Question

我正在尝试仅使用gldrawpixels（）（和glfw）编写自己的光栅化器。我不能使用opengl 3或4的东西，因为我的笔记本电脑只有intelgraphics。我想保持我的代码跨平台所以没有windows.h。我不能使用pixeltoaster，因为它不是建立在mingw上。当我运行我的程序时崩溃为什么？我不知道哪个函数会导致错误。

这是我的代码：

我的main.cpp：

#include "main.h"



GLFWwindow* window;

unsigned int x ,y,size;

float* pixeldata;


// init
bool init()
{
bool init_val;
if(!glfwInit() )
{
    std::cout << "GLFW failed to initialize \n";
        init_val = false;
        glfwTerminate();
        return init_val;
}
init_val = true;
return init_val;
}
//creat window and allocate memory for pixelbuffer
int createwindow(int width, int height, char* window_name, int fullscreen)
{
x = width;
y = height;

size = x*y;
pixeldata = new float[size*3];
std::cout << size;
    if (fullscreen == 1)
        {
            window = glfwCreateWindow( width, height, window_name ,glfwGetPrimaryMonitor(),NULL );
        }

    else
        {
            window = glfwCreateWindow( width, height, window_name ,NULL,NULL );
        }
    if(!window)
        {
            std::cout << "failed to open window! \n";
                glfwTerminate();
                return -1;
        }

    else
        {
            glfwMakeContextCurrent(window);
        }
}
//places pixel on screen, doesn't work properly
void setpixel(unsigned int xloc,unsigned int yloc)
{
    unsigned int pixloc;
    pixloc = xloc * yloc;
        if(pixloc > size)
            {
                std::cout << "TOO FAR!";
                glfwWindowShouldClose(window);
                glfwTerminate();

            }
        else
            {
            pixeldata[pixloc*3] = 10;
            }

}


void render()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glDrawPixels(x, y, GL_RGB, GL_FLOAT, pixeldata);
}

int main()
{

init();

createwindow(760, 360,"window", 0);
drawline(10,10, 380,180);
    while (!glfwWindowShouldClose(window))
        {
            render();
                glfwPollEvents();
                glfwSwapBuffers(window);
        }
glfwTerminate();
}

我的主编：

#ifndef MAIN_H_INCLUDED
#define MAIN_H_INCLUDED

//GL libs
#include <GL/glfw.h>
#include <GLM/glm.hpp>

// STD libs
#include <iostream>
#include <string>
#include <fstream>
#include <thread>
#include <cmath>

//shared functions

    //main.cpp
    void setpixel(unsigned int xloc, unsigned int yloc);
    //draw.cpp
    void drawline( unsigned int x0, unsigned int y0, unsigned int x1, unsigned int y1 );

我的draw.cpp：

#include "main.h"
//does not work, should draw a line
void drawline( unsigned int x0, unsigned int y0, unsigned int x1, unsigned int y1 )
{
int dx = x1 - x0;
int dy = y1 - y0;
int a = dy/dx;
int x2 = x0, y2 = y0;
int b = (a*x2) - y2;
    b *= -1;
    for (int i = x0; x0 <= x1; i++)
        {
            y2 = a*x2 + b;
            setpixel(i,y2);
        }


}

我忘了告诉，这是一个爱好项目。

Answer 1

看起来问题可能出在setpixel()：

void setpixel(unsigned int xloc,unsigned int yloc)
{
    unsigned int pixloc;
    pixloc = xloc * yloc; // <- this is wrong
    if(pixloc > size)
        {
            std::cout << "TOO FAR!";
            glfwWindowShouldClose(window);
            glfwTerminate();

        }
    else
        {
        pixeldata[pixloc*3] = 10; // <- and this is wrong
        }
}

第一个错误的行必须是：

pixloc = (yloc * bytesPerRow) + (xloc * bytesPerPixel);

在这种情况下，bytesPerRow为width * bytesPerPixel且bytesPerPixel为3

第二个错误的行可以是：

pixeldata [ pixloc ] = 10;

所有这一切，你不应该写自己的线描例程。您应该只使用OpenGL的线条绘制功能（GL_LINES）。

bresenham的线算法的实现让程序使用gldrawpixels（）崩溃，为什么？

1 个答案: