- 来源：《Computer Graphics Programming in OpenGL Using C++ 》by V Scott Gordon John L Clevenger
- 内容：程序4.1 Program 4.1 Plain Red Cube，书P78页，PDF97/403
- 相关介绍可参考 C++/OpenGL 入门(8):画一个转动的彩色立方体
- 结果，生成多个转动的彩色立方体，如下
C++/OpenGL 入门(9):复制同一立方体进行多物体运动
- 文件1：220203 4.13 redCube.cpp
#include <string>
#include <iostream>
#include <fstream>
#include <cmath>
#include "glm\glm.hpp"
#include "glm\gtc\type_ptr.hpp"
#include "glm\gtc\matrix_transform.hpp"
#include "Utils\4.1 Utils.h"
using namespace std;
#define numVAOs 1
#define numVBOs 2
float cameraX, cameraY, cameraZ;
float cubeLocX, cubeLocY, cubeLocZ;
GLuint renderingProgram;
GLuint vao[numVAOs];
GLuint vbo[numVBOs];
// allocate variables used in display() function,
// so that they won’t need to be allocated during rendering
GLuint mvLoc, projLoc;
int width, height;
float aspect;
glm::mat4 pMat, vMat, mMat, mvMat;
glm::mat4 tMat, rMat;//为了动画而添加的内容
void setupVertices(void) {
// 36 vertices, 12 triangles, makes 2x2x2 cube placed at origin
float vertexPositions[108] = {
-1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f,
1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f,
1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, -1.0f,
1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f,
1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f,
-1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f,
1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f,
-1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f,
1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f
};
glGenVertexArrays(1, vao);
glBindVertexArray(vao[0]);
glGenBuffers(numVBOs, vbo);
glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertexPositions), vertexPositions, GL_STATIC_DRAW);
}
void init(GLFWwindow* window) {
//renderingProgram = createShaderProgram("add/4.1 vertShader.glsl", "add/4.1 fragShader.glsl");
renderingProgram = createShaderProgram("add/4.12 vertShader.glsl", "add/4.12 fragShader.glsl");
cameraX = 0.0f; cameraY = 0.0f; cameraZ = 50.0f;
cubeLocX = 0.0f; cubeLocY = -2.0f; cubeLocZ = 0.0f; // shift down Y to reveal perspective
setupVertices();
}
void display(GLFWwindow* window, double currentTime) {
glClear(GL_DEPTH_BUFFER_BIT);
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT); // 每一次都将背景清理（clear）为黑色
glUseProgram(renderingProgram);
// get the uniform variables for the MV and projection matrices
mvLoc = glGetUniformLocation(renderingProgram, "mv_matrix");
projLoc = glGetUniformLocation(renderingProgram, "proj_matrix");
// build perspective matrix
glfwGetFramebufferSize(window, &width, &height);
aspect = (float)width / (float)height;
pMat = glm::perspective(1.0472f, aspect, 0.1f, 1000.0f); // 1.0472 radians = 60 degrees
// build view matrix, model matrix, and model-view matrix
for (int i = 0; i < 24; i++)
{
float tf = currentTime + i;
// ============ 以下是为了动画而添加的内容
// use current time to compute different translations in x, y, and z
tMat = glm::translate(glm::mat4(1.0f),
glm::vec3(sin(0.35f*tf)*10.0f, cos(0.52f*tf)*10.0f, sin(0.7f*tf)*10.0f));
rMat = glm::rotate(glm::mat4(1.0f), 1.75f*tf, glm::vec3(0.0f, 1.0f, 0.0f));
rMat = glm::rotate(rMat, 1.75f*tf, glm::vec3(1.0f, 0.0f, 0.0f));
rMat = glm::rotate(rMat, 1.75f*tf, glm::vec3(0.0f, 0.0f, 1.0f));
// the 1.75 adjusts the rotation speed
mMat = tMat * rMat;
// ============ 结束
vMat = glm::translate(glm::mat4(1.0f), glm::vec3(-cameraX, -cameraY, -cameraZ));
mvMat = vMat * mMat;
// copy perspective and MV matrices to corresponding uniform variables
glUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvMat));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(pMat));
// associate VBO with the corresponding vertex attribute in the vertex shader
glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);
// adjust OpenGL settings and draw model
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glDrawArrays(GL_TRIANGLES, 0, 36);
}
}
int main(void) { // main() is unchanged from before
if (!glfwInit()) { exit(EXIT_FAILURE); }
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
GLFWwindow* window = glfwCreateWindow(600, 600, "Chapter 4 - program 1", NULL, NULL);
glfwMakeContextCurrent(window);
if (glewInit() != GLEW_OK) { exit(EXIT_FAILURE); }
glfwSwapInterval(1);
init(window);
while (!glfwWindowShouldClose(window)) {
display(window, glfwGetTime());
glfwSwapBuffers(window);
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
exit(EXIT_SUCCESS);
}
- 文件2： 4.12 vertShader.glsl
（文件中放置在add文件夹中，所以cpp调用时有 add/4.1 vertShader.glsl, 可以根据需要更改）
这是生成彩色的立方体
#version 430
layout (location=0) in vec3 position;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
out vec4 varyingColor;
void main(void)
{ gl_Position = proj_matrix * mv_matrix * vec4(position,1.0);
varyingColor = vec4(position,1.0) * 0.5 + vec4(0.5, 0.5, 0.5, 0.5);
}
- 文件3： 4.12 fragShader.glsl
（文件中放置在add文件夹中，所以cpp调用时有 add/4.12 fragShader.glsl, 可以根据需要更改）
这是生成彩色的立方体
#version 430
in vec4 varyingColor;
out vec4 color;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
void main(void)
{ color = varyingColor;
}