OpenGL program

Development Platform:
Visual C++

main.cpp：Code Content
							#include <stdio.h>
#include <conio.h>
#include "Gut.h"
#include "GutInput.h"
#include "GutTimer.h"
#include "render_dx9.h"
#include "render_opengl.h"
#include "render_data.h"
#ifdef _ENABLE_DX10_
#include "render_dx10.h"
#endif
GutTimer g_Timer;
void GetUserInput(void)
{
	// `读取鼠标`
	GutMouseInfo mouse;
	GutReadMouse(&mouse);
	// `读取键盘`
	char keyboard_state[256];
	GutReadKeyboard(keyboard_state);
	// `获得画完前一个画面到现在所经历的时间`
	float time_diff = g_Timer.Stop();
	g_Timer.Restart();
	float moving_speed = 2.0f * time_diff;
	float rotation_speed = 1.0 * time_diff;
	// `极坐标系统`
	static float theta = -MATH_PI * 0.5f;
	static float phi = 0.0f;
	// `如果左击, 就旋转镜头.`
	if ( mouse.button[0] ) 
	{
		theta += mouse.x * rotation_speed;
		phi -= mouse.y * rotation_speed;
	}
	float sin_phi, cos_phi;
	float sin_theta, cos_theta;
	
	FastMath::SinCos(phi, sin_phi, cos_phi);
	FastMath::SinCos(theta, sin_theta, cos_theta);
	// `计算镜头的法线`
	Vector4 camera_facing;
	camera_facing[0] = cos_phi * cos_theta;
	camera_facing[1] = sin_phi;
	camera_facing[2] = cos_phi * sin_theta;
	// `计算镜头正上方的轴向`
	Vector4 camera_up;
	FastMath::SinCos(phi + MATH_PI*0.5f, sin_phi, cos_phi);
	camera_up[0] = cos_phi * cos_theta;
	camera_up[1] = sin_phi;
	camera_up[2] = cos_phi * sin_theta;
	// `获得镜面右方的方向`
	Vector4 camera_right = Vector3CrossProduct(camera_facing, camera_up);
	// `按下W或方向键向上`
	if ( keyboard_state[GUTKEY_W] || keyboard_state[GUTKEY_UP] )
	{
		g_eye += camera_facing * moving_speed;
	}
	// `按下S或方向键向下`
	if ( keyboard_state[GUTKEY_S] || keyboard_state[GUTKEY_DOWN] )
	{
		g_eye -= camera_facing * moving_speed;
	}
	// `按下A或方向键向左`
	if ( keyboard_state[GUTKEY_A] || keyboard_state[GUTKEY_LEFT] )
	{
		g_eye -= camera_right * moving_speed;
	}
	// `按下D或方向键向右`
	if ( keyboard_state[GUTKEY_D] || keyboard_state[GUTKEY_RIGHT] )
	{
		g_eye += camera_right * moving_speed;
	}
	// `计算出镜头对准的点, 生成镜头转换矩阵时会用到.`
	g_lookat = g_eye + camera_facing;
	// `因为是对2个轴转动, 需要更新镜头朝上的轴.`
	g_up = camera_up;
}
void main(int argc, char *argv[])
{
	// 默认使用DirectX 9来绘图
	char *device = "dx9";
	void (*render)(void) = RenderFrameDX9;
	bool (*init_resource)(void) = InitResourceDX9;
	bool (*release_resource)(void) = ReleaseResourceDX9;
#ifdef _ENABLE_DX10_
	printf("Pressn(1) for Direct3D9n(2) for OpenGLn(3) for Direct3D10n");
#else
	printf("Pressn(1) for Direct3D9n(2) for OpenGLn");
#endif
	int c = getche();
	switch(c)
	{
	default:
	case '1':
		render = RenderFrameDX9;
		init_resource = InitResourceDX9;
		release_resource = ReleaseResourceDX9;
		break;
	case '2':
		device = "opengl";
		init_resource = InitResourceOpenGL;
		release_resource = ReleaseResourceOpenGL;
		render = RenderFrameOpenGL;
		break;
	case '3':
	#ifdef _ENABLE_DX10_
		device = "dx10";
		init_resource = InitResourceDX10;
		release_resource = ReleaseResourceDX10;
		render = RenderFrameDX10;
	#endif
		break;
	}
	// 在(100,100)的位置打开一个大小为(512x512)的窗口
	GutCreateWindow(100, 100, 512, 512, device);
	// 做OpenGL或DirectX初始化
	if ( !GutInitGraphicsDevice(device) )
	{
		printf("Failed to initialize %s devicen", device);
		exit(0);
	}
	GutInputInit();
	g_view_matrix.Identity();
	// 载入shader
	if ( !init_resource() )
	{
		release_resource();
		printf("Failed to load resourcesn");
		exit(0);
	}
	// 主循环
	while( GutProcessMessage() )
	{
		GetUserInput();
		render();
	}
	
	// 释放shader
	release_resource();
	// 关闭OpenGL/DirectX绘图装备
	GutReleaseGraphicsDevice();
}

						