现代OpenGL教程 04 —— 相机，向量，输入

\nglm::vec3 rightDirection = gCamera.right();　　\nglm::vec3 leftDirection = -rightDirection; //vector negation

\nconst float moveSpeed = 2.0; //units per second　　\nfloat distanceMoved = moveSpeed * secondsElapsed;\nglm::vec3 forwardDirection = gCamera.forward();　　\nglm::vec3 displacement = distanceMoved * forwardDirection; //scalar multiplication

\nglm::vec3 displacement = gCamera.forward() * moveSpeed * secondsElapsed;　　\nglm::vec3 oldPosition = gCamera.position();　　\nglm::vec3 newPosition = oldPosition + displacement; //vector addition　　\ngCamera.setPosition(newPosition);

\n// `gCamera.right()` returns a unit vector, therefore `leftDirection` will also be a unit vector.　　\n// Negation only affects the direction, not the magnitude.　　\nglm::vec3 leftDirection = -gCamera.right();　　\n//`displacement` will have a magnitude of 12　　\nglm::vec3 displacement = leftDirection * 12;　　\n//`newPosition` will be 12 units to the left of `oldPosition`　　\nglm::vec3 newPosition = oldPosition + displacement;

\nglm::vec3 someRandomVector = glm::vec3(123,456,789);　　\nglm::vec3 unitVector = glm::normalize(someRandomVector);

\nglm::mat4 Camera::matrix() const {　　\n    glm::mat4 camera = glm::perspective(_fieldOfView, _viewportAspectRatio, _nearPlane, _farPlane);　　\n    camera *= orientation();　　\n    camera = glm::translate(camera, -_position);　　\n    return camera;　　\n}\n　　\nglm::mat4 Camera::orientation() const {　　\n    glm::mat4 orientation;　　\n    orientation = glm::rotate(orientation, _verticalAngle, glm::vec3(1,0,0));　　\n    orientation = glm::rotate(orientation, _horizontalAngle, glm::vec3(0,1,0));　　\n    return orientation;　\n}

\nglm::vec3 Camera::up() const {　　\n    glm::vec4 up = glm::inverse(orientation()) * glm::vec4(0,1,0,1);　\n    return glm::vec3(up);　　\n}

\n#version 150　　\nuniform mat4 camera;　\nuniform mat4 model;　　\nin vec3 vert;　　\nin vec2 vertTexCoord;　　\nout vec2 fragTexCoord;　　\nvoid main() {　　\n    // Pass the tex coord straight through to the fragment shader　\n    fragTexCoord = vertTexCoord;　\n    // Apply all matrix transformations to vert　\n    gl_Position = camera * model * vec4(vert, 1);　\n}

\n#include "tdogl/Camera.h"

\ntdogl::Camera gCamera;

\nstatic void LoadShaders() {　　\n    std::vector shaders;\n    shaders.push_back(tdogl::Shader::shaderFromFile(ResourcePath("vertex-shader.txt"), GL_VERTEX_SHADER));　　\n    shaders.push_back(tdogl::Shader::shaderFromFile(ResourcePath("fragment-shader.txt"), GL_FRAGMENT_SHADER));　\n    gProgram = new tdogl::Program(shaders);\n    // the commented-out code below was removed　\n    /* 　\n    gProgram->use();　\n    //set the "projection" uniform in the vertex shader, because it's not going to change　\n    glm::mat4 projection = glm::perspective(50.0, SCREEN_SIZE.x/SCREEN_SIZE.y, 0.1, 10.0);\n    //glm::mat4 projection = glm::ortho(-2, 2, -2, 2, 0.1, 10);　\n    gProgram->setUniform("projection", projection);　　\n    //set the "camera" uniform in the vertex shader, because it's also not going to change　\n    glm::mat4 camera = glm::lookAt(glm::vec3(3,3,3), glm::vec3(0,0,0), glm::vec3(0,1,0));　\n    gProgram->setUniform("camera", camera);　\n    gProgram->stopUsing();　\n    */　\n}

\n// draws a single frame　　\nstatic void Render() {　\n    // clear everything　\n    glClearColor(0, 0, 0, 1); // black　\n    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);\n    // bind the program (the shaders)　\n    gProgram->use();　　\n    // set the "camera" uniform　　\n    gProgram->setUniform("camera", gCamera.matrix());

\ngCamera.setPosition(glm::vec3(0,0,4));　　\ngCamera.setViewportAspectRatio(SCREEN_SIZE.x / SCREEN_SIZE.y);

\n// update the scene based on the time elapsed since last update　　\nvoid Update(float secondsElapsed) {　\n    //rotate the cube　　\n    const GLfloat degreesPerSecond = 180.0f;　\n    gDegreesRotated += secondsElapsed * degreesPerSecond;　\n    while(gDegreesRotated > 360.0f) gDegreesRotated -= 360.0f;　\n    //move position of camera based on WASD keys　\n    const float moveSpeed = 2.0; //units per second　\n    if(glfwGetKey(gWindow, 'S')){　\n        gCamera.offsetPosition(secondsElapsed * moveSpeed * -gCamera.forward());　　\n    } else if(glfwGetKey(gWindow, 'W')){　\n        gCamera.offsetPosition(secondsElapsed * moveSpeed * gCamera.forward());　\n    }　　\n    if(glfwGetKey(gWindow, 'A')){　　\n        gCamera.offsetPosition(secondsElapsed * moveSpeed * -gCamera.right());　　\n    } else if(glfwGetKey(gWindow, 'D')){　　\n        gCamera.offsetPosition(secondsElapsed * moveSpeed * gCamera.right());　　\n    }　　\n}

\ngCamera.offsetPosition(secondsElapsed * moveSpeed * -gCamera.forward());

\nvoid MoveCameraBackwards(float secondsElapsed) {　　\n    //TODO: finish writing this function　　\n}

\nvoid MoveCameraBackwards(float secondsElapsed) {　　\n    //`direction` is a unit vector, set to the "backwards" direction　\n    glm::vec3 direction = -gCamera.forward();　　\n    //TODO: finish writing this function　　\n}

\nvoid MoveCameraBackwards(float secondsElapsed) {　　\n    //`direction` is a unit vector, set to the "backwards" direction　\n    glm::vec3 direction = -gCamera.forwards();　　\n    //`distance` is the total distance to move the camera　　\n    float distance = moveSpeed * secondsElapsed;　　\n    //TODO: finish writing this function　　\n}

\nvoid MoveCameraBackwards(float secondsElapsed) {　　\n    //`direction` is a unit vector, set to the "backwards" direction　　\n    glm::vec3 direction = -gCamera.forwards(); //vector negation　　\n    //`distance` is the total distance to move the camera　　\n    float distance = moveSpeed * secondsElapsed;　　\n    //`displacement` is a combination of `distance` and `direction`　　\n    glm::vec3 displacement = distance * direction; //scalar multiplication　　\n    //TODO: finish writing this function　\n}

\nvoid MoveCameraBackwards(float secondsElapsed) {　　\n    //`direction` is a unit vector, set to the "backwards" direction　　\n    glm::vec3 direction = -gCamera.forwards(); //vector negation　\n    //`distance` is the total distance to move the camera　　\n    float distance = moveSpeed * secondsElapsed;　　\n    //`displacement` is a combination of `distance` and `direction`　　\n    glm::vec3 displacement = distance * direction; //scalar multiplication　　\n    //change the position of the camera　　\n    glm::vec3 oldPosition = gCamera.position();　　\n    glm::vec3 newPosition = oldPosition + displacement; //vector addition　　\n    gCamera.setPosition(newPosition);　　\n}

\ngCamera.offsetPosition(secondsElapsed * moveSpeed * -gCamera.forward());

\nif(glfwGetKey(gWindow, 'Z')){　　\n    gCamera.offsetPosition(secondsElapsed * moveSpeed * -glm::vec3(0,1,0));　　\n} else if(glfwGetKey(gWindow, 'X')){　　\n    gCamera.offsetPosition(secondsElapsed * moveSpeed * glm::vec3(0,1,0));　　\n}

\n// run while the window is open　　\ndouble lastTime = glfwGetTime();　　\nwhile(!glfwWindowShouldClose(gWindow)){　　\n    // process pending events　　\n    glfwPollEvents();　　\n    // update the scene based on the time elapsed since last update　　\n    double thisTime = glfwGetTime();　　\n    Update((float)(thisTime - lastTime));　\n    lastTime = thisTime;　　\n    // draw one frame　　\n    Render();　　\n    // check for errors　　\n    GLenum error = glGetError();　\n    if(error != GL_NO_ERROR)　\n        std::cerr 　　\n    //exit program if escape key is pressed　\n    if(glfwGetKey(gWindow, GLFW_KEY_ESCAPE))　　\n        glfwSetWindowShouldClose(gWindow, GL_TRUE);　　\n}

\n// GLFW settings　　\nglfwSetInputMode(gWindow, GLFW_CURSOR, GLFW_CURSOR_DISABLED);　　\nglfwSetCursorPos(gWindow, 0, 0);

\n//rotate camera based on mouse movement　　\nconst float mouseSensitivity = 0.1f;　　\ndouble mouseX, mouseY;　　\nglfwGetCursorPos(gWindow, &mouseX, &mouseY);　　\ngCamera.offsetOrientation(mouseSensitivity * (float)mouseY, mouseSensitivity * (float)mouseX);　\nglfwSetCursorPos(gWindow, 0, 0); //reset the mouse, so it doesn't go out of the window

\ndouble gScrollY = 0.0;

\n// records how far the y axis has been scrolled　　\nvoid OnScroll(GLFWwindow* window, double deltaX, double deltaY) {　　\n  gScrollY += deltaY;　　\n}

\nglfwSetScrollCallback(gWindow, OnScroll);

\nconst float zoomSensitivity = -0.2f;　　\nfloat fieldOfView = gCamera.fieldOfView() + zoomSensitivity * (float)gScrollY;　　\nif(fieldOfView 　　\nif(fieldOfView > 130.0f) fieldOfView = 130.0f;　　\ngCamera.setFieldOfView(fieldOfView);　　\ngScrollY = 0;