首先来看看效果：
原理：分为两部分，上面的是线条，下面是多边形， 所以需要两个Mesh（点的数据就是随便模拟了几个）
1.地下部分
地下部分
原理：根据顶点数据+底部的点组成一些列的点 这些点放入Mesh画出来。
points.add(new Vector2(114, 240));
//points.add(new Vector2(800, 240));
points.add(new Vector2(268, 434));
points.add(new Vector2(400, 450));
points.add(new Vector2(626, 257));
points.add(new Vector2(921, 244));
linepoints.addAll(points);
stage.addActor(new GroundActor(points));
下面来GroundActor的写法
1.定义shader
ShaderProgram shader;
shader = new ShaderProgram(Gdx.files.internal("surface_vertex.gles"), Gdx.files.internal ("surface_fragment.gles"));
surface_vertex.gles
attribute vec4 a_position;
attribute vec4 a_color;
attribute vec2 a_texCoord0;
uniform mat4 u_worldView;
varying vec4 v_color;
varying vec2 v_texCoords;
void main()
{
v_color = vec4(1, 1, 1, 1);
gl_Position = u_worldView * a_position;
v_texCoords = a_texCoord0;
}
surface_fragment.gles
#ifdef GL_ES
precision mediump float;
#endif
varying vec2 v_texCoords;
uniform sampler2D u_texture;
varying vec4 v_color;
void main(){
gl_FragColor = v_color * texture2D(u_texture, v_texCoords);
}
2.定义mesh
Mesh mesh;
mesh = new Mesh(true, points.size * 2, points.size * 2,
new VertexAttribute(VertexAttributes.Usage.Position, 2, "a_position"),
new VertexAttribute(VertexAttributes.Usage.TextureCoordinates, 2, "a_texCoord0"));
3.定义Texture
private final Texture texture;
texture = new Texture("tile.png");
texture.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear);
texture.setWrap(Texture.TextureWrap.Repeat, Texture.TextureWrap.Repeat);
4.解析顶点数据
//每个顶点需要占4个位置， 点坐标2个，纹理坐标2个，根据上面的顶点生成一个相应的底部顶点
//总共需要points.size * 2个顶点， 每个顶点占4个位置
float vertexs[] = new float[2 * 2 * 2 * points.size];
int offset = 0;
for (Vector2 point : points){
//下面的顶点 比如顶点2
vertexs[offset + 0] = point.x; //横坐标
vertexs[offset + 1] = 0; //纵坐标，顶部的点Y都是0
vertexs[offset + 2] = point.x / texture.getWidth(); //纹理坐标，横轴
vertexs[offset + 3] = 0; //纹理坐标
//上面的顶点 比如1
vertexs[offset + 4] = point.x;
vertexs[offset + 5] = point.y;
vertexs[offset + 6] = point.x / texture.getWidth();
vertexs[offset + 7] = point.y / texture.getHeight();
offset += 8;
}
//设置顶点数据到mesh中
mesh.setVertices(vertexs);
short[] indices1 = new short[points.size * 2];
for (int i = 0; i < indices1.length; i++){
indices1[i] = (short) i;
}
//设置索引，就是依顺序0,1,2,3,4,5,6,7,8,9...
mesh.setIndices(indices1);
5.把Mesh画出来
Gdx.gl.glEnable(GL20.GL_BLEND);
Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
//把stage的相机绑定在mesh上
shader.begin();shader.setUniformMatrix("u_worldView", getStage().getCamera().combined);texture.bind(0);
mesh.render(shader, GL20.GL_TRIANGLE_STRIP);
shader.end();
Gdx.gl.glDisable(GL20.GL_BLEND);
至此底部的地形就画出来了，剩下的就是上面部分
Paste_Image.png
这部分原理差不多，只是生成点的方式不一样而已
Paste_Image.png
只需要生成顶点的时候上移和下移一下就好了。
int offset = 0;
Vector2 pt = new Vector2();
for (int i = 0; i < points.size; ++i){
pt.set(points.get(i).cpy());
vertexs[offset + 0] = pt.x;
vertexs[offset + 1] = pt.y - texture.getHeight() / 2f; //下移一段距离
vertexs[offset + 2] = pt.x / texture.getWidth();
vertexs[offset + 3] = 1;
vertexs[offset + 4] = pt.x;
vertexs[offset + 5] = pt.y + texture.getHeight() / 2f; //上移一段距离 其他的都一样
vertexs[offset + 6] = pt.x / texture.getWidth();
vertexs[offset + 7] = 0;
offset += 8;
}
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完整代码（groundActor）：
public class GroundActor extends Actor{
ShaderProgram shader;
Mesh mesh;
Array<Vector2> points;
private final Texture texture;
public GroundActor(Array<Vector2> points){
this.points = points;
texture = new Texture("tile.png");
texture.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear);
texture.setWrap(Texture.TextureWrap.Repeat, Texture.TextureWrap.Repeat);
float vertexs[] = new float[2 * 2 * 2 * points.size];
int offset = 0;
for (Vector2 point : points){
vertexs[offset + 0] = point.x;
vertexs[offset + 1] = 0;
vertexs[offset + 2] = point.x / texture.getWidth();
vertexs[offset + 3] = 0;
vertexs[offset + 4] = point.x;
vertexs[offset + 5] = point.y;
vertexs[offset + 6] = point.x / texture.getWidth();
vertexs[offset + 7] = point.y / texture.getHeight();
offset += 8;
}
shader = new ShaderProgram(Gdx.files.internal("surface_vertex.gles"), Gdx.files.internal
("surface_fragment.gles"));
mesh = new Mesh(true, points.size * 2, points.size * 2,
new VertexAttribute(VertexAttributes.Usage.Position, 2, "a_position"),
new VertexAttribute(VertexAttributes.Usage.TextureCoordinates, 2, "a_texCoord0"));
mesh.setVertices(vertexs);
short[] indices1 = new short[points.size * 2];
for (int i = 0; i < indices1.length; i++){
indices1[i] = (short) i;
}
mesh.setIndices(indices1);
}
@Override
public void draw(Batch batch, float parentAlpha) {
super.draw(batch, parentAlpha);
Gdx.gl.glEnable(GL20.GL_BLEND);
Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
shader.begin();
shader.setUniformMatrix("u_worldView", getStage().getCamera().combined);
texture.bind(0);
mesh.render(shader, GL20.GL_TRIANGLE_STRIP);
shader.end();
Gdx.gl.glDisable(GL20.GL_BLEND);
}
}
完整的代码（LineActor）
public class LineActor extends Actor{
ShaderProgram shader;
Mesh mesh;
Array<Vector2> points;
private Texture texture;
public LineActor(Array<Vector2> points){
this.points = points;
texture = new Texture("line.png");
texture.setFilter(Texture.TextureFilter.Linear, Texture.TextureFilter.Linear);
texture.setWrap(Texture.TextureWrap.Repeat, Texture.TextureWrap.Repeat);
float vertexs[] = new float[2 * 2 * 2 * points.size];
int offset = 0;
Vector2 pt = new Vector2();
for (int i = 0; i < points.size; ++i){
pt.set(points.get(i).cpy());
vertexs[offset + 0] = pt.x;
vertexs[offset + 1] = pt.y - texture.getHeight() / 2f;
vertexs[offset + 2] = pt.x / texture.getWidth();
vertexs[offset + 3] = 1;
vertexs[offset + 4] = pt.x;
vertexs[offset + 5] = pt.y + texture.getHeight() / 2f;
vertexs[offset + 6] = pt.x / texture.getWidth();
vertexs[offset + 7] = 0;
offset += 8;
}
shader = new ShaderProgram(Gdx.files.internal("surface_vertex.gles"), Gdx.files.internal
("surface_fragment.gles"));
mesh = new Mesh(true, points.size * 2, points.size * 2,
new VertexAttribute(VertexAttributes.Usage.Position, 2, ShaderProgram.POSITION_ATTRIBUTE),
new VertexAttribute(VertexAttributes.Usage.TextureCoordinates, 2, ShaderProgram
.TEXCOORD_ATTRIBUTE + "0"));
mesh.setVertices(vertexs);
short[] indices1 = new short[points.size * 2];
for (int i = 0; i < indices1.length; i++){
indices1[i] = (short) i;
}
mesh.setIndices(indices1);
}
@Override
public void draw(Batch batch, float parentAlpha) {
super.draw(batch, parentAlpha);
Gdx.gl.glEnable(GL20.GL_BLEND);
Gdx.gl.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);
texture.bind();
shader.begin();
shader.setUniformMatrix("u_worldView", getStage().getCamera().combined);
mesh.render(shader, GL20.GL_TRIANGLE_STRIP);
shader.end();
Gdx.gl.glDisable(GL20.GL_BLEND);
}
}
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