GLES学习笔记---立方体贴图（一张图）

本文主要是介绍GLES学习笔记---立方体贴图（一张图），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

一、首先看一张效果图

二、纹理坐标划分

如上图是一张2D纹理，我们需要将这个2D纹理贴到立方体上，立方体有6个面，所以上面的2D图分成了6个面，共有14个纹理坐标

三、立方体

上边的立方体一共8个顶点坐标，范围是[-1, 1]；

我们要做的是将纹理图贴到这6个面上面

四、顶点坐标纹理坐标关联

我们绘制的时候使用了VBO、VAO、EBO、

vertices里面是纹理坐标和顶点坐标的对应关系，纹理贴到哪个顶点上面；纹理坐标一共十四个，贴到8个顶点上。

indices里面是绘制的12个三角形

float DP = 0.5f;/*顶点               纹理*/float vertices[] = {-DP, -DP, DP,     0.25,  0.333,  //0DP, -DP, DP,     0.50,  0.333,  //1DP,  DP, DP,     0.50,  0.666,  //2-DP,  DP, DP,     0.25,  0.666,  //3-DP, -DP, -DP,    1.00,  0.333,  //4DP, -DP, -DP,    0.75,  0.333,  //5DP,  DP, -DP,    0.75,  0.666,  //6-DP,  DP, -DP,    1.00,  0.666,  //7-DP, -DP, -DP,    0.25,    0,    //4  8DP, -DP, -DP,      0.5,    0,    //5  9DP,  DP, -DP,      0.5,    1,    //6  10-DP,  DP, -DP,    0.25,    1,    //7  11-DP, -DP, -DP,       0,  0.333,  //4  12-DP,  DP, -DP,       0,  0.666,  //7  13};unsigned int indices[] = {0, 1, 2, 0, 2, 3,  // front1, 2, 5, 2, 5, 6,  // right4, 5, 6, 4, 6, 7,  // back0, 3, 12, 3, 12, 13, // left0, 1, 8, 1, 8, 9,  // bottom2, 3, 10, 3, 10, 11, // top};

五、完整代码

有部分代码是测试用的，不用细究奇怪的逻辑

//
// Created by fengcheng.cai on 2023/12/15.
//
#define EGL_EGLEXT_PROTOTYPES
#define GL_GLEXT_PROTOTYPES#include "com_sprd_opengl_test_MyNdk4.h"
#include <ggl.h>
#include <string.h>
#include <unistd.h>
#include <android/bitmap.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>#define LOG_TAG "MyNdk4"struct GL_Context4 {GLint program;EGLDisplay display;EGLSurface winSurface;EGLContext context;ANativeWindow *nw;AImageReader *reader;
};
static GL_Context4 gl_cxt;static char *vertexSimpleShape = "#version 300 es\n""layout (location = 0) in vec4 aPosition;\n""layout (location = 1) in vec2 aTexCoord;\n""uniform mat4 u_MVPMatrix;\n""out vec2 TexCoord;\n""void main() {\n""     gl_Position = u_MVPMatrix * aPosition;\n""     TexCoord = aTexCoord;\n""}\n";static char *fragSimpleShape = "#version 300 es\n""  precision  mediump float;\n""  in vec2 TexCoord;\n""  out vec4 FragColor;\n""  uniform sampler2D ourTexture;\n""  void main() {\n""       FragColor = texture(ourTexture, TexCoord);\n""  }\n";static GLint initShader(const char *source, GLint type) {//创建着色器对象，type表示着色器类型，比如顶点着色器为GL_VERTEX_SHADER，片段着色器为GL_FRAGMENT_SHADER。返回值为一个类似引用的数字。GLint sh = glCreateShader(type);if (sh == 0) {//返回值sh为0则表示创建着色器失败LOGD("glCreateShader %d failed", type);return 0;}//着色器对象加载着色器对象代码sourceglShaderSource(sh,1,//shader数量&source,0);//代码长度，传0则读到字符串结尾//编译着色器对象glCompileShader(sh);//以下为打印出编译异常信息GLint status;glGetShaderiv(sh, GL_COMPILE_STATUS, &status);if (status == 0) {LOGD("glCompileShader %d failed", type);LOGD("source %s", source);auto *infoLog = new GLchar[512];GLsizei length;glGetShaderInfoLog(sh, 512, &length, infoLog);LOGD("ERROR::SHADER::VERTEX::COMPILATION_FAILED %s", infoLog);return 0;}LOGD("glCompileShader %d success", type);return sh;
}JNIEXPORT void JNICALL Java_com_sprd_opengl_test_MyNdk4_init(JNIEnv *env, jobject obj, jobject surface) {// egl ------------------------------------------------------------------- startLOGD("init");ANativeWindow *nwin = ANativeWindow_fromSurface(env, surface);gl_cxt.nw = nwin;EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);if (display == EGL_NO_DISPLAY) {LOGD("egl display failed");return;}if (EGL_TRUE != eglInitialize(display, 0, 0)) {LOGD("eglInitialize failed");return;}EGLConfig eglConfig;EGLint configNum;EGLint configSpec[] = {EGL_RED_SIZE, 8,EGL_GREEN_SIZE, 8,EGL_BLUE_SIZE, 8,EGL_ALPHA_SIZE, 8,EGL_DEPTH_SIZE, 8,EGL_SURFACE_TYPE, EGL_WINDOW_BIT,EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,EGL_RECORDABLE_ANDROID, EGL_TRUE,EGL_NONE};if (EGL_TRUE != eglChooseConfig(display, configSpec, &eglConfig, 1, &configNum)) {LOGD("eglChooseConfig failed");return;}EGLSurface winSurface = eglCreateWindowSurface(display, eglConfig, nwin, 0);if (winSurface == EGL_NO_SURFACE) {LOGD("eglCreateWindowSurface failed");return;}const EGLint ctxAttr[] = {EGL_CONTEXT_CLIENT_VERSION, 2,EGL_NONE};EGLContext context = eglCreateContext(display, eglConfig, EGL_NO_CONTEXT, ctxAttr);if (context == EGL_NO_CONTEXT) {LOGD("eglCreateContext failed");return;}if (EGL_TRUE != eglMakeCurrent(display, winSurface, winSurface, context)) {LOGD("eglMakeCurrent failed");return;}gl_cxt.display = display;gl_cxt.winSurface = winSurface;gl_cxt.context = context;// egl ------------------------------------------------------------------- end// shader ------------------------------------------------------------------- startGLint vsh = initShader(vertexSimpleShape, GL_VERTEX_SHADER);GLint fsh = initShader(fragSimpleShape, GL_FRAGMENT_SHADER);GLint program = glCreateProgram();if (program == 0) {LOGD("glCreateProgram failed");return;}glAttachShader(program, vsh);glAttachShader(program, fsh);glLinkProgram(program);GLint status2 = 0;glGetProgramiv(program, GL_LINK_STATUS, &status2);if (status2 == 0) {LOGD("glLinkProgram failed");return;}gl_cxt.program = program;LOGD("glLinkProgram success");// shader ------------------------------------------------------------------- end
}static void printMat4(glm::mat4 matrix) {LOGD("\nll\n%f, %f, %f, %f\n%f, %f, %f, %f\n%f, %f, %f, %f\n%f, %f, %f, %f\n",matrix[0][0], matrix[1][0], matrix[2][0], matrix[3][0],matrix[0][1], matrix[1][1], matrix[2][1], matrix[3][1],matrix[0][2], matrix[1][2], matrix[2][2], matrix[3][2],matrix[0][3], matrix[1][3], matrix[2][3], matrix[3][3]);
}static void printVec4(glm::vec4 vec) {LOGD("\nll\n%f, %f, %f, %f\n",vec[0], vec[1], vec[2], vec[3]);
}JNIEXPORT void JNICALL Java_com_sprd_opengl_test_MyNdk4_process(JNIEnv *env, jobject obj, jobject bitmap,  jint surfaceW, jint surfaceH) {glUseProgram(gl_cxt.program);AndroidBitmapInfo bitmapInfo;if (AndroidBitmap_getInfo(env, bitmap, &bitmapInfo) < 0) {LOGE("AndroidBitmap_getInfo() failed ! ");return;}void *bmpPixels;int width = bitmapInfo.width;int height = bitmapInfo.height;LOGD("process format: %d, stride: %d", bitmapInfo.format, bitmapInfo.stride);AndroidBitmap_lockPixels(env, bitmap, &bmpPixels);unsigned int textureId;glGenTextures(1, &textureId);glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, textureId);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);LOGD("process2  4");glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, bmpPixels);unsigned char *pOri = (unsigned char *)bmpPixels;LOGD("process2  5     %d, %d, %d, %d, %d, %d, %d, %d", *(pOri), *(pOri+1), *(pOri+2), *(pOri+3),*(pOri+114), *(pOri+115), *(pOri+116), *(pOri+117));glBindTexture(GL_TEXTURE_2D, 0);AndroidBitmap_unlockPixels(env, bitmap);float DP = 0.5f;/*顶点               纹理*/float vertices[] = {-DP, -DP, DP,     0.25,  0.333,  //0DP, -DP, DP,     0.50,  0.333,  //1DP,  DP, DP,     0.50,  0.666,  //2-DP,  DP, DP,     0.25,  0.666,  //3-DP, -DP, -DP,    1.00,  0.333,  //4DP, -DP, -DP,    0.75,  0.333,  //5DP,  DP, -DP,    0.75,  0.666,  //6-DP,  DP, -DP,    1.00,  0.666,  //7-DP, -DP, -DP,    0.25,    0,    //4  8DP, -DP, -DP,      0.5,    0,    //5  9DP,  DP, -DP,      0.5,    1,    //6  10-DP,  DP, -DP,    0.25,    1,    //7  11-DP, -DP, -DP,       0,  0.333,  //4  12-DP,  DP, -DP,       0,  0.666,  //7  13};unsigned int indices[] = {0, 1, 2, 0, 2, 3,  // front1, 2, 5, 2, 5, 6,  // right4, 5, 6, 4, 6, 7,  // back0, 3, 12, 3, 12, 13, // left0, 1, 8, 1, 8, 9,  // bottom2, 3, 10, 3, 10, 11, // top};bool looper = true;int count = 0;float angleX = 0.0f;float angleY = 0.0f;float angleZ = 0.0f;
#define MAX_LEN 512float near[MAX_LEN] = {0.0f};for (int i = 0; i < MAX_LEN / 2; i++) {near[i] = 1.0f + 1.0f * i / (MAX_LEN / 2);}for (int i = 0; i < MAX_LEN / 2; i++) {near[i + MAX_LEN / 2] = 2.0f - 1.0f * i / (MAX_LEN / 2);}int sizeNear = sizeof(near) / sizeof(float);while(looper) {angleX += 0.5f;angleY += 0.6f;angleZ += 0.8f;glm::mat4 modelM = glm::mat4(1.0f);modelM = glm::scale(modelM, glm::vec3(1.0f, 1.0f, 1.0f));modelM = glm::rotate(modelM, glm::radians(angleX), glm::vec3(1.0f, 0.0f, 0.0f));modelM = glm::rotate(modelM, glm::radians(angleY), glm::vec3(0.0f, 1.0f, 0.0f));modelM = glm::rotate(modelM, glm::radians(angleZ), glm::vec3(0.0f, 0.0f, 1.0f));modelM = glm::translate(modelM, glm::vec3(0.0f, 0.0f, 0.0f));LOGD("modelM:");printMat4(modelM);glm::mat4 viewM = glm::lookAt(glm::vec3(0, 0, 2.88), // Camera is at (0,0,1), in World Space 相机位置glm::vec3(0, 0, 0), // and looks at the origin 观察点坐标glm::vec3(0, 1, 0));  // Head is up (set to 0,-1,0 to look upside-down) 相机 up 方向，即相机头部朝向LOGD("viewM:");printMat4(viewM);glm::mat4 mv = viewM*modelM;printVec4(mv*glm::vec4(-1.0, -1.0, 0, 1));printVec4(mv*glm::vec4(1.0, 1.0, 0, 1));printVec4(mv*glm::vec4(-1.0, 1.0, 0, 1));printVec4(mv*glm::vec4(1.0, -1.0, 0, 1));float ratio = 1.0f * width / height;LOGD("ratio: %f, width: %d, height: %d, surfaceW: %d, surfaceH: %d", ratio, width, height, surfaceW, surfaceH);glm::mat4 prjM;if (1.0f * height / width > 1.0f * surfaceH / surfaceW) {prjM = glm::ortho(-1.0f * width / height, 1.0f * width / height, -1.0f, 1.0f, 0.0f, 100.0f); //ratio 一般表示视口的宽高比，width/height} else {prjM = glm::ortho(-1.0f, 1.0f,-1.0f * surfaceH / (1.0f*surfaceW*height/width), 1.0f * surfaceH / (1.0f*surfaceW*height/width),3.0f, 100.0f);}prjM = glm::ortho(-1.0f, 1.0f,-1.0f, 1.0f,1.5f, 100.0f);  // 这两个值其实是负的方向更好理解printMat4(prjM);//    prjM = glm::perspective(glm::radians(45.0f), 1.0f * surfaceW / surfaceH, 2.6f, 100.f); //ratio 一般表示视口的宽高比，width/height,
//    LOGD("prjM:");
//    printMat4(prjM);prjM = glm::frustum(-1.0f, 1.0f,-1.0f, 1.0f,near[count%sizeNear], 100.f);LOGD("prjM:");printMat4(prjM);glm::mat4 mvp = prjM*viewM*modelM;printVec4(mvp*glm::vec4(-DP, -DP, DP, 1));printVec4(mvp*glm::vec4(-DP, -DP, -DP, 1));//mvp = glm::mat4(1.0f);GLint mvpLoc = glGetUniformLocation(gl_cxt.program, "u_MVPMatrix");glUniformMatrix4fv(mvpLoc, 1, GL_FALSE, (GLfloat *)&mvp[0][0]);// optimalunsigned int VBO, EBO, VAO;glGenVertexArrays(1, &VAO);glBindVertexArray(VAO);glGenBuffers(1, &VBO);glBindBuffer(GL_ARRAY_BUFFER, VBO);glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)0);glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)((0 + 3)*sizeof(float)));glEnableVertexAttribArray(0);glEnableVertexAttribArray(1);glGenBuffers(1, &EBO);glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);glBindVertexArray(0);glBindVertexArray(VAO);glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL);glEnable(GL_TEXTURE_2D);glClearColor(1.0f, 1.0f, 1.0f, 1.0f);glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);// draw to screenglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, textureId);glDrawElements(GL_TRIANGLES, sizeof(indices) / sizeof(int), GL_UNSIGNED_INT, (void*)0);glBindTexture(GL_TEXTURE_2D, 0);glDisableVertexAttribArray(0);glDisableVertexAttribArray(1);glBindVertexArray(0);eglSwapBuffers(gl_cxt.display, gl_cxt.winSurface);count++;usleep(15 * 1000);if (count == 99999) {looper = false;}}LOGD("process2 X");
}JNIEXPORT void JNICALL Java_com_sprd_opengl_test_MyNdk4_uninit(JNIEnv *env, jobject obj) {LOGD("uninit");eglDestroySurface(gl_cxt.display, gl_cxt.winSurface);eglDestroyContext(gl_cxt.display, gl_cxt.context);eglMakeCurrent(gl_cxt.display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);eglTerminate(gl_cxt.display);gl_cxt.winSurface = EGL_NO_SURFACE;gl_cxt.display = EGL_NO_DISPLAY;gl_cxt.context = EGL_NO_CONTEXT;
}

六、注意点

EGLint configSpec[] = {EGL_RED_SIZE, 8,EGL_GREEN_SIZE, 8,EGL_BLUE_SIZE, 8,EGL_ALPHA_SIZE, 8,EGL_DEPTH_SIZE, 8,EGL_SURFACE_TYPE, EGL_WINDOW_BIT,EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,EGL_RECORDABLE_ANDROID, EGL_TRUE,EGL_NONE};glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);

一定要配置 EGL_DEPTH_SIZE，我调试的时候没有配置EGL_DEPTH_SIZE（即使

glEnable(GL_DEPTH_TEST)调用了），导致绘制的立方体一直有问题，没有立体效果

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