CryEngine5.5 用代码“画”一个模型

浅浅的花香味﹌ 2023-10-17 23:36 1阅读 0赞

基本搞图形的都学过点OpenGL,或者OSG。在OpenGL或者OSG里面要绘制一个模型基本上是自己通过代码来绘制，自己定义一些顶点、索引、法线、颜色等信息然后make一个Node,把Node加入场景图中才能渲染出一个模型（基本引擎都是这个步骤）。但是在CE或者UE中这种方法很没人提起，因为游戏引擎基本所有模型都从外部导入，很少需要自己从代码开始写，如果想把这部分研究透彻建议去看CE是怎么加载CGF模型的，我也有相关的博客粗浅说了一下。因为我有特殊的需求，模型需要用代码逻辑控制，所以必须自己从代码开始实现一个模型。  
本人很不会写文章，就直接上代码，由于材质前期没有搞上但是现在弄上了来补充下。

![在这里插入图片描述][70]

### 代码分类 ###

> 1.头文件  
> 2.源文件  
> 3.调用方式

#### 头文件(MakeModel.h) ####

#pragma once
    
    #include <vector>
    
    struct IStatObj;
    
    struct Edge;
    
    struct Vertex
    {
    	Vec3 pos;
    	Vec2 projected;
    	Vec3 smoothedNormal;
    };
    
    struct VertexNormal
    {
    	VertexNormal() : normal(ZERO), weighting(0.0f) {}
    	Vec3 normal;
    	float weighting;
    };
    
    struct Face
    {
    	Vertex *v[3];
    	Edge* edges[3];
    	float a[3];
    	bool bDone;
    };
    
    struct Edge
    {
    	Vertex *v[2];
    	Face *faces[2];
    };
    
    struct Tri
    {
    	Tri(Vec2 &a, Vec2 &b, Vec2 &c, Vec3 &ap, Vec3 &bp, Vec3 &cp, Vertex *va, Vertex *vb, Vertex *vc)
    	{
    		v[0] = a;
    		v[1] = b;
    		v[2] = c;
    		pos[0] = ap;
    		pos[1] = bp;
    		pos[2] = cp;
    		orig[0] = va;
    		orig[1] = vb;
    		orig[2] = vc;
    	}
    	Vec2 v[3];
    	Vec3 pos[3];
    	Vec3 tangent;
    	Vec3 bitangent;
    	Vec3 normal;
    	Vertex *orig[3];
    };
    
    typedef struct FinalVertex
    {
    	Vec3 pos;
    	Vec2 uv;
    	Vec3 tangent;
    	Vec3 bitangent;
    	Vec3 normal;
    	Vertex *orig;
    } FinalVertex;
    
    namespace HelperUtil
    {
    
    	struct MakeModel
    	{
    		static IStatObj* MakeMesh(std::vector<FinalVertex> &vertices, std::vector<int> &indices);
    		static void CalcTBN(std::vector<FinalVertex> &vertices, std::vector<int> &indices);
    	};
    
    };

#### 源文件(MakeModel.cpp) ####

#include "StdAfx.h"
    #include "MakeModel.h"
    
    #include<Cry3DEngine/IIndexedMesh.h>
    
    using namespace HelperUtil;
    
    
    IStatObj * MakeModel::MakeMesh(std::vector<FinalVertex>& vertices, std::vector<int>& indices)
    {
    	//计算TBN坐标
    	HelperUtil::MakeModel::CalcTBN(vertices, indices);
    
    	CMesh *outMesh = new CMesh();
    	outMesh->SetIndexCount(indices.size());
    	outMesh->SetVertexCount(vertices.size());
    	outMesh->ReallocStream(CMesh::TEXCOORDS, vertices.size());
    	outMesh->ReallocStream(CMesh::NORMALS, vertices.size());
    	outMesh->ReallocStream(CMesh::TANGENTS, vertices.size());
    	outMesh->ReallocStream(CMesh::COLORS_0, vertices.size());
    	outMesh->ReallocStream(CMesh::COLORS_1, vertices.size());
    
    	AABB bb(AABB::RESET);
    
    	Vec3* pVertices0 = outMesh->GetStreamPtr<Vec3>(CMesh::POSITIONS);
    	SMeshNormal* pNormals = outMesh->GetStreamPtr<SMeshNormal>(CMesh::NORMALS);
    	SMeshTexCoord* pTexCoords0 = outMesh->GetStreamPtr<SMeshTexCoord>(CMesh::TEXCOORDS);
    	SMeshTangents* pTangents0 = outMesh->GetStreamPtr<SMeshTangents>(CMesh::TANGENTS);
    	SMeshColor* pColor0 = outMesh->GetStreamPtr<SMeshColor>(CMesh::COLORS_0);
    	SMeshColor* pColor1 = outMesh->GetStreamPtr<SMeshColor>(CMesh::COLORS_1);
    
    	for (std::vector<FinalVertex>::iterator vit = vertices.begin(), vend = vertices.end(); vit != vend; ++vit)
    	{
    		bb.Add(vit->pos);
    
    		*pVertices0++ = vit->pos;
    		*pTexCoords0++ = SMeshTexCoord(vit->uv.x, vit->uv.y);
    		*pTangents0++ = SMeshTangents(vit->tangent, vit->bitangent,vit->normal);
    		*pNormals++ = SMeshNormal(vit->normal);
    		*pColor0++ = SMeshColor(155, 0, 140, 255);
    		*pColor1++ = SMeshColor(155, 0, 140, 255);
    	}
    
    	vtx_idx* pIndices0 = outMesh->GetStreamPtr<vtx_idx>(CMesh::INDICES);
    	vtx_idx* pIndices = pIndices0;
    	for (std::vector<int>::iterator it = indices.begin(), end = indices.end(); it != end; ++it)
    	{
    		*(pIndices++) = (vtx_idx)*it;
    	}
    
    	//area
    	float area = 0.0f;
    	float tarea = 0.0f;
    	for (int i = 0; i<indices.size(); i += 3)
    	{
    		int idx0 = pIndices0[i + 0];
    		int idx1 = pIndices0[i + 1];
    		int idx2 = pIndices0[i + 2];
    		Vec3 e0 = pVertices0[idx1] - pVertices0[idx0];
    		Vec3 e1 = pVertices0[idx2] - pVertices0[idx0];
    		Vec2 t0 = pTexCoords0[idx0].GetUV();
    		Vec2 t1 = pTexCoords0[idx1].GetUV();
    		Vec2 t2 = pTexCoords0[idx2].GetUV();
    		Vec2 ta = Vec2(t1.x - t0.x, t1.y - t0.y);
    		Vec2 tb = Vec2(t2.x - t0.x, t2.y - t0.y);
    		area += e0.Cross(e1).len();
    		tarea += ta.Cross(tb);
    	}
    
    	SMeshSubset subset;
    	subset.nFirstIndexId = 0;
    	subset.nNumIndices = indices.size();
    	subset.nFirstVertId = 0;
    	subset.nNumVerts = vertices.size();
    	subset.nMatID = 0;
    	subset.nMatFlags = 0;
    	subset.fRadius = 100.0f;
    	if (area != 0.0f)
    		subset.fTexelDensity = tarea / area;
    	else
    		subset.fTexelDensity = 1.0f;
    
    
    	outMesh->m_subsets.push_back(subset);
    
    	IStatObj *pOutStatObj = gEnv->p3DEngine->CreateStatObjOptionalIndexedMesh(false);
    	IIndexedMesh *pIdxMesh = pOutStatObj->GetIndexedMesh(false);
    	if (!pIdxMesh)
    		pIdxMesh = pOutStatObj->CreateIndexedMesh();
    	pIdxMesh->SetMesh(*outMesh);
    	delete outMesh;
    	pOutStatObj->SetBBoxMin(bb.min);
    	pOutStatObj->SetBBoxMax(bb.max);
    	pOutStatObj->Invalidate();
    	return pOutStatObj;
    }
    
    void HelperUtil::MakeModel::CalcTBN(std::vector<FinalVertex>& vertices, std::vector<int>& indices)
    {
    	for (int i = 0; i < indices.size(); i += 3)
    	{
    		int idx0 = indices[i + 0];
    		int idx1 = indices[i + 1];
    		int idx2 = indices[i + 2];
    
    		Vec3 v0 = vertices.at(idx0).pos;
    		Vec3 v1 = vertices.at(idx1).pos;
    		Vec3 v2 = vertices.at(idx2).pos;
    
    		Vec2 t0 = vertices.at(idx0).uv;
    		Vec2 t1 = vertices.at(idx1).uv;
    		Vec2 t2 = vertices.at(idx2).uv;
    
    		Vec3 n0 = (Vec3(v0.x, t0.x, t0.y) - Vec3(v1.x, t1.x, t1.y)).cross(Vec3(v0.x, t0.x, t0.y) - Vec3(v2.x, t2.x, t2.y));
    		Vec3 n1 = (Vec3(v0.y, t0.x, t0.y) - Vec3(v1.y, t1.x, t1.y)).cross(Vec3(v0.y, t0.x, t0.y) - Vec3(v2.y, t2.x, t2.y));
    		Vec3 n2 = (Vec3(v0.z, t0.x, t0.y) - Vec3(v1.z, t1.x, t1.y)).cross(Vec3(v0.z, t0.x, t0.y) - Vec3(v2.z, t2.x, t2.y));
    
    		float Tx = -n0.y / n0.x;
    		float Ty = -n1.y / n1.x;
    		float Tz = -n2.y / n2.x;
    		Vec3 T = Vec3(Tx, Ty, Tz);
    
    		float Bx = -n0.z / n0.x;
    		float By = -n1.z / n1.x;
    		float Bz = -n2.z / n2.x;
    		Vec3 B = Vec3(Bx, By, Bz);
    
    		Vec3 N = T.cross(B);
    
    		vertices.at(idx0).tangent = T;
    		vertices.at(idx1).tangent = T;
    		vertices.at(idx2).tangent = T;
    
    		vertices.at(idx0).bitangent = B;
    		vertices.at(idx1).bitangent = B;
    		vertices.at(idx2).bitangent = B;
    
    		vertices.at(idx0).normal = N;
    		vertices.at(idx1).normal = N;
    		vertices.at(idx2).normal = N;
    	}
    }

#### 调用方式 ####

void CPlayerComponent::DrawModel()
    {
    	/*模型所在位置*/
    	const float heightOffset = 10.f;
    	float terrainCenter = gEnv->p3DEngine->GetTerrainSize() / 2.f;
    	float height = gEnv->p3DEngine->GetTerrainZ(terrainCenter, terrainCenter);
    	Vec3 playerPosition = Vec3(terrainCenter, terrainCenter, height + heightOffset);
    
    	IRenderNode* pRenderNode = gEnv->p3DEngine->CreateRenderNode(EERType::eERType_Brush);
    	/*从顶点创建Mesh*/
    	std::vector<FinalVertex> vertices;
    	for (size_t i = 0; i < 3; ++i)
    	{
    		FinalVertex vertex;
    		vertex.pos = ZERO;
    		vertex.uv = ZERO;
    		vertex.tangent = ZERO;
    		vertex.bitangent = ZERO;
    		vertex.orig = nullptr;
    
    		vertices.push_back(vertex);
    	}
    	vertices.at(0).pos = Vec3(-1, 0, -1);
    	vertices.at(0).uv = Vec2(0.0, 0.0);
    
    	vertices.at(1).pos = Vec3(1, 0, -1);
    	vertices.at(1).uv = Vec2(1.0, 0.0);
    
    	vertices.at(2).pos = Vec3(1, 0, 1);
    	vertices.at(2).uv = Vec2(1.0, 1.0);
    
    	std::vector<int> indices{ 0,1,2 };
    
    	IStatObj*   pStatObj = HelperUtil::MakeModel::MakeMesh(vertices, indices);
    
    	IMaterial* pMaterial = gEnv->p3DEngine->GetMaterialManager()->LoadMaterial("G:\\CryEngine\\CEProject\\test\\Assets\\Materials\\generic\\metal\\gold.mtl");
    	pStatObj->SetMaterial(pMaterial);
    
    	Matrix34 mat;
    	mat.SetIdentity();
    	mat.SetTranslation(playerPosition);
    	pRenderNode->SetEntityStatObj(pStatObj, &mat);
    
    	gEnv->p3DEngine->RegisterEntity(pRenderNode);
    }

模型的绘制只需要UV、顶点坐标、索引数组就行了，TBN信息可以根据以上三个数据信息通过算法生成。

[70]: https://img-blog.csdn.net/20181010141141298?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzE2MTIzMjc5/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70