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尝试集成2个OpenGL程序。我的圆圈没有以我想要的方式出现在我的其他程序中

glm-math opengl
  •  1
  • Zolly  · 技术社区  · 7 年前

    • 其中一个显示2D空心红色圆圈
    • 另一个是 3D "planet system" (有立方体围绕“太阳”移动/旋转)

    我注意到,当我取消注释这些代码段(如下)时,会出现圆圈,但 it moves around just like a planet . 

    static void init(GLFWwindow* window){
    /*------------------------Circle----------------------*/

        //// generate vertices of triangle fan
        //generate_circle();

        //// create VBO and buffer the data
        //glGenBuffers(1, &g_VBO[1]);
        //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[1]);
        //glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * (g_slices + 2), g_vertices_circle, GL_STATIC_DRAW);

        //glGenBuffers(1, &g_VBO[2]);
        //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[2]);
        //glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * (g_slices + 2), g_colors_circle, GL_STATIC_DRAW);

        //// create VAO and specify VBO data
        //glGenVertexArrays(1, &g_VAO[1]);
        //glBindVertexArray(g_VAO[1]);
        //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[1]);
        //glVertexAttribPointer(positionIndex, 3, GL_FLOAT, GL_FALSE, 0, 0);    // specify the form of the data
        //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[2]);
        //glVertexAttribPointer(colorIndex, 3, GL_FLOAT, GL_FALSE, 0, 0);   // specify the form of the data

        /*----------------------------------------------------*/
}


static void render_scene(){
    //  glBindVertexArray(g_VAO[1]);            // make VAO active
    //
    ////Circle 1
    //  glDrawArrays(GL_LINE_LOOP, 0, g_slices + 2);    // display the vertices based on the primitive type
    //
    //  glBindVertexArray(g_VAO[0]);        // make VAO active
}


    #version 330 core

// input data (different for all executions of this shader)
in vec3 aPosition;
in vec3 aColor;

// ModelViewProjection matrix
uniform mat4 uModelViewProjectionMatrix;

// output data (will be interpolated for each fragment)
out vec3 vColor;

void main()
{
    // set vertex position
    gl_Position = uModelViewProjectionMatrix * vec4(aPosition, 1.0);

    // the color of each vertex will be interpolated
    // to produce the color of each fragment
    vColor = aColor;
}

    这是我的主要节目: 

    #include <cstdio>       // for C++ i/o
#include <iostream>
#include <string>
#include <cstddef>
using namespace std;    // to avoid having to use std::

#define GLEW_STATIC     // include GLEW as a static library
#include <GLEW/glew.h>  // include GLEW
#include <GLFW/glfw3.h> // include GLFW (which includes the OpenGL header)
#include <glm/glm.hpp>  // include GLM (ideally should only use the GLM headers that are actually used)
#include <glm/gtx/transform.hpp>
using namespace glm;    // to avoid having to use glm::

#include "shader.h"

#define PI 3.14159265
#define MAX_SLICES 50
#define MIN_SLICES 8
#define MAX_VERTICES (MAX_SLICES+2)*3   // a triangle fan should have a minimum of 3 vertices
#define CIRCLE_RADIUS 1.0
#define WINDOW_WIDTH 1500
#define WINDOW_HEIGHT 800

// struct for vertex attributes
struct Vertex
{
    GLfloat position[3];
    GLfloat color[3];
};

// global variables

GLfloat g_vertices_circle[MAX_VERTICES] = {
    0.0f, 0.0f, 0.0f,       // try adjusting this value to get rid of red line
    0.0f, 0.0f, 0.0f
};

GLfloat g_colors_circle[MAX_VERTICES] = {
    1.0f, 0.0f, 0.0f,
    1.0f, 0.0f, 0.0f
};

GLuint g_slices = MAX_SLICES;   // number of circle slices

Vertex g_vertices[] = {
    // vertex 1
    -0.5f, 0.5f, 0.5f,  // position
    1.0f, 0.0f, 1.0f,   // colour
    // vertex 2
    -0.5f, -0.5f, 0.5f, // position
    1.0f, 0.0f, 0.0f,   // colour
    // vertex 3
    0.5f, 0.5f, 0.5f,   // position
    1.0f, 1.0f, 1.0f,   // colour
    // vertex 4
    0.5f, -0.5f, 0.5f,  // position
    1.0f, 1.0f, 0.0f,   // colour
    // vertex 5
    -0.5f, 0.5f, -0.5f, // position
    0.0f, 0.0f, 1.0f,   // colour
    // vertex 6
    -0.5f, -0.5f, -0.5f,// position
    0.0f, 0.0f, 0.0f,   // colour
    // vertex 7
    0.5f, 0.5f, -0.5f,  // position
    0.0f, 1.0f, 1.0f,   // colour
    // vertex 8
    0.5f, -0.5f, -0.5f, // position
    0.0f, 1.0f, 0.0f,   // colour
};

GLuint g_indices[] = {
    0, 1, 2,    // triangle 1
    2, 1, 3,    // triangle 2
    4, 5, 0,    // triangle 3
    0, 5, 1,    // ...
    2, 3, 6,
    6, 3, 7,
    4, 0, 6,
    6, 0, 2,
    1, 5, 3,
    3, 5, 7,
    5, 4, 7,
    7, 4, 6,    // triangle 12
};

GLuint g_IBO = 0;               // index buffer object identifier
GLuint g_VBO[3];                // vertex buffer object identifier
GLuint g_VAO[2];                // vertex array object identifier
GLuint g_shaderProgramID = 0;   // shader program identifier
GLuint g_MVP_Index = 0;         // location in shader
glm::mat4 g_modelMatrix[5];     // object model matrices
glm::mat4 g_viewMatrix;         // view matrix
glm::mat4 g_projectionMatrix;   // projection matrix

float g_orbitSpeed[5] = { 0.3f, 1.0f, 0.7f, 0.9f, 1.2f };       // for speed of rotation around sun
float g_rotationSpeed[5] = { 0.07f, 0.7f, 3.0f, 5.0f, 1.0f };   // for speed of rotation on own axis
float g_scaleSize[5] = { 0.5f, 0.5f, 0.5f, 0.5f, 0.5f };        // for scaling the orbiting planets
float g_axisOfRotation[5] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, };  // for offsetting the axis of rotation

void generate_circle()
{
    float angle = PI * 2 / static_cast<float>(g_slices);    // used to generate x and y coordinates
    float scale_factor = static_cast<float>(WINDOW_HEIGHT) / WINDOW_WIDTH;  // scale to make it a circle instead of an elipse
    int index = 0;  // vertex index

    g_vertices_circle[3] = CIRCLE_RADIUS * scale_factor;    // set x coordinate of vertex 1

                                                            // generate vertex coordinates for triangle fan
    for (int i = 2; i < g_slices + 2; i++)
    {
        // multiply by 3 because a vertex has x, y, z coordinates
        index = i * 3;

        g_vertices_circle[index] = CIRCLE_RADIUS * cos(angle) * scale_factor;
        g_vertices_circle[index + 1] = CIRCLE_RADIUS * sin(angle);
        g_vertices_circle[index + 2] = 0.0f;

        //Color for edges. See stackoverflow
        g_colors_circle[index] = 1.0f;
        g_colors_circle[index + 1] = 0.0f;
        g_colors_circle[index + 2] = 0.0f;

        // update to next angle
        angle += PI * 2 / static_cast<float>(g_slices);
    }

    // Gets rid of line from middle of circle
    g_vertices_circle[0] = g_vertices_circle[3];
    g_vertices_circle[1] = g_vertices_circle[4];
    g_vertices_circle[2] = g_vertices_circle[5];
}

static void init(GLFWwindow* window)
{
    glClearColor(0.0, 0.0, 0.0, 1.0);   // set clear background colour

    glEnable(GL_DEPTH_TEST);    // enable depth buffer test

    // create and compile our GLSL program from the shader files
    g_shaderProgramID = loadShaders("MVP_VS.vert", "ColorFS.frag");

    // enable point size
    glEnable(GL_PROGRAM_POINT_SIZE);
    // set line width
    glLineWidth(5.0);

    // find the location of shader variables
    GLuint positionIndex = glGetAttribLocation(g_shaderProgramID, "aPosition");
    GLuint colorIndex = glGetAttribLocation(g_shaderProgramID, "aColor");
    g_MVP_Index = glGetUniformLocation(g_shaderProgramID, "uModelViewProjectionMatrix");

    // initialise model matrix to the identity matrix
    g_modelMatrix[0] = g_modelMatrix[1] = g_modelMatrix[2] = g_modelMatrix[3] = g_modelMatrix[4] = glm::mat4(1.0f);

    // initialise view matrix
    g_viewMatrix = glm::lookAt(glm::vec3(10, 3, 8), glm::vec3(0, 0, 0), glm::vec3(0, 1, 0));    //perspective

    int width, height;
    glfwGetFramebufferSize(window, &width, &height);
    float aspectRatio = static_cast<float>(width) / height;

    // initialise projection matrix
    g_projectionMatrix = glm::perspective(45.0f, aspectRatio, 0.1f, 100.0f);

    // generate identifier for VBO and copy data to GPU
    glGenBuffers(1, &g_VBO[0]);
    glBindBuffer(GL_ARRAY_BUFFER, g_VBO[0]);
    glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertices), g_vertices, GL_STATIC_DRAW);

    // generate identifier for IBO and copy data to GPU
    glGenBuffers(1, &g_IBO);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_IBO);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(g_indices), g_indices, GL_STATIC_DRAW);

    // generate identifiers for VAO
    glGenVertexArrays(1, &g_VAO[0]);

    // create VAO and specify VBO data
    glBindVertexArray(g_VAO[0]);
    glBindBuffer(GL_ARRAY_BUFFER, g_VBO[0]);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, g_IBO);
    // interleaved attributes
    glVertexAttribPointer(positionIndex, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), reinterpret_cast<void*>(offsetof(Vertex, position)));
    glVertexAttribPointer(colorIndex, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), reinterpret_cast<void*>(offsetof(Vertex, color)));

    /*------------------------Circle----------------------*/

    //// generate vertices of triangle fan
    //generate_circle();

    //// create VBO and buffer the data
    //glGenBuffers(1, &g_VBO[1]);
    //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[1]);
    //glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * (g_slices + 2), g_vertices_circle, GL_STATIC_DRAW);

    //glGenBuffers(1, &g_VBO[2]);
    //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[2]);
    //glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 3 * (g_slices + 2), g_colors_circle, GL_STATIC_DRAW);

    //// create VAO and specify VBO data
    //glGenVertexArrays(1, &g_VAO[1]);
    //glBindVertexArray(g_VAO[1]);
    //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[1]);
    //glVertexAttribPointer(positionIndex, 3, GL_FLOAT, GL_FALSE, 0, 0);    // specify the form of the data
    //glBindBuffer(GL_ARRAY_BUFFER, g_VBO[2]);
    //glVertexAttribPointer(colorIndex, 3, GL_FLOAT, GL_FALSE, 0, 0);   // specify the form of the data

    /*----------------------------------------------------*/

    glEnableVertexAttribArray(positionIndex);   // enable vertex attributes
    glEnableVertexAttribArray(colorIndex);
}

//Generates a random value between 0.1 and 0.9
double generateRandomFloat(float min, float max) 
{
    return min + static_cast <float> (rand()) / (static_cast <float> (RAND_MAX / (max - min)));
}

// function used to update the scene
static void update_scene()
{
    // static variables for rotation angles
    static float orbitAngle[5] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, };
    static float rotationAngle[5] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
    float scaleFactor = 0.05;

    orbitAngle[0] += g_orbitSpeed[0] * scaleFactor;
    orbitAngle[1] += g_orbitSpeed[1] * scaleFactor;
    orbitAngle[2] += g_orbitSpeed[2] * scaleFactor;
    orbitAngle[3] += g_orbitSpeed[3] * scaleFactor;
    orbitAngle[4] += g_orbitSpeed[4] * scaleFactor;

    // update rotation angles
    rotationAngle[0] += g_rotationSpeed[0] * scaleFactor;
    rotationAngle[1] += g_rotationSpeed[1] * scaleFactor;
    rotationAngle[2] += g_rotationSpeed[2] * scaleFactor;
    rotationAngle[3] += g_rotationSpeed[3] * scaleFactor;
    rotationAngle[4] += g_rotationSpeed[4] * scaleFactor;

    // update model matrix
    g_modelMatrix[0] = glm::rotate(rotationAngle[0], glm::vec3(0.0f, 1.0f, 0.0f));

    g_modelMatrix[1] = glm::translate(glm::vec3(g_axisOfRotation[1], 0.0f, 0.0f))   //moves the axis of rotation along x-axis
        * glm::rotate(orbitAngle[1], glm::vec3(0.0f, 1.0f, 0.0f))
        * glm::translate(glm::vec3(2.0f, 0.0f, 0.0f))
        * glm::rotate(rotationAngle[1], glm::vec3(0.0f, -1.0f, 0.0f))       //enables rotation on own axis. try comment
        * glm::rotate(glm::radians(45.0f), glm::vec3(1.0f, 0.0f, 0.0f))     //rotates into a diamond shape
        * glm::rotate(glm::radians(45.0f), glm::vec3(0.0f, 0.0f, 1.0f))     //rotates into a diamond shape
        * glm::scale(glm::vec3(g_scaleSize[1], g_scaleSize[1], g_scaleSize[1]));

    g_modelMatrix[2] = glm::translate(glm::vec3(g_axisOfRotation[2], 0.0f, 0.0f))
        * glm::rotate(orbitAngle[2], glm::vec3(0.0f, -1.0f, 0.0f))
        * glm::translate(glm::vec3(4.0f, 0.0f, 0.0f))
        * glm::rotate(rotationAngle[2], glm::vec3(0.0f, 1.0f, 0.0f))
        * glm::scale(glm::vec3(g_scaleSize[2], g_scaleSize[2], g_scaleSize[2]));

    g_modelMatrix[3] = glm::translate(glm::vec3(g_axisOfRotation[3], 0.0f, 0.0f))
        * glm::rotate(orbitAngle[3], glm::vec3(0.0f, 1.0f, 0.0f))
        * glm::translate(glm::vec3(6.0f, 0.0f, 0.0f))
        * glm::rotate(rotationAngle[3], glm::vec3(0.0f, 1.0f, 0.0f))
        * glm::scale(glm::vec3(g_scaleSize[3], g_scaleSize[3], g_scaleSize[3]));

    g_modelMatrix[4] = glm::translate(glm::vec3(g_axisOfRotation[4], 0.0f, 0.0f))
        * glm::rotate(orbitAngle[4], glm::vec3(0.0f, -1.0f, 0.0f))  // -y changes orbit to clock-wise
        * glm::translate(glm::vec3(8.0f, 0.0f, 0.0f))
        * glm::rotate(rotationAngle[4], glm::vec3(0.0f, -1.0f, 0.0f))
        * glm::scale(glm::vec3(g_scaleSize[4], g_scaleSize[4], g_scaleSize[4]));
}

// function used to render the scene
static void render_scene()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear colour buffer and depth buffer

    glUseProgram(g_shaderProgramID);    // use the shaders associated with the shader program

//  glBindVertexArray(g_VAO[1]);            // make VAO active
//
////Circle 1
//  glDrawArrays(GL_LINE_LOOP, 0, g_slices + 2);    // display the vertices based on the primitive type
//
//  glBindVertexArray(g_VAO[0]);        // make VAO active

// Object 1
    glm::mat4 MVP = g_projectionMatrix * g_viewMatrix * g_modelMatrix[0];
    // set uniform model transformation matrix
    glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);

    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);   // display the vertices based on their indices and primitive type

// Object 2
    MVP = g_projectionMatrix * g_viewMatrix * g_modelMatrix[1];
    glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);   // display the vertices based on their indices and primitive type

// Object 3
    MVP = g_projectionMatrix * g_viewMatrix * g_modelMatrix[2];
    glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);   // display the vertices based on their indices and primitive type

// Object 4
    MVP = g_projectionMatrix * g_viewMatrix * g_modelMatrix[3];
    glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);   // display the vertices based on their indices and primitive type

// Object 5
    MVP = g_projectionMatrix * g_viewMatrix * g_modelMatrix[4];
    glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);   // display the vertices based on their indices and primitive type

    glFlush();  // flush the pipeline
}

int main(void)
{
    GLFWwindow* window = NULL;  // pointer to a GLFW window handle

    glfwSetErrorCallback(error_callback);   // set error callback function

    // initialise GLFW
    if (!glfwInit())
    {
        // if failed to initialise GLFW
        exit(EXIT_FAILURE);
    }

    // minimum OpenGL version 3.3
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);

    // create a window and its OpenGL context
    window = glfwCreateWindow(1500, 1000, "Assignment 2", NULL, NULL);

    // if failed to create window
    if (window == NULL)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    glfwMakeContextCurrent(window); // set window context as the current context
    glfwSwapInterval(1);            // swap buffer interval

    // initialise GLEW
    if (glewInit() != GLEW_OK)
    {
        // if failed to initialise GLEW
        cerr << "GLEW initialisation failed" << endl;
        exit(EXIT_FAILURE);
    }

    // set key callback function
    glfwSetKeyCallback(window, key_callback);

    // initialise rendering states
    init(window);

    // variables for simple time management
    float lastUpdateTime = glfwGetTime();
    float currentTime = lastUpdateTime;

    // the rendering loop
    while (!glfwWindowShouldClose(window))
    {
        currentTime = glfwGetTime();

        // only update if more than 0.02 seconds since last update
        if (currentTime - lastUpdateTime > 0.02)
        {
            update_scene();     // update the scene
            render_scene();     // render the scene

            glfwSwapBuffers(window);    // swap buffers
            glfwPollEvents();           // poll for events

            lastUpdateTime = currentTime;   // update last update time
        }
    }

    // clean up
    glDeleteProgram(g_shaderProgramID);
    glDeleteBuffers(1, &g_IBO);
    glDeleteBuffers(1, &g_VBO[0]);
    glDeleteBuffers(1, &g_VBO[1]);
    glDeleteVertexArrays(1, &g_VAO[0]);
    glDeleteVertexArrays(1, &g_VAO[1]);

    // close the window and terminate GLFW
    glfwDestroyWindow(window);
    glfwTerminate();

    exit(EXIT_SUCCESS);
}
    1 回复  |  直到 7 年前
        1
  •  1
  •   Rabbid76    7 年前

    你必须设置均匀变量 uModelViewProjectionMatrix 在你画圆之前。 对于所有其他对象,您设置了适当的模型视图投影矩阵,但对圆不这样做。 由于圆不移动并且没有其他位置数据,因此您只需要投影矩阵和视图矩阵。 在这种情况下,模型矩阵是单位矩阵,因此可以跳过它。 

    glm::mat4 MVP = g_projectionMatrix * g_viewMatrix;
glUniformMatrix4fv(g_MVP_Index, 1, GL_FALSE, &MVP[0][0]);
glBindVertexArray(g_VAO[1]);
glDrawArrays(GL_LINE_LOOP, 0, g_slices + 2);


    glm::vec3 circlePos = ....;
glm::mat4 circleModelMat = glm::translate(glm::mat4(1.0f), circlePos);
glm::mat4 MVP = g_projectionMatrix * g_viewMatrix * circleModelMat;

    答案的扩展:

    然而,我的立方体仍然不见了。我只能看到一个静止的圆。 你知道如何让立方体也出现吗? 

    glBindVertexArray(g_VAO[0]);
// ... bind buffer and set vetex attribute pointer
glEnableVertexAttribArray(positionIndex);   // enable vertex attributes
glEnableVertexAttribArray(colorIndex);

/*------------------------Circle----------------------*/
// ...
glBindVertexArray(g_VAO[1]);
// ... bind buffer and set vetex attribute pointer
glEnableVertexAttribArray(positionIndex);   // enable vertex attributes
glEnableVertexAttribArray(colorIndex);
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