Question

所以，我试图在openGL和GLFW中绘制一个简单的多维数据集。

在下面的代码中，我可以绘制立方体，但它只是一个简单的矩形。这里发生了什么？

我尝试过“glTransformf（0,0，-10）;”但是如果我做的事情少于-2，那么立方体会消失。在-2，正面出现。在默认位置0，我可以看到立方体的背面。

另外，当我尝试旋转它时，显示的所有内容都是一个从窗口顶部移动到底部的矩形。看起来很奇怪。

任何人都可以帮我找出程序这样做的原因吗？

#if defined(_WIN32) || defined(_WIN64)
#include <windows.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <fstream>

#define GLEW_STATIC
#include <GL/glew.h>
#include <GL/gl.h>
#include <GLFW/glfw3.h>

const char* gameTitle = "TEST";
GLFWwindow* window;

GLfloat vertices[] =
{
-1, -1, -1,   -1, -1,  1,   -1,  1,  1,   -1,  1, -1,
 1, -1, -1,    1, -1,  1,    1,  1,  1,    1,  1, -1,
-1, -1, -1,   -1, -1,  1,    1, -1,  1,    1, -1, -1,
-1,  1, -1,   -1,  1,  1,    1,  1,  1,    1,  1, -1,
-1, -1, -1,   -1,  1, -1,    1,  1, -1,    1, -1, -1,
-1, -1,  1,   -1,  1,  1,    1,  1,  1,    1, -1,  1
};

GLfloat colors[] =
{
0, 0, 0,   0, 0, 1,   0, 1, 1,   0, 1, 0,
1, 0, 0,   1, 0, 1,   1, 1, 1,   1, 1, 0,
0, 0, 0,   0, 0, 1,   1, 0, 1,   1, 0, 0,
0, 1, 0,   0, 1, 1,   1, 1, 1,   1, 1, 0,
0, 0, 0,   0, 1, 0,   1, 1, 0,   1, 0, 0,
0, 0, 1,   0, 1, 1,   1, 1, 1,   1, 0, 1
};

static void controls(GLFWwindow* window, int key, int scancode, int action, int mods)
{
if(action == GLFW_PRESS)
    if(key == GLFW_KEY_ESCAPE)
        glfwSetWindowShouldClose(window, GL_TRUE);
}

bool initWindow(const int resX, const int resY)
{
if(!glfwInit())
{
    fprintf(stderr, "Failed to initialize GLFW\n");
    return false;
}
glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing

// Open a window and create its OpenGL context
window = glfwCreateWindow(resX, resY, gameTitle, NULL, NULL);

if(window == NULL)
{
    fprintf(stderr, "Failed to open GLFW window.\n");
    glfwTerminate();
    return false;
}

glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, controls);

// Get info of GPU and supported OpenGL version
printf("Renderer: %s\n", glGetString(GL_RENDERER));
printf("OpenGL version supported %s\n", glGetString(GL_VERSION));

glEnable(GL_DEPTH_TEST); // Depth Testing
glDepthFunc(GL_LEQUAL);
glDisable(GL_CULL_FACE);
glCullFace(GL_BACK);
return true;
}

static void drawCube()
{
static float alpha = 0;
glMatrixMode(GL_PROJECTION_MATRIX);
glLoadIdentity();
glTranslatef(0,0,-2);
glMatrixMode(GL_MODELVIEW_MATRIX);
//attempt to rotate cube
//glRotatef(alpha, 1, 0, 0);

/* We have a color array and a vertex array */
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glColorPointer(3, GL_FLOAT, 0, colors);

/* Send data : 24 vertices */
glDrawArrays(GL_QUADS, 0, 24);

/* Cleanup states */
glDisableClientState(GL_COLOR_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
alpha += 0.1;
}

static void display()
{
glClearColor(0.0, 0.8, 0.3, 1.0);
while(!glfwWindowShouldClose(window))
{
    // Draw stuff
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    drawCube();

    // Update Screen
    //glFlush();
    glfwSwapBuffers(window);

    // Check for any input, or window movement
    glfwPollEvents();

    // Scale to window size
    GLint windowWidth, windowHeight;
    glfwGetWindowSize(window, &windowWidth, &windowHeight);
    glViewport(0, 0, windowWidth, windowHeight);
}
}

int main(int argc, char** argv)
{
if(initWindow(1024, 620))
{
    display();
}
printf("Goodbye!\n");
glfwDestroyWindow(window);
glfwTerminate();
return 0;
}

Answer 1

全球比赛很糟糕。
您从未设置（有意义的）投影矩阵。
Abuse not the projection matrix stack。
不要将您的矩阵设置为drawCube()，单一责任原则以及所有这些。
在尝试绘制之前设置您的视口。

C ++有c - C标头的前缀版本（stdio.h - ＆gt; cstdio）。请改用它们。

所有在一起：

#include <GL/glew.h> #include <GLFW/glfw3.h> #include <cstdio> void controls(GLFWwindow* window, int key, int scancode, int action, int mods) { if(action == GLFW_PRESS) if(key == GLFW_KEY_ESCAPE) glfwSetWindowShouldClose(window, GL_TRUE); } GLFWwindow* initWindow(const int resX, const int resY) { if(!glfwInit()) { fprintf(stderr, "Failed to initialize GLFW\n"); return NULL; } glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing // Open a window and create its OpenGL context GLFWwindow* window = glfwCreateWindow(resX, resY, "TEST", NULL, NULL); if(window == NULL) { fprintf(stderr, "Failed to open GLFW window.\n"); glfwTerminate(); return NULL; } glfwMakeContextCurrent(window); glfwSetKeyCallback(window, controls); // Get info of GPU and supported OpenGL version printf("Renderer: %s\n", glGetString(GL_RENDERER)); printf("OpenGL version supported %s\n", glGetString(GL_VERSION)); glEnable(GL_DEPTH_TEST); // Depth Testing glDepthFunc(GL_LEQUAL); glDisable(GL_CULL_FACE); glCullFace(GL_BACK); return window; } void drawCube() { GLfloat vertices[] = { -1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, 1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1, 1, 1, -1, 1, 1, -1, -1, -1, 1, -1, -1, 1, 1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, 1, -1, 1, 1, -1, 1, -1, -1, -1, -1, 1, -1, 1, 1, 1, 1, 1, 1, -1, 1 }; GLfloat colors[] = { 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1 }; static float alpha = 0; //attempt to rotate cube glRotatef(alpha, 0, 1, 0); /* We have a color array and a vertex array */ glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_COLOR_ARRAY); glVertexPointer(3, GL_FLOAT, 0, vertices); glColorPointer(3, GL_FLOAT, 0, colors); /* Send data : 24 vertices */ glDrawArrays(GL_QUADS, 0, 24); /* Cleanup states */ glDisableClientState(GL_COLOR_ARRAY); glDisableClientState(GL_VERTEX_ARRAY); alpha += 1; } void display( GLFWwindow* window ) { while(!glfwWindowShouldClose(window)) { // Scale to window size GLint windowWidth, windowHeight; glfwGetWindowSize(window, &windowWidth, &windowHeight); glViewport(0, 0, windowWidth, windowHeight); // Draw stuff glClearColor(0.0, 0.8, 0.3, 1.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_PROJECTION_MATRIX); glLoadIdentity(); gluPerspective( 60, (double)windowWidth / (double)windowHeight, 0.1, 100 ); glMatrixMode(GL_MODELVIEW_MATRIX); glTranslatef(0,0,-5); drawCube(); // Update Screen glfwSwapBuffers(window); // Check for any input, or window movement glfwPollEvents(); } } int main(int argc, char** argv) { GLFWwindow* window = initWindow(1024, 620); if( NULL != window ) { display( window ); } glfwDestroyWindow(window); glfwTerminate(); return 0; }

Answer 2

我相信你的问题在于你基本上使用的是正交投影，或者肯定是不是透视的东西，这将使立方体更多地使用＆＃34; 3D＆＃34;外表我认为你正在寻找。

尝试以下内容设置正确的透视投影矩阵：

glMatrixMode(GL_PROJECTION_MATRIX);
glLoadIdentity();
gluPerspective(45, windowWidth / windowHeight, 0.1f, 100.0f);

// Draw calls.

C ++ OpenGL，GLFW绘制一个简单的立方体

2 个答案: