图形学基础概念(画布/位图/像素等)

这里写目录标题

  • 1 介绍
  • 2 基本概念
  • 3 基础demo框架搭建
    • 3.1 win32窗口原理
    • 3.2 搭建demo框架
  • 4 点/直线/雪花效果

1 介绍

看过那些书,走过那些路,依然过不好这一生;用过很多框架,依然成不了好的架构师。
本系列主要是介绍如果只给你一个点,让你实现一个3D的实现的过程以及会涉及到那些图形学知识。

2 基本概念

像素: RGBA四元素组成 (每个元素都是1byte,8个bit位)
含义:R红色 G绿色 B蓝色 A透明度
四元素计算出来就是像素点的颜色
画布:屏幕
位图:很多像素点组成
HDC:

3 基础demo框架搭建

3.1 win32窗口原理

1.编写WinMain函数

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)

2.设计窗口类(WNDCLASS)

    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_WINDOWSPROJECT1, szWindowClass, MAX_LOADSTRING);

3.注册窗口类(RegisterClass)

ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINDOWSPROJECT1));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

4.创建窗口(CreatWindow)

    hWnd = CreateWindowW(szWindowClass, szTitle, WS_POPUP,
      CW_USEDEFAULT, 0, wWidth, wHeight, nullptr, nullptr, hInstance, nullptr);

5.显示并更新窗口

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

6.编写消息循环

    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

7.编写窗口过程函数

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // 分析菜单选择:
            switch (wmId)
            {
            case IDM_ABOUT:
                DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                break;
            case IDM_EXIT:
                DestroyWindow(hWnd);
                break;
            default:
                return DefWindowProc(hWnd, message, wParam, lParam);
            }
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // TODO: 在此处添加使用 hdc 的任何绘图代码...
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

3.2 搭建demo框架

//基础坐标

#pragma once

namespace GT
{
	template<typename T>
	struct tVec2
	{
		T x;
		T y;

		tVec2(T _x, T _y)
		{
			x = _x;
			y = _y;
		}

		tVec2()
		{
			x = -1;
			y = -1;
		}
	};

	typedef tVec2<int>		intV2;
	typedef tVec2<float>	floatV2;

	typedef unsigned int	uint;
	typedef unsigned char   byte;
}

//像素描述

#pragma once
#include 
#include "GTMATH.hpp"

namespace GT
{
	struct RGBA  //像素
	{
		byte m_r;
		byte m_g;
		byte m_b;
		byte m_a;

		RGBA(byte _r = 255, 
			 byte _g = 255,
			 byte _b = 255,
			 byte _a = 255)
		{
			m_r = _r;
			m_g = _g;
			m_b = _b;
			m_a = _a;
		}

	};
//画布
	class Canvas
	{
	private:
		int m_width;
		int m_height;
		RGBA* m_buffer;

	public:
		Canvas(int _width, int _height, void* _buffer)
		{
			if (_width <= 0 || _height <= 0)
			{
				m_width = -1;
				m_height = -1;
				m_buffer = nullptr;
			}

			m_width = _width;
			m_height = _height;
			m_buffer = (RGBA*)_buffer;
		}

		~Canvas()
		{

		}
		// 清洗操作类似opengl gl_clear
		void clear()
		{
			if (m_buffer != nullptr)
			{
				memset(m_buffer, 0, sizeof(RGBA) * m_width * m_height);
			}
		}

		//画点操作
		void drawPoint(int x, int y, RGBA _color)
		{
			// 屏幕外,不画
			if (x < 0 || x >= m_width || y < 0 || y >= m_height)
			{
				return;
			}

			m_buffer[y * m_width + x] = _color;


		}

	};
}

//main函数

// WindowsProject1.cpp : 定义应用程序的入口点。
//

#include "framework.h"
#include "WindowsProject1.h"
#include "Canvas.h"

#define MAX_LOADSTRING 100

// 全局变量:
HINSTANCE hInst;                                // 当前实例
WCHAR szTitle[MAX_LOADSTRING];                  // 标题栏文本
WCHAR szWindowClass[MAX_LOADSTRING];            // 主窗口类名
HWND hWnd;
int wWidth = 800;
int wHeight = 600;
HDC hDC = NULL;
HDC hMem = NULL;

GT::Canvas* _canvas = NULL;


// 此代码模块中包含的函数的前向声明:
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);
void Render();

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_WINDOWSPROJECT1, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // 执行应用程序初始化:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_WINDOWSPROJECT1));

    //*******************创建绘图用的位图********************
    void* buffer = 0;

    hDC = GetDC(hWnd);
    hMem = ::CreateCompatibleDC(hDC);

    BITMAPINFO bmpInfo;
    bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bmpInfo.bmiHeader.biWidth = wWidth;
    bmpInfo.bmiHeader.biHeight = wHeight;
    bmpInfo.bmiHeader.biPlanes = 1;
    bmpInfo.bmiHeader.biBitCount = 32;
    bmpInfo.bmiHeader.biCompression = BI_RGB;   //实际上存储的RGB
    bmpInfo.bmiHeader.biSizeImage = 0;
    bmpInfo.bmiHeader.biXPelsPerMeter = 0;
    bmpInfo.bmiHeader.biYPelsPerMeter = 0;
    bmpInfo.bmiHeader.biClrUsed = 0;
    bmpInfo.bmiHeader.biClrImportant = 0;

    HBITMAP hBmp = CreateDIBSection(hDC, &bmpInfo, DIB_RGB_COLORS, (void**)&buffer, 0, 0); //在这里创建Buffer内存
    SelectObject(hMem, hBmp);

    memset(buffer, 0, wWidth * wHeight * 4);  //清空buffer为0
     //*******************创建绘图用的位图********************

    _canvas = new GT::Canvas(wWidth, wHeight, buffer);

    MSG msg;

    // 主消息循环:
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }

        Render();
    }

    return (int) msg.wParam;
}


void Render()
{
    _canvas->clear();

    GT::RGBA _color(255, 0, 0, 0);
    //点  为何是蓝色
    _canvas->drawPoint(rand() % wWidth, rand() % wHeight, _color);

    //直线 
    for (int x = 0; x < wWidth; x++)
    {
        _canvas->drawPoint(x, 100, _color);
    }

    //雪花
    //for (int x = 0; x < wWidth; x++)
    //{
    //    for (int y = 0; y < wHeight; y++)
    //    {
    //        GT::RGBA _color(rand() % 255, rand() % 255, rand() % 255);
    //        _canvas->drawPoint(x, y, _color);
    //    }
    //    
    //}

    //在这里画到设备上,hMem相当于缓冲区(将缓冲区buffer画到hdc上)
    BitBlt(hDC, 0, 0, wWidth, wHeight, hMem, 0, 0, SRCCOPY);
}

//
//  函数: MyRegisterClass()
//
//  目标: 注册窗口类。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WINDOWSPROJECT1));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName   = NULL;
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   函数: InitInstance(HINSTANCE, int)
//
//   目标: 保存实例句柄并创建主窗口
//
//   注释:
//
//        在此函数中,我们在全局变量中保存实例句柄并
//        创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   hInst = hInstance; // 将实例句柄存储在全局变量中

    hWnd = CreateWindowW(szWindowClass, szTitle, WS_POPUP,
      CW_USEDEFAULT, 0, wWidth, wHeight, nullptr, nullptr, hInstance, nullptr);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  目标: 处理主窗口的消息。
//
//  WM_COMMAND  - 处理应用程序菜单
//  WM_PAINT    - 绘制主窗口
//  WM_DESTROY  - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // 分析菜单选择:
            switch (wmId)
            {
            case IDM_ABOUT:
                DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                break;
            case IDM_EXIT:
                DestroyWindow(hWnd);
                break;
            default:
                return DefWindowProc(hWnd, message, wParam, lParam);
            }
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // TODO: 在此处添加使用 hdc 的任何绘图代码...
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
        {
            EndDialog(hDlg, LOWORD(wParam));
            return (INT_PTR)TRUE;
        }
        break;
    }
    return (INT_PTR)FALSE;
}

4 点/直线/雪花效果

    GT::RGBA _color(255, 0, 0, 0);
    //点  为何是蓝色
    _canvas->drawPoint(rand() % wWidth, rand() % wHeight, _color);

    //直线 
    for (int x = 0; x < wWidth; x++)
    {
        _canvas->drawPoint(x, 100, _color);
    }

    //雪花
    //for (int x = 0; x < wWidth; x++)
    //{
    //    for (int y = 0; y < wHeight; y++)
    //    {
    //        GT::RGBA _color(rand() % 255, rand() % 255, rand() % 255);
    //        _canvas->drawPoint(x, y, _color);
    //    }
    //    
    //}

线是很多点绘制而成

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