1 前言

紋理貼圖的本質(zhì)是將圖片的紋理坐標與模型的頂點坐標建立一一映射關(guān)系跷叉。紋理坐標的 x好乐、y 軸正方向分別朝右和朝下肌毅，如下。

2 紋理貼圖

本節(jié)將使用 Mesh筐喳、ShaderProgram催式、Shader 實現(xiàn)紋理貼圖函喉，OpenGL ES 的實現(xiàn)見博客 → 紋理貼圖，本節(jié)完整代碼資源見 → libGDX Mesh紋理貼圖荣月。

DesktopLauncher.java

package com.zhyan8.game;

import com.badlogic.gdx.backends.lwjgl3.Lwjgl3Application;
import com.badlogic.gdx.backends.lwjgl3.Lwjgl3ApplicationConfiguration;
import com.zhyan8.game.Chartlet;

public class DesktopLauncher {
    public static void main (String[] arg) {
        Lwjgl3ApplicationConfiguration config = new Lwjgl3ApplicationConfiguration();
        config.setForegroundFPS(60);
        config.setTitle("Chartlet");
        new Lwjgl3Application(new Chartlet(), config);
    }
}

Chartlet.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.Texture;
import com.badlogic.gdx.graphics.VertexAttribute;
import com.badlogic.gdx.graphics.VertexAttributes.Usage;
import com.badlogic.gdx.graphics.glutils.ShaderProgram;

public class Chartlet extends ApplicationAdapter {
    private ShaderProgram mShaderProgram;
    private Mesh mMesh;
    private Texture mTexture;

    @Override
    public void create() {
        initShader();
        initMesh();
        mTexture = new Texture(Gdx.files.internal("textures/girl.jpg"));
    }

    @Override
    public void render() {
        Gdx.gl.glClearColor(0.455f, 0.725f, 1.0f, 1.0f);
        Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT);
        mShaderProgram.bind();
        // mShaderProgram.setUniformi("u_texture", 0); // 設(shè)置紋理單元
        mTexture.bind(0);
        mMesh.render(mShaderProgram, GL30.GL_TRIANGLE_FAN);
    }

    @Override
    public void dispose() {
        mShaderProgram.dispose();
        mMesh.dispose();
    }

    private void initShader() { // 初始化著色器程序
        String vertex = Gdx.files.internal("shaders/chartlet_vertex.glsl").readString();
        String fragment = Gdx.files.internal("shaders/chartlet_fragment.glsl").readString();
        mShaderProgram = new ShaderProgram(vertex, fragment);
    }

    private void initMesh() { // 初始化網(wǎng)格
        float[] vertices = {
                -1f, -1f, 0f, 0f, 1f, // 左下
                1f, -1f, 0f, 1f, 1f, // 右下
                1f, 1f, 0f, 1f, 0f, // 右上
                -1f, 1f, 0f, 0f, 0f // 左上
        };
        short[] indices = {0, 1, 2, 3};
        VertexAttribute vertexPosition = new VertexAttribute(Usage.Position, 3, "a_position");
        VertexAttribute texCoords = new VertexAttribute(Usage.TextureCoordinates, 2, "a_texCoord0");
        mMesh = new Mesh(true, vertices.length / 5, indices.length, vertexPosition, texCoords);
        mMesh.setVertices(vertices);
        mMesh.setIndices(indices);
    }
}

chartlet_vertex.glsl

#version 300 es

in vec3 a_position;
in vec2 a_texCoord0;

out vec2 v_texCoord0;

void main() {
    gl_Position = vec4(a_position, 1.0);
    v_texCoord0 = a_texCoord0;
}

chartlet_fragment.glsl

#version 300 es
precision mediump float; // 聲明float型變量的精度為mediump

in vec2 v_texCoord0;

uniform sampler2D u_texture;

out vec4 fragColor;

void main() {
    fragColor = texture(u_texture, v_texCoord0);
}

運行效果管呵。

聲明：本文轉(zhuǎn)自【libGDX】Mesh紋理貼圖。