Opengl ES系列学习--光照基础
本节我们来学习一下光照基础的知识，理解了原作者的讲解，我们就应该能提炼出本节的重点就是冯氏光照模型。之前我们已经说过了，后面的效果实现都是把前人总结好的原理计算出来。冯氏光照模型介绍如下：
上面的四张效果图看着就非常明显了，第一张是环境光，第二张是漫反射，第三张是镜面反射，第四张是所有效果的综合，也就是我们眼睛看到的效果。颜色的处理是在片段着色器中，分别把三部分反射因子相加，然后乘以物体本身的颜色就完成了，代码实现如下：
本节我们最终实现的效果图如下：
我们画了四个立方体，中间这个就是冯氏光照模式的最终效果，中间正上方的是单独镜面反射的效果，中间右上的环境光 + 漫反射的效果，左下角的是单独环境光的效果。我们把光源的颜色设置为白色，可以看到最终的效果才更接近实际情况，不会像单独环境光或者漫反射那样整体是一个颜色。
我们再加上纹理看一下效果：
有了纹理采样，细节更加突出，有点小兴奋。不过大家看看B站上那些Opengl作出来的游戏效果，就会发现，我们现在作的所有都是小菜，真的太菜了，但是也不要紧，当前的基础积累就是以后万丈高楼的根基。
本节的效果有三个类：GlLightRender、LightCube、LightLight，GlLightRender类和上一节基本完全相同，还是提供绘制的流程；LightCube绘制立方体；LightLight绘制光源。我们先来看一下LightLight类，完整源码如下：
package com.opengl.learn.aric.light;
import android.content.Context;
import android.opengl.GLES32;
import android.opengl.Matrix;
import com.opengl.learn.OpenGLUtils;
import com.opengl.learn.R;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.opengles.GL10;
import static android.opengl.GLES20.GL_ARRAY_BUFFER;
import static android.opengl.GLES20.GL_FLOAT;
import static android.opengl.GLES20.GL_STATIC_DRAW;
import static android.opengl.GLES20.GL_TRIANGLES;
import static android.opengl.GLES20.glGenBuffers;
import static android.opengl.GLES20.glGetUniformLocation;
public class LightLight {
private final float[] mVerticesData =
{
// back face
0.5f, 0.5f, -0.5f, // (5) Top-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, 0.5f, -0.5f, // (4) Top-left far
0.5f, 0.5f, -0.5f, // (5) Top-right far
// front face
-0.5f, 0.5f, 0.5f, // (0) Top-left near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, 0.5f, 0.5f, // (1) Top-right near
-0.5f, 0.5f, 0.5f, // (0) Top-left near
// left face
-0.5f, 0.5f, -0.5f, // (4) Top-left far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, 0.5f, 0.5f, // (0) Top-left near
-0.5f, 0.5f, -0.5f, // (4) Top-left far
// right face
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, 0.5f, -0.5f, // (5) Top-right far
0.5f, 0.5f, 0.5f, // (1) Top-right near
// bottom face
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
// top face
-0.5f, 0.5f, -0.5f, // (4) Top-left far
-0.5f, 0.5f, 0.5f, // (0) Top-left near
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, 0.5f, -0.5f, // (5) Top-right far
-0.5f, 0.5f, -0.5f, // (4) Top-left far
};
public static final float[] mLightColorsData = {1.0f, 1.0f, 1.0f};
public static final float[] mLightPosData = {0f, 0f, 5.0f};
private static final String TAG = LightLight.class.getSimpleName();
private static final int BYTES_PER_FLOAT = 4;
private static final int BYTES_PER_SHORT = 2;
private static final int POSITION_COMPONENT_COUNT = 3;
private static final int COLOR_COMPONENT_COUNT = 3;
private static final int TEXTURE_COMPONENT_COUNT = 2;
private static final int INDEX_COMPONENT_COUNT = 1;
private static final int MATRIX_LENGHT = 16;
private Context mContext;
private int mLightProgram;
private int uLightMatrixLocation, uLightColor;
private FloatBuffer mVerticesBuffer;
private FloatBuffer mColorsBuffer;
private int mWidth, mHeight;
private int mLightVAO, mLightVBO;
private float[] uLightMatrix = new float[MATRIX_LENGHT];
private float[] projectionMatrix = new float[MATRIX_LENGHT];
private float[] modelMatrix = new float[MATRIX_LENGHT];
private float[] viewMatrix = new float[MATRIX_LENGHT];
public LightLight(Context context) {
mContext = context;
mVerticesBuffer = ByteBuffer.allocateDirect(mVerticesData.length * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mVerticesBuffer.put(mVerticesData).position(0);
}
public void onSurfaceCreated() {
mLightProgram = OpenGLUtils.loadProgram(mContext, R.raw.gllight_light_vertex, R.raw.gllight_light_fragment);
uLightMatrixLocation = glGetUniformLocation(mLightProgram, "uMatrix");
uLightColor = glGetUniformLocation(mLightProgram, "uLightColor");
int[] array = new int[1];
GLES32.glGenVertexArrays(1, array, 0);
mLightVAO = array[0];
array = new int[1];
glGenBuffers(1, array, 0);
mLightVBO = array[0];
GLES32.glBindVertexArray(mLightVAO);
mVerticesBuffer.position(0);
GLES32.glBindBuffer(GL_ARRAY_BUFFER, mLightVBO);
GLES32.glBufferData(GL_ARRAY_BUFFER, BYTES_PER_FLOAT * mVerticesData.length, mVerticesBuffer, GL_STATIC_DRAW);
GLES32.glVertexAttribPointer(0, POSITION_COMPONENT_COUNT, GL_FLOAT, false, 0, 0);
GLES32.glEnableVertexAttribArray(0);
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
mWidth = width;
mHeight = height;
}
public void onDrawFrame() {
GLES32.glUseProgram(mLightProgram);
GLES32.glEnableVertexAttribArray(0);
GLES32.glBindVertexArray(mLightVAO);
setLightMatrix();
GLES32.glUniformMatrix4fv(uLightMatrixLocation, 1, false, uLightMatrix, 0);
GLES32.glUniform3fv(uLightColor, 1, mLightColorsData, 0);
GLES32.glDrawArrays(GL_TRIANGLES, 0, mVerticesData.length);
GLES32.glBindVertexArray(0);
GLES32.glDisableVertexAttribArray(3);
}
private void setLightMatrix() {
Matrix.setIdentityM(modelMatrix, 0);
Matrix.setIdentityM(viewMatrix, 0);
float aspect = (float) mWidth / (float) mHeight;
Matrix.perspectiveM(projectionMatrix, 0, 45f, aspect, 1.0f, 100f);
Matrix.setLookAtM(viewMatrix, 0, 0f, 10f, 20f, 0f, 0f, 0f, 0f, 1f, 0f);
Matrix.translateM(modelMatrix, 0, mLightPosData[0], mLightPosData[1], mLightPosData[2]);
Matrix.scaleM(modelMatrix, 0, 0.5f, 0.5f, 0.5f);
Matrix.rotateM(modelMatrix, 0, -60, 0f, 1f, 0f);
Matrix.multiplyMM(uLightMatrix, 0, viewMatrix, 0, modelMatrix, 0);
Matrix.multiplyMM(uLightMatrix, 0, projectionMatrix, 0, uLightMatrix, 0);
}
}因为在绘制立方体的时候，也要使用到光源的一些属性，所以我们把光源颜色mLightColorsData、光源位置mLightPosData都修饰为public static属性，在立方体的绘制中方便使用，光源颜色设置为白色，光源的透视投影矩阵、视图矩阵和绘制立方体的完全相同，我们把光源沿X、Y、Z三个轴都缩小一半，其他的就没有什么特殊的地方了。
光源的顶点着色器源码如下：
#version 320 es
layout(location = 0) in vec3 aPosition;
uniform mat4 uMatrix;
void main()
{
gl_Position = uMatrix * vec4(aPosition, 1.0);
}很简单，就是用计算完的矩阵和顶点位置相乘得到最终的顶点位置。片段着色器的源码如下：
#version 320 es
precision mediump float;
uniform vec3 uLightColor;
out vec4 FragColor;
void main()
{
FragColor = vec4(uLightColor, 1f);
}片段着色器使用我们定义的mLightColorsData白色直接绘制。
再来看一下LightCube，完整源码如下：
package com.opengl.learn.aric.light;
import android.content.Context;
import android.opengl.GLES32;
import android.opengl.Matrix;
import android.util.Log;
import com.opengl.learn.OpenGLUtils;
import com.opengl.learn.R;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import javax.microedition.khronos.opengles.GL10;
import static android.opengl.GLES20.GL_ARRAY_BUFFER;
import static android.opengl.GLES20.GL_FLOAT;
import static android.opengl.GLES20.GL_STATIC_DRAW;
import static android.opengl.GLES20.GL_TEXTURE0;
import static android.opengl.GLES20.GL_TEXTURE1;
import static android.opengl.GLES20.GL_TEXTURE_2D;
import static android.opengl.GLES20.GL_TRIANGLES;
import static android.opengl.GLES20.glGenBuffers;
import static android.opengl.GLES20.glGetUniformLocation;
public class LightCube {
private final float[] mVerticesData =
{
// back face
0.5f, 0.5f, -0.5f, // (5) Top-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, 0.5f, -0.5f, // (4) Top-left far
0.5f, 0.5f, -0.5f, // (5) Top-right far
// front face
-0.5f, 0.5f, 0.5f, // (0) Top-left near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, 0.5f, 0.5f, // (1) Top-right near
-0.5f, 0.5f, 0.5f, // (0) Top-left near
// left face
-0.5f, 0.5f, -0.5f, // (4) Top-left far
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, 0.5f, 0.5f, // (0) Top-left near
-0.5f, 0.5f, -0.5f, // (4) Top-left far
// right face
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, 0.5f, -0.5f, // (5) Top-right far
0.5f, 0.5f, 0.5f, // (1) Top-right near
// bottom face
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
-0.5f, -0.5f, -0.5f, // (6) Bottom-left far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, -0.5f, // (7) Bottom-right far
0.5f, -0.5f, 0.5f, // (3) Bottom-right near
-0.5f, -0.5f, 0.5f, // (2) Bottom-left near
// top face
-0.5f, 0.5f, -0.5f, // (4) Top-left far
-0.5f, 0.5f, 0.5f, // (0) Top-left near
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, 0.5f, 0.5f, // (1) Top-right near
0.5f, 0.5f, -0.5f, // (5) Top-right far
-0.5f, 0.5f, -0.5f, // (4) Top-left far
};
private final float[] mColorsData =
{
1.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 1.0f,
1.0f, 1.0f, 0.0f,
};
private final float[] mTextureData =
{
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
0.0f, 0.0f,
0.0f, 1.0f,
1.0f, 1.0f,
1.0f, 1.0f,
1.0f, 0.0f,
0.0f, 0.0f,
};
private final float[] mNormalData =
{
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, -1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
-1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
1.0f, 0.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, -1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
0.0f, 1.0f, 0.0f,
};
private final float[] mEyePosData = {0f, 2f, 20f};
private static final String TAG = LightCube.class.getSimpleName();
private static final int BYTES_PER_FLOAT = 4;
private static final int BYTES_PER_SHORT = 2;
private static final int POSITION_COMPONENT_COUNT = 3;
private static final int COLOR_COMPONENT_COUNT = 3;
private static final int TEXTURE_COMPONENT_COUNT = 2;
private static final int INDEX_COMPONENT_COUNT = 1;
private static final int NORMAL_COMPONENT_COUNT = 3;
private static final int MATRIX_LENGHT = 16;
private Context mContext;
private int mProgramObject;
private int uTextureContainer, containerTexture;
private int uTextureFace, faceTexture;
private int uModelMatrix, uViewMatrix, uProjectionMatrix, uLightColor, uLightPos, uViewPos, uIndex;
private FloatBuffer mVerticesBuffer;
private FloatBuffer mColorsBuffer;
private FloatBuffer mTextureBuffer;
private FloatBuffer mNormalBuffer;
private ShortBuffer mIndicesBuffer;
private int mWidth, mHeight;
private int mVAO, mVBO, mCBO, mTBO, mNBO;
private float[] modelMatrix = new float[MATRIX_LENGHT];
private float[] viewMatrix = new float[MATRIX_LENGHT];
private float[] projectionMatrix = new float[MATRIX_LENGHT];
private float radius = 30f;
private long startTime = 0;
private float[][] directions = {
{0f, 0.0f, -10f}, {4.3f, 4.7f, -15.0f}, {-4.5f, -10.2f, -20.5f}, {0f, 4.2f, -20.5f}, {3.24f, -3.4f, -15.5f},
{-3.1f, 2.0f, -7.5f}, {4.47f, -2.0f, -5.5f}, {-4.5f, 2.40f, -9.5f}, {5f, 0.2f, -20.5f}, {-5.43f, -2.3f, -8.5f},
};
public LightCube(Context context) {
mContext = context;
mVerticesBuffer = ByteBuffer.allocateDirect(mVerticesData.length * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mVerticesBuffer.put(mVerticesData).position(0);
mColorsBuffer = ByteBuffer.allocateDirect(mColorsData.length * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mColorsBuffer.put(mColorsData).position(0);
mTextureBuffer = ByteBuffer.allocateDirect(mTextureData.length * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mTextureBuffer.put(mTextureData).position(0);
mNormalBuffer = ByteBuffer.allocateDirect(mNormalData.length * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mNormalBuffer.put(mNormalData).position(0);
}
public void onSurfaceCreated() {
mProgramObject = OpenGLUtils.loadProgram(mContext, R.raw.gllight_cube_vertex, R.raw.gllight_cube_fragment);
uTextureContainer = glGetUniformLocation(mProgramObject, "uTextureContainer");
uTextureFace = glGetUniformLocation(mProgramObject, "uTextureFace");
uModelMatrix = glGetUniformLocation(mProgramObject, "uModelMatrix");
uViewMatrix = glGetUniformLocation(mProgramObject, "uViewMatrix");
uProjectionMatrix = glGetUniformLocation(mProgramObject, "uProjectionMatrix");
uLightColor = glGetUniformLocation(mProgramObject, "uLightColor");
uLightPos = glGetUniformLocation(mProgramObject, "uLightPos");
uViewPos = glGetUniformLocation(mProgramObject, "uViewPos");
uIndex = glGetUniformLocation(mProgramObject, "uIndex");
int[] array = new int[1];
GLES32.glGenVertexArrays(1, array, 0);
mVAO = array[0];
array = new int[4];
glGenBuffers(4, array, 0);
mVBO = array[0];
mCBO = array[1];
mTBO = array[2];
mNBO = array[3];
Log.e(TAG, "onSurfaceCreated, " + mProgramObject + ", uTexture: " + uTextureContainer + ", uTextureFace: " + uTextureFace);
containerTexture = OpenGLUtils.loadTexture(mContext, R.mipmap.container);
faceTexture = OpenGLUtils.loadTexture(mContext, R.mipmap.awesomeface);
GLES32.glBindVertexArray(mVAO);
mVerticesBuffer.position(0);
GLES32.glBindBuffer(GL_ARRAY_BUFFER, mVBO);
GLES32.glBufferData(GL_ARRAY_BUFFER, BYTES_PER_FLOAT * mVerticesData.length, mVerticesBuffer, GL_STATIC_DRAW);
GLES32.glVertexAttribPointer(0, POSITION_COMPONENT_COUNT, GL_FLOAT, false, 0, 0);
GLES32.glEnableVertexAttribArray(0);
mTextureBuffer.position(0);
GLES32.glBindBuffer(GL_ARRAY_BUFFER, mTBO);
GLES32.glBufferData(GL_ARRAY_BUFFER, BYTES_PER_FLOAT * mTextureData.length, mTextureBuffer, GL_STATIC_DRAW);
GLES32.glVertexAttribPointer(2, TEXTURE_COMPONENT_COUNT, GL_FLOAT, false, 0, 0);
GLES32.glEnableVertexAttribArray(2);
mNormalBuffer.position(0);
GLES32.glBindBuffer(GL_ARRAY_BUFFER, mNBO);
GLES32.glBufferData(GL_ARRAY_BUFFER, BYTES_PER_FLOAT * mNormalData.length, mNormalBuffer, GL_STATIC_DRAW);
GLES32.glVertexAttribPointer(3, NORMAL_COMPONENT_COUNT, GL_FLOAT, false, 0, 0);
GLES32.glEnableVertexAttribArray(3);
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
mWidth = width;
mHeight = height;
}
public void onDrawFrame() {
if (startTime == 0) {
startTime = System.currentTimeMillis();
}
GLES32.glUseProgram(mProgramObject);
GLES32.glEnableVertexAttribArray(0);
GLES32.glEnableVertexAttribArray(1);
GLES32.glEnableVertexAttribArray(2);
GLES32.glEnableVertexAttribArray(3);
GLES32.glActiveTexture(GL_TEXTURE0);
GLES32.glBindTexture(GL_TEXTURE_2D, containerTexture);
GLES32.glUniform1i(uTextureContainer, 0);
GLES32.glActiveTexture(GL_TEXTURE1);
GLES32.glBindTexture(GL_TEXTURE_2D, faceTexture);
GLES32.glUniform1i(uTextureFace, 1);
GLES32.glUniform3fv(uLightColor, 1, LightLight.mLightColorsData, 0);
GLES32.glUniform3fv(uLightPos, 1, LightLight.mLightPosData, 0);
GLES32.glUniform3fv(uViewPos, 1, mEyePosData, 0);
GLES32.glBindVertexArray(mVAO);
for (int i = 0; i < 4; i++) {
setCubeMatrix(i);
GLES32.glUniformMatrix4fv(uModelMatrix, 1, false, modelMatrix, 0);
GLES32.glUniformMatrix4fv(uViewMatrix, 1, false, viewMatrix, 0);
GLES32.glUniformMatrix4fv(uProjectionMatrix, 1, false, projectionMatrix, 0);
GLES32.glUniform1i(uIndex, i);
GLES32.glDrawArrays(GL_TRIANGLES, 0, mVerticesData.length);
}
GLES32.glBindVertexArray(0);
GLES32.glDisableVertexAttribArray(0);
GLES32.glDisableVertexAttribArray(1);
GLES32.glDisableVertexAttribArray(2);
GLES32.glDisableVertexAttribArray(3);
}
private void setCubeMatrix(int i) {
Matrix.setIdentityM(modelMatrix, 0);
Matrix.setIdentityM(viewMatrix, 0);
Matrix.setIdentityM(projectionMatrix, 0);
float aspect = (float) mWidth / (float) mHeight;
Matrix.perspectiveM(projectionMatrix, 0, 45f, aspect, 1.0f, 100f);
long now = System.currentTimeMillis();
float camX = (float) (Math.sin((now - startTime) / 1000f) * radius);
float camZ = (float) (Math.cos((now - startTime) / 1000f) * radius);
Matrix.setLookAtM(viewMatrix, 0, mEyePosData[0], mEyePosData[1], mEyePosData[2], 0f, 0f, 0f, 0f, 1f, 0f);
Matrix.translateM(modelMatrix, 0, directions[i][0], directions[i][1], directions[i][2]);
float scale = i == 0 ? 4.5f : 3f;
Matrix.scaleM(modelMatrix, 0, scale, scale, scale);
}
}在onDrawFrame方法中，我们执行glDrawArrays四次，画出上图中的四个立方体，画立方体时传入的uLightColor、uLightPos都是前面我们在LightLight类中定义的公有成员变量；另外我们为了在片段着色器中区分出四个立方体，单独定义了一个uniform int uIndex变量，等下我们在片段着色器中就可以看到。该类中也没有其他需要重点说明的东西了。
接着看一下立方体的顶点着色器，完整源码如下：
#version 320 es
layout(location = 0) in vec3 aPosition;
layout(location = 1) in vec3 aColor;
layout(location = 2) in vec2 aTexCoord;
layout(location = 3) in vec3 aNormal;
uniform mat4 uModelMatrix;
uniform mat4 uViewMatrix;
uniform mat4 uProjectionMatrix;
out vec3 outColor;
out vec2 outTexCoord;
out vec3 outNormal;
out vec3 outFragPos;
void main()
{
outColor = aColor;
outTexCoord = aTexCoord;
outNormal = aNormal;
outFragPos = vec3(uModelMatrix * vec4(aPosition, 1.0f));
gl_Position = uProjectionMatrix * uViewMatrix * uModelMatrix * vec4(aPosition, 1.0);
}和上一节不同，因为我们要单独使用modelMatrix，这样就不能在CPU中计算完，把结果矩阵传进来，所以我们把modelMatrix、viewMatrix、projectionMatrix全部传进来，在GPU中进行计算，还是记住顺序从右往左！！另外我们在顶点属性中新增了法线aNormal，法线变量需要传入到片段着色器计算使用；还计算出片段坐标outFragPos，也是要传递到片段着色器计算使用。
再来看一下立方体的片段着色器，源码如下：
#version 320 es
precision mediump float;
out vec4 FragColor;
in vec3 outColor;
in vec2 outTexCoord;
in vec3 outNormal;
in vec3 outFragPos;
uniform sampler2D uTextureContainer;
uniform sampler2D uTextureFace;
uniform vec3 uLightColor;
uniform vec3 uLightPos;
uniform vec3 uViewPos;
uniform int uIndex;
vec4 getAmbientFactor() {
float ambientStrength = 0.2f;
vec4 ambient = vec4(ambientStrength * uLightColor, 1.0f);
return ambient;
}
vec4 getDiffuseFactor() {
vec3 normal = normalize(outNormal);
vec3 lightDir = normalize(uLightPos - outFragPos);
float diff = max(dot(normal, lightDir), 0.0);
vec3 diffuse = diff * uLightColor;
return vec4(diffuse, 1.0f);
}
vec4 getSpecularFactor() {
float specularStrength = 0.5f;
vec3 viewDir = normalize(uViewPos - outFragPos);
vec3 lightDir = normalize(uLightPos - outFragPos);
vec3 reflectDir = reflect(-lightDir, outNormal);
float spec = pow(max(dot(viewDir, reflectDir), 0.0f), 32.0f);
vec3 specular = specularStrength * spec * uLightColor;
return vec4(specular, 1.0f);
}
void main() {
vec4 objectColor = mix(texture(uTextureContainer, outTexCoord), texture(uTextureFace, outTexCoord), 0.2);
// objectColor = vec4(1.0f, 0.5f, 0.31f, 1.0f);
vec4 ambient = getAmbientFactor();
vec4 diffuse = getDiffuseFactor();
vec4 specular = getSpecularFactor();
if (uIndex == 0) {
FragColor = (ambient + diffuse + specular) * objectColor;
} else if (uIndex == 1) {
FragColor = (ambient + diffuse) * objectColor;
} else if (uIndex == 2) {
FragColor = (ambient) * objectColor;
} else if (uIndex == 3) {
FragColor = (specular) * objectColor;
}
}片段着色器也是Opengl产生各种炫丽效果的地方，可以看看，我们的片段着色器中的逻辑也越来越复杂了。第一个点需要说明就是pow函数，最后的参数不能传32，这样在着色器编译时，会调用pow带有int类型参数的函数，但是根本没有这样的函数定义，所以会导致编译报错，正确的应该使用32.0f！
所有自定义的函数需要写在main函数的上面，否则也会因为引用不到导致编译报错。getAmbientFactor函数是计算环境光照因子的，这里的float ambientStrength = 0.2f取值没有任何参考，只是我们的一个估值而已，用它乘以光照颜色就可以得到环境光照因子了；getDiffuseFactor函数是计算漫反射因子的，具体的计算过程大家可以参看原作者的讲解，已经非常清楚了，以后的实现也可以抛开原理，直接把对应的值传进来，按照顺序进行计算就可以了；getSpecularFactor函数是计算镜面光反射因子的，该函数的每一步也就是原原本本的计算思路了，只需要把对应的变量得到传进来就可以了；最后把三个因子相加，再乘以物体颜色就得到最终结果了（FragColor = (ambient + diffuse + specular) * objectColor）。
好，本节的内容到这里就结束了，下一节我们继续学习材质内容。