vPosition3);
gl_Position = mvpMatrix * vPosValue;
}
片段着色器 (phong.fsh)
#ifdef GL_ES
precision mediump float;
#endif
uniform vec4 ambientColor;
uniform vec4 diffuseColor;
uniform vec4 specularColor;
varying vec3 vVaryingNormal;
varying vec3 vVaryingLightDir;
void main(void) {
float diff = max(0.0, dot(normalize(vVaryingNormal), normalize(vVaryingLightDir)));
vec4 color = diff * diffuseColor;
color += ambientColor;
vec3 vReflection = normalize(reflect(-normalize(vVaryingLightDir),normalize(vVaryingNormal)));
float spec = max(0.0, dot(normalize(vVaryingNormal), vReflection));
if(diff != 0) {
float fSpec = pow(spec, 128.0);
color.rgb += vec3(fSpec, fSpec, fSpec);
}
gl_FragColor = color;
}
解释：
它看起来不像一个非常好的 Phong 着色器，因为立方体的法线没有正确计算。您可以在 Shapes.genCube() 内部找到它，但我会将其留给您修复，因为我已经提供了其他所有内容。
确保检查着色器代码，这是 OpenGL ES 2.0 GLSL，它与您发布的 OpenGL 3.3 GLSL 不同。这些是版本之间的一些差异。
您需要做的是确保为着色器提供的值与着色器的变量匹配。您还需要确保正确设置矩阵并为灯光提供正确的值，以便其正确显示。
