opengl创建天空盒实现反射和折射的效果

效果图

天空盒顶点shader

attribute vec3 pos;
attribute vec2 texcoord;
attribute vec3 normal;

uniform mat4 M;
uniform mat4 P;
uniform mat4 V;

varying vec3 V_Texcoord;
void main()
{
	V_Texcoord=pos;
	gl_Position=P*V*M*vec4(pos,1.0);
}

天空盒片元shader

varying vec3 V_Texcoord;
uniform samplerCube U_MainTexture;
void main()
{
	gl_FragColor=textureCube(U_MainTexture,V_Texcoord);
}

反射顶点shader

attribute vec3 pos;
attribute vec2 texcoord;
attribute vec3 normal;

uniform mat4 M;
uniform mat4 P;
uniform mat4 V;
uniform mat4 NM;

varying vec4 V_WorldPos;
varying vec3 V_Normal;

void main()
{
	V_WorldPos=M*vec4(pos,1.0);
	V_Normal=mat3(NM)*normal;//将法线坐标转换到世界空间
	gl_Position=P*V*M*vec4(pos,1.0);
}

反射片元shader

varying vec4 V_WorldPos;
varying vec3 V_Normal;
uniform samplerCube U_MainTexture;

void main()
{
	//视线方向向量
	vec3 eyeVec=normalize(V_WorldPos.xyz-vec3(0.0));
	vec3 n=normalize(V_Normal);
	//求视线方向的反射向量
	vec3 r=reflect(eyeVec,n);
	
	vec4 color=textureCube(U_MainTexture,r);

	gl_FragColor=color;
}

折射片元shader

varying vec4 V_WorldPos;
varying vec3 V_Normal;
uniform samplerCube U_MainTexture;

void main()
{
	vec3 eyeVec=normalize(V_WorldPos.xyz-vec3(0.0));
	vec3 n=normalize(V_Normal);
	vec3 r=refract(eyeVec,n,1.0/1.52);
	vec4 color=textureCube(U_MainTexture,r);

	gl_FragColor=color;
}

渲染函数

#include <windows.h>
#include "glew.h"
#include <stdio.h>
#include <math.h>
#include "utils.h"
#include "GPUProgram.h"
#include "ObjModel.h"
#include "FBO.h"
#include "FullScreenQuad.h"
#include "Glm/glm.hpp"
#include "Glm/ext.hpp"
#pragma comment(lib,"opengl32.lib")
#pragma comment(lib,"glew32.lib")



LRESULT CALLBACK GLWindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch (msg)
	{
	case WM_CLOSE:
		PostQuitMessage(0);
		break;
	}
	return DefWindowProc(hwnd,msg,wParam,lParam);
}


INT WINAPI WinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ LPSTR lpCmdLine, _In_ int nShowCmd)
{
	WNDCLASSEX wndClass;
	wndClass.cbClsExtra = 0;
	wndClass.cbSize = sizeof(WNDCLASSEX);
	wndClass.cbWndExtra = 0;
	wndClass.hbrBackground = NULL;
	wndClass.hCursor = LoadCursor(NULL,IDC_ARROW);
	wndClass.hIcon = NULL;
	wndClass.hIconSm = NULL;
	wndClass.hInstance = hInstance;
	wndClass.lpfnWndProc=GLWindowProc;
	wndClass.lpszClassName = L"OpenGL";
	wndClass.lpszMenuName = NULL;
	wndClass.style = CS_VREDRAW | CS_HREDRAW;
	ATOM atom = RegisterClassEx(&wndClass);

	RECT rect;
	rect.left = 0;
	rect.top = 0;
	rect.right = 1280;
	rect.bottom = 720;
	AdjustWindowRect(&rect, WS_OVERLAPPEDWINDOW, FALSE);
	HWND hwnd = CreateWindowEx(NULL, L"OpenGL", L"RenderWindow", WS_OVERLAPPEDWINDOW, 100, 100, rect.right-rect.left, rect.bottom-rect.top, NULL, NULL, hInstance, NULL);
	HDC dc = GetDC(hwnd);
	PIXELFORMATDESCRIPTOR pfd;
	memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));
	pfd.nVersion = 1;
	pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_TYPE_RGBA | PFD_DOUBLEBUFFER;
	pfd.iLayerType = PFD_MAIN_PLANE;
	pfd.iPixelType = PFD_TYPE_RGBA;
	pfd.cColorBits = 32;
	pfd.cDepthBits = 24;
	pfd.cStencilBits = 8;

	int pixelFormatID = ChoosePixelFormat(dc, &pfd);

	SetPixelFormat(dc,pixelFormatID,&pfd);

	HGLRC rc = wglCreateContext(dc);
	wglMakeCurrent(dc, rc);
	GetClientRect(hwnd, &rect);
	int viewportWidth = rect.right - rect.left, viewportHeight = rect.bottom - rect.top;
	glewInit();

	GPUProgram originalProgram;
	originalProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/skybox.vs");
	originalProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/skybox.fs");
	originalProgram.Link();
	originalProgram.DetectAttribute("pos");
	originalProgram.DetectAttribute("texcoord");
	originalProgram.DetectAttribute("normal");
	originalProgram.DetectUniform("M");
	originalProgram.DetectUniform("V");
	originalProgram.DetectUniform("P");
	originalProgram.DetectUniform("U_MainTexture");

	GPUProgram reflectionProgram;
	reflectionProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/reflection.vs");
	reflectionProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/reflection.fs");
	reflectionProgram.Link();
	reflectionProgram.DetectAttribute("pos");
	reflectionProgram.DetectAttribute("texcoord");
	reflectionProgram.DetectAttribute("normal");
	reflectionProgram.DetectUniform("M");
	reflectionProgram.DetectUniform("V");
	reflectionProgram.DetectUniform("P");
	reflectionProgram.DetectUniform("NM");
	reflectionProgram.DetectUniform("U_MainTexture");

	GPUProgram refractionProgram;
	refractionProgram.AttachShader(GL_VERTEX_SHADER, "Debug/res/shader/refraction.vs");
	refractionProgram.AttachShader(GL_FRAGMENT_SHADER, "Debug/res/shader/refraction.fs");
	refractionProgram.Link();
	refractionProgram.DetectAttribute("pos");
	refractionProgram.DetectAttribute("texcoord");
	refractionProgram.DetectAttribute("normal");
	refractionProgram.DetectUniform("M");
	refractionProgram.DetectUniform("V");
	refractionProgram.DetectUniform("P");
	refractionProgram.DetectUniform("NM");
	refractionProgram.DetectUniform("U_MainTexture");

	//init 3d model
	ObjModel cube,sphere;
	cube.Init("Debug/res/model/Cube.obj");
	sphere.Init("Debug/res/model/Sphere.obj");

	float identity[] = {
		1.0f,0,0,0,
		0,1.0f,0,0,
		0,0,1.0f,0,
		0,0,0,1.0f
	};

	glm::mat4 cubeModel;
	glm::mat4 sphereModel = glm::translate(-1.5f, 0.0f, -4.0f);
	glm::mat4 sphereNormalMatrix = glm::inverseTranspose(sphereModel);
	glm::mat4 sphereModel1 = glm::translate(1.5f, 0.0f, -4.0f);
	glm::mat4 sphereNormalMatrix1 = glm::inverseTranspose(sphereModel1);
	glm::mat4 cubeNormalMatrix = glm::inverseTranspose(cubeModel);

	glm::mat4 projectionMatrix = glm::perspective(50.0f, (float)viewportWidth / (float)viewportHeight, 0.1f, 1000.0f);

	glClearColor(0.6f, 0.6f, 0.6f, 1.0f);

	GLuint mainTexture = SOIL_load_OGL_cubemap(
		"Debug/res/image/right.png",
		"Debug/res/image/left.png", 
		"Debug/res/image/top.png", 
		"Debug/res/image/bottom.png", 
		"Debug/res/image/back.png", 
		"Debug/res/image/front.png",
		0, 0, SOIL_FLAG_POWER_OF_TWO);
	ShowWindow(hwnd, SW_SHOW);
	UpdateWindow(hwnd);

	MSG msg;
	while (true)
	{
		if (PeekMessage(&msg,NULL,NULL,NULL,PM_REMOVE))
		{
			if (msg.message==WM_QUIT)
			{
				break;
			}
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glDisable(GL_DEPTH_TEST);
		//normal rgba
		glUseProgram(originalProgram.mProgram);
		glUniformMatrix4fv(originalProgram.GetLocation("M"), 1, GL_FALSE, glm::value_ptr(cubeModel));
		glUniformMatrix4fv(originalProgram.GetLocation("V"), 1, GL_FALSE, identity);
		glUniformMatrix4fv(originalProgram.GetLocation("P"), 1, GL_FALSE, glm::value_ptr(projectionMatrix));

		//绘制天空盒
		glBindTexture(GL_TEXTURE_CUBE_MAP, mainTexture);
		glUniform1i(originalProgram.GetLocation("U_MainTexture"),0);
		cube.Bind(originalProgram.GetLocation("pos"), originalProgram.GetLocation("texcoord"), originalProgram.GetLocation("normal"));
		cube.Draw();
		glEnable(GL_DEPTH_TEST);
		//绘制反射球
		glUseProgram(reflectionProgram.mProgram);
		glUniformMatrix4fv(reflectionProgram.GetLocation("M"), 1, GL_FALSE, glm::value_ptr(sphereModel));
		glUniformMatrix4fv(reflectionProgram.GetLocation("V"), 1, GL_FALSE, identity);
		glUniformMatrix4fv(reflectionProgram.GetLocation("P"), 1, GL_FALSE, glm::value_ptr(projectionMatrix));
		glUniformMatrix4fv(reflectionProgram.GetLocation("NM"), 1, GL_FALSE, glm::value_ptr(sphereNormalMatrix));

		glBindTexture(GL_TEXTURE_CUBE_MAP, mainTexture);
		glUniform1i(reflectionProgram.GetLocation("U_MainTexture"), 0);
		sphere.Bind(reflectionProgram.GetLocation("pos"), reflectionProgram.GetLocation("texcoord"), reflectionProgram.GetLocation("normal"));
		sphere.Draw();

		//绘制折射球
		glUseProgram(refractionProgram.mProgram);
		glUniformMatrix4fv(refractionProgram.GetLocation("M"), 1, GL_FALSE, glm::value_ptr(sphereModel1));
		glUniformMatrix4fv(refractionProgram.GetLocation("V"), 1, GL_FALSE, identity);
		glUniformMatrix4fv(refractionProgram.GetLocation("P"), 1, GL_FALSE, glm::value_ptr(projectionMatrix));
		glUniformMatrix4fv(refractionProgram.GetLocation("NM"), 1, GL_FALSE, glm::value_ptr(sphereNormalMatrix1));

		glBindTexture(GL_TEXTURE_CUBE_MAP, mainTexture);
		glUniform1i(refractionProgram.GetLocation("U_MainTexture"), 0);
		sphere.Bind(refractionProgram.GetLocation("pos"), refractionProgram.GetLocation("texcoord"), refractionProgram.GetLocation("normal"));
		sphere.Draw();

		glFlush();
		SwapBuffers(dc);
	}
	return 0;
}