大概看过nehe的texture mapping代码之后,发现都是将一个纹理图片,按坐标映射的方式,来对应到点。
所以下面这段代码,对于了解这种映射方式的朋友来说,应该很好理解。
package com.kyugao.screen; import com.badlogic.gdx.Gdx; import com.badlogic.gdx.Screen; import com.badlogic.gdx.files.FileHandle; import com.badlogic.gdx.graphics.GL10; import com.badlogic.gdx.graphics.Mesh; import com.badlogic.gdx.graphics.PerspectiveCamera; import com.badlogic.gdx.graphics.Texture; import com.badlogic.gdx.graphics.VertexAttribute; import com.badlogic.gdx.graphics.VertexAttributes.Usage; public class TextureMapping implements Screen { private Mesh squareMesh; private PerspectiveCamera camera; private Texture texture; private float rquad = 0; @Override public void render(float delta) { camera.update(); camera.apply(Gdx.graphics.getGL10()); Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); Gdx.gl.glEnable(GL10.GL_DEPTH_TEST); Gdx.gl.glEnable(GL10.GL_TEXTURE_2D); drawGLScene(); rquad += 20f * delta; // 每秒钟转20度,计算在每一次render的时间差里,要转的角度。比如0.5秒,那就应该转10度。 rquad %= 360; } private boolean drawGLScene() { Gdx.gl10.glLoadIdentity(); Gdx.gl10.glTranslatef(0.0f, 0.0f, -7.0f); Gdx.gl10.glRotatef(rquad, 1.0f, 1.0f, 1.0f); Gdx.gl10.glTranslatef(0.0f, 0.0f, 7.0f); texture.bind(); for (int i = 0; i < squareMesh.getMaxVertices() / 4; i++) { squareMesh.render(GL10.GL_TRIANGLE_FAN, i * 4, 4); // 正方形的6个面分别画出. } return true; } @Override public void show() { squareMesh = new Mesh(true, 24, 24, new VertexAttribute(Usage.Position, 3, "b_position"), new VertexAttribute(Usage.TextureCoordinates, 2, "b_texture")); squareMesh.setVertices(new float[] { // Front face: -1f, 1.0f, -6.0f, 0f, 0f, // TL -1f, -1.0f, -6.0f, 0f, 1f, // BL 1f, -1.0f, -6.0f, 1f, 1f, // BR 1f, 1.0f, -6.0f, 1f, 0f, // TR // Top face: -1f, 1.0f, -8.0f, 0f, 0f, // LR -1f, 1.0f, -6.0f, 0f, 1f, // LN 1f, 1.0f, -6.0f, 1f, 1f, // RN 1f, 1.0f, -8.0f, 1f, 0f, // RR // Rear face 1f, 1.0f, -8.0f, 0f, 0f, // TR 1f, -1.0f, -8.0f, 0f, 1f, // BR -1f, -1.0f, -8.0f, 1f, 1f, // BL -1f, 1.0f, -8.0f, 1f, 0f, // TL // Bottom face -1f, -1.0f, -6.0f, 0f, 0f, // LN 1f, -1.0f, -6.0f, 0f, 1f,// RN 1f, -1.0f, -8.0f, 1f, 1f, // RR -1f, -1.0f, -8.0f, 1f, 0f, // LR // Left face -1f, 1.0f, -8.0f, 0f, 0f, // TR -1f, 1.0f, -6.0f, 0f, 1f, // TN -1f, -1.0f, -6.0f, 1f, 1f, // BN -1f, -1.0f, -8.0f, 1f, 0f, // BR // Right face 1f, 1.0f, -6.0f, 0f, 0f, // TN 1f, 1.0f, -8.0f, 1f, 0f, // TR 1f, -1.0f, -8.0f, 1f, 1f, // BR 1f, -1.0f, -6.0f, 0f, 1f // BN }); squareMesh.setIndices(new short[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 }); FileHandle imageFileHandle = Gdx.files.internal("data/NeHe.bmp"); texture = new Texture(imageFileHandle); } @Override public void hide() { } @Override public void pause() { } @Override public void resume() { } @Override public void dispose() { } @Override public void resize(int width, int height) { float aspectRatio = (float) width / (float) height; camera = new PerspectiveCamera(45, 2f * aspectRatio, 2f); } }
有一个gl的参数需要设置,这个是使用texture时需要的。
Gdx.gl.glEnable(GL10.GL_TEXTURE_2D);
再大概说一下纹理的映射:// Front face:
-1f, 1.0f, -6.0f, 0f, 0f,// TL
-1f, -1.0f, -6.0f, 0f, 1f,// BL
1f, -1.0f, -6.0f, 1f, 1f,// BR
1f, 1.0f, -6.0f, 1f, 0f,// TR
以上坐标描述的是正方体前面(面对我们这一面)每一行前三个数表示一个点的坐标,如:x=-1, y=1, z=-6.0.
接下来两个数表示的是这一点,对应纹理图片上的哪一点。
纹理图片,我们也用一个坐标来表示,那左上角为(0,0),右上角为(1,0),右下角为(1,1),左下角为(0,1)
所以,对应到正方形上就是,点TL(0,0)点BL(0,1)点BR(1,1)点TR(1,0)
于是,我们程序的效果就是: