OpenGL ES简单示例

以下是一个使用OpenGL ES 2.0的简单示例，它创建一个三角形：

#include <jni.h>
#include <errno.h>
 
#include <android/log.h>
 
#define LOGI(fmt, args...) __android_log_print(ANDROID_LOG_INFO, "native-activity", fmt, ##args)
#define LOGE(fmt, args...) __android_log_print(ANDROID_LOG_ERROR, "native-activity", fmt, ##args)
 
#include <GLES2/gl2.h>
 
GLuint gProgram;
 
static void checkGlError(const char* op) {
    for (GLint error = glGetError(); error; error = glGetError()) {
        LOGI("after %s() glError (0x%x)\n", op, error);
    }
}
 
extern "C"
JNIEXPORT void JNICALL
Java_com_example_myapp_MainActivity_init(JNIEnv* env, jobject obj, jint width, jint height) {
    const char vShaderStr[] =
            "attribute vec4 a_position;\n"
            "void main() {\n"
            "   gl_Position = a_position;\n"
            "}\n";
 
    const char fShaderStr[] =
            "precision mediump float;\n"
            "void main() {\n"
            "   gl_FragColor = vec4(0.0, 1.0, 0.0, 1.0);\n"
            "}\n";
 
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
 
    glShaderSource(vertexShader, 1, &vShaderStr, NULL);
    glShaderSource(fragmentShader, 1, &fShaderStr, NULL);
 
    GLint compiled = 0;
    glCompileShader(vertexShader);
    glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &compiled);
    if (!compiled) {
        GLint infoLen = 0;
        glGetShaderiv(vertexShader, GL_INFO_LOG_LENGTH, &infoLen);
        if (infoLen > 1) {
            char* infoLog = (char*)malloc(sizeof(char) * infoLen);
            glGetShaderInfoLog(vertexShader, infoLen, NULL, infoLog);
            LOGE("Error compiling vertex shader:%s\n", infoLog);
            free(infoLog);
        }
        glDeleteShader(vertexShader);
        return;
    }
 
    glCompileShader(fragmentShader);
    glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, &compiled);
    if (!compiled) {
        GLint infoLen = 0;
        glGetShaderiv(fragmentShader, GL_INFO_LOG_LENGTH, &infoLen);
        if (infoLen > 1) {
            char* infoLog = (char*)malloc(sizeof(char) * infoLen);
            glGetShaderInfoLog(fragmentShader, infoLen, NULL, infoLog);
            LOGE("Error compiling fragment shader:%s\n", infoLog);
            free(infoLog);
        }
        glDeleteShader(fragmentShader);