济南网站搜索优化,网络程序开发,aspx 网站开发工具,设计好看的网站1 前言 使用Mesh绘制三角形 中介绍了绘制三角形的方法#xff0c;使用Mesh绘制矩形 中介绍了绘制矩形的方法#xff0c;本文将介绍绘制圆形的方法。 libGDX 以点、线段、三角形为图元#xff0c;没有提供绘制圆形的接口。要绘制圆形边框#xff0c;必须通过割圆法逼近圆形使用Mesh绘制矩形 中介绍了绘制矩形的方法本文将介绍绘制圆形的方法。 libGDX 以点、线段、三角形为图元没有提供绘制圆形的接口。要绘制圆形边框必须通过割圆法逼近圆形要绘制圆形的内部必须通过三角形逼近圆形如下图是通过 GL_TRIANGLE_FAN 模式逼近圆形。 2 绘制圆形 DesktopLauncher.java
package com.zhyan8.game;import com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application;
import com.badlogic.gdx.backends.lwjgl3.Lwjgl3ApplicationConfiguration;public class DesktopLauncher {public static void main (String[] arg) {Lwjgl3ApplicationConfiguration config new Lwjgl3ApplicationConfiguration();config.setForegroundFPS(60);config.setTitle(Circle);new Lwjgl3Application(new Circle(), config);}
} Circle.java
package com.zhyan8.game;import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.GL30;
import com.badlogic.gdx.graphics.Mesh;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;public class Circle extends ApplicationAdapter {private ShaderProgram mShaderProgram;private Mesh mMesh;private float mRatio;Overridepublic void create() {initShader();initMesh();}Overridepublic void render() {Gdx.gl.glClearColor(0.455f, 0.725f, 1.0f, 1.0f);Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT);mShaderProgram.bind();mShaderProgram.setUniformf(u_wh_ratio, mRatio);mMesh.render(mShaderProgram, GL30.GL_TRIANGLE_FAN); // 绘制圆形内部// mMesh.render(mShaderProgram, GL30.GL_LINE_LOOP); // 绘制圆形框}Overridepublic void dispose() {mShaderProgram.dispose();mMesh.dispose();}private void initShader() { // 初始化着色器程序String vertex Gdx.files.internal(shaders/circle_vertex.glsl).readString();String fragment Gdx.files.internal(shaders/circle_fragment.glsl).readString();mShaderProgram new ShaderProgram(vertex, fragment);mRatio 1.0f * Gdx.graphics.getWidth() / Gdx.graphics.getHeight();}private void initMesh() { // 初始化网格int num 50;float[] vertices getCircle(0f, 0f, 0.5f, num);short[] indices getIndices(num);VertexAttribute vertexPosition new VertexAttribute(Usage.Position, 3, a_position);mMesh new Mesh(true, vertices.length / 3, indices.length, vertexPosition);mMesh.setVertices(vertices);mMesh.setIndices(indices);}private float[] getCircle(float centerX, float centerY, float radius, int num) {float unit (float)(2 * Math.PI / num);float[] coords new float[num * 3];for (int i 0; i num; i) {coords[i * 3] (float)(centerX radius * Math.cos(unit * i));coords[i * 3 1] (float)(centerY radius * Math.sin(unit * i));coords[i * 3 2] 0;}return coords;}private short[] getIndices(int num) {short[] indices new short[num];for (short i 0; i num; i) {indices[i] i;}return indices;}
} circle_vertex.glsl
#version 300 esin vec3 a_position;uniform float u_wh_ratio; // 屏幕宽高比void main() {gl_Position vec4(a_position, 1.0);if (u_wh_ratio 1.0) {gl_Position.x / u_wh_ratio;} else {gl_Position.y * u_wh_ratio;}
} circle_fragment.glsl
#version 300 es
precision mediump float; // 声明float型变量的精度为mediumpout vec4 fragColor;void main() {fragColor vec4(1, 0, 0, 0);
}
