系列三：OPENGL我来了

Posted 2021-02-28 unicornsir

完成系列二后，心里相当激动，如果能看到精美的游戏动画多好......

这不是做梦，有梦想就能实现，但是我们还是一步一步来，先来看一下显示普通的图形

注：在此版本里，用了最容易的老式OPENGL，后面接下来用的是新式的moden opengl

 

MainGame.h

 1 #pragma once
 2 #include <SDL/SDL.h>
 3 #include <GL/glew.h>
 4 
 5 enum class GameState{PLAY, EXIT};
 6 
 7 class MainGame
 8 {
 9 public:
10     MainGame();
11     ~MainGame();
12 
13     void run();
14     
15 
16 private:
17     void initSystems();
18     void gameLoop();
19     void processInput();
20     void drawGame();
21 
22     SDL_Window* m_pWindow;
23     int m_nScreenWidth;
24     int m_nScreenHeight;
25     GameState m_gameState;
26 };

View Code

 

MainGame.cpp

 1 #include "MainGame.h"
 2 #include <iostream>
 3 #include <string>
 4 void faterError(const std::string& errorString)
 5 {
 6     std::cout << errorString << std::endl;
 7     std::cout << "Enter any key to quit...";
 8     std::cin.get();
 9     SDL_Quit();
10 }
11 
12 MainGame::MainGame() :m_pWindow(nullptr), m_nScreenWidth(1024), m_nScreenHeight(768), m_gameState(GameState::PLAY)
13 {
14 
15 }
16 
17 
18 MainGame::~MainGame()
19 {
20 }
21 
22 void MainGame::run()
23 {
24     initSystems();
25 
26     gameLoop();
27 }
28 
29 void MainGame::initSystems()
30 {
31     //Initialize SDL
32     SDL_Init(SDL_INIT_EVERYTHING);
33     m_pWindow = SDL_CreateWindow("GraphicToturial", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, m_nScreenWidth, m_nScreenHeight, SDL_WINDOW_OPENGL);
34     if (nullptr == m_pWindow)
35     {
36         faterError("SDL Window could not be created!");
37     }
38 
39     SDL_GLContext glContext = SDL_GL_CreateContext(m_pWindow);
40     if (nullptr == glContext)
41     {
42         faterError("SDL_GL context could not be created!");
43     }
44 
45     GLenum result = glewInit();
46     if (GLEW_OK != result)
47     {
48         faterError("Could not initialize glew!");
49     }
50 
51     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
52 
53     glClearColor(0, 0, 1, 1);
54 }
55 
56 void MainGame::gameLoop()
57 {
58     while (m_gameState != GameState::EXIT)
59     {
60         processInput();
61         drawGame();
62     }
63 }
64 
65 void MainGame::processInput()
66 {
67     SDL_Event evnt;
68     while (SDL_PollEvent(&evnt))
69     {
70         switch (evnt.type)
71         {
72         case SDL_QUIT:
73             m_gameState = GameState::EXIT;
74             break;
75         case SDL_MOUSEMOTION:
76             std::cout << evnt.motion.x << " " << evnt.motion.y << std::endl;
77             break;
78         }
79     }
80 }
81 
82 void MainGame::drawGame()
83 {
84     glClearDepth(1.0);
85     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
86 
87     glEnableClientState(GL_COLOR_ARRAY);
88     glColor3f(1.0f, 0.0f, 0.0f);
89     glBegin(GL_TRIANGLES);
90     glVertex2f(0.0f, 0.0f);
91     glVertex2f(0.0f, 500.0f);
92     glVertex2f(500.f, 500.0f);
93     glEnd();
94 
95     SDL_GL_SwapWindow(m_pWindow);
96 }

View Code