我从我的老师那里得到了一个代码，目前显示了一个 3D 地球和一个 2D 粒子系统。摄像机绕圈移动。粒子系统应该面向相机。
根据我的讲义，我必须将广告牌乘以相机 View 矩阵的逆矩阵。我很想尝试一下，但是我在使用 View 矩阵的变量时遇到了问题。
#include "pch.h"
#include <Kore/Application.h>
#include <Kore/IO/FileReader.h>
#include <Kore/Math/Core.h>
#include <Kore/Math/Random.h>
#include <Kore/System.h>
#include <Kore/Input/Keyboard.h>
#include <Kore/Input/Mouse.h>
#include <Kore/Audio/Mixer.h>
#include <Kore/Graphics/Image.h>
#include <Kore/Graphics/Graphics.h>
#include <Kore/Log.h>
#include "ObjLoader.h"
#include "Collision.h"
#include "PhysicsWorld.h"
#include "PhysicsObject.h"
using namespace Kore;
// A simple particle implementation
class Particle {
public:
VertexBuffer* vb;
IndexBuffer* ib;
mat4 M;
// The current position
vec3 position;
// The current velocity
vec3 velocity;
// The remaining time to live
float timeToLive;
// The total time time to live
float totalTimeToLive;
// Is the particle dead (= ready to be re-spawned?)
bool dead;
void init(const VertexStructure& structure) {
vb = new VertexBuffer(4, structure,0);
float* vertices = vb->lock();
SetVertex(vertices, 0, -1, -1, 0, 0, 0);
SetVertex(vertices, 1, -1, 1, 0, 0, 1);
SetVertex(vertices, 2, 1, 1, 0, 1, 1);
SetVertex(vertices, 3, 1, -1, 0, 1, 0);
vb->unlock();
// Set index buffer
ib = new IndexBuffer(6);
int* indices = ib->lock();
indices[0] = 0;
indices[1] = 1;
indices[2] = 2;
indices[3] = 0;
indices[4] = 2;
indices[5] = 3;
ib->unlock();
dead = true;
}
void Emit(vec3 pos, vec3 velocity, float timeToLive) {
position = pos;
this->velocity = velocity;
dead = false;
this->timeToLive = timeToLive;
totalTimeToLive = timeToLive;
}
Particle() {
}
void SetVertex(float* vertices, int index, float x, float y, float z, float u, float v) {
vertices[index* 8 + 0] = x;
vertices[index*8 + 1] = y;
vertices[index*8 + 2] = z;
vertices[index*8 + 3] = u;
vertices[index*8 + 4] = v;
vertices[index*8 + 5] = 0.0f;
vertices[index*8 + 6] = 0.0f;
vertices[index*8 + 7] = -1.0f;
}
void render(TextureUnit tex, Texture* image) {
Graphics::setTexture(tex, image);
Graphics::setVertexBuffer(*vb);
Graphics::setIndexBuffer(*ib);
Graphics::drawIndexedVertices();
}
void Integrate(float deltaTime) {
timeToLive -= deltaTime;
if (timeToLive < 0.0f) {
dead = true;
}
// Note: We are using no forces or gravity at the moment.
position += velocity * deltaTime;
// Build the matrix
M = mat4::Translation(position.x(), position.y(), position.z()) * mat4::Scale(0.2f, 0.2f, 0.2f);
}
};
class ParticleSystem {
public:
// The center of the particle system
vec3 position;
// The minimum coordinates of the emitter box
vec3 emitMin;
// The maximal coordinates of the emitter box
vec3 emitMax;
// The list of particles
Particle* particles;
// The number of particles
int numParticles;
// The spawn rate
float spawnRate;
// When should the next particle be spawned?
float nextSpawn;
ParticleSystem(int maxParticles, const VertexStructure& structure ) {
particles = new Particle[maxParticles];
numParticles = maxParticles;
for (int i = 0; i < maxParticles; i++) {
particles[i].init(structure);
}
spawnRate = 0.05f;
nextSpawn = spawnRate;
position = vec3(0.5f, 1.3f, 0.5f);
float b = 0.1f;
emitMin = position + vec3(-b, -b, -b);
emitMax = position + vec3(b, b, b);
}
void update(float deltaTime) {
// Do we need to spawn a particle?
nextSpawn -= deltaTime;
bool spawnParticle = false;
if (nextSpawn < 0) {
spawnParticle = true;
nextSpawn = spawnRate;
}
for (int i = 0; i < numParticles; i++) {
if (particles[i].dead) {
if (spawnParticle) {
EmitParticle(i);
spawnParticle = false;
}
}
particles[i].Integrate(deltaTime);
}
}
void render(TextureUnit tex, Texture* image, ConstantLocation mLocation, mat4 V) {
Graphics::setBlendingMode(BlendingOperation::SourceAlpha, BlendingOperation::InverseSourceAlpha);
Graphics::setRenderState(RenderState::DepthWrite, false);
/************************************************************************/
/* Exercise 7 1.1 */
/************************************************************************/
/* Change the matrix V in such a way that the billboards are oriented towards the camera */
/************************************************************************/
/* Exercise 7 1.2 */
/************************************************************************/
/* Animate using at least one new control parameter */
for (int i = 0; i < numParticles; i++) {
// Skip dead particles
if (particles[i].dead) continue;
Graphics::setMatrix(mLocation, particles[i].M * V);
particles[i].render(tex, image);
}
Graphics::setRenderState(RenderState::DepthWrite, true);
}
float getRandom(float minValue, float maxValue) {
int randMax = 1000000;
int randInt = Random::get(0, randMax);
float r = (float) randInt / (float) randMax;
return minValue + r * (maxValue - minValue);
}
void EmitParticle(int index) {
// Calculate a random position inside the box
float x = getRandom(emitMin.x(), emitMax.x());
float y = getRandom(emitMin.y(), emitMax.y());
float z = getRandom(emitMin.z(), emitMax.z());
vec3 pos;
pos.set(x, y, z);
vec3 velocity(0, 0.3f, 0);
particles[index].Emit(pos, velocity, 3.0f);
}
};
namespace {
const int width = 1024;
const int height = 768;
double startTime;
Shader* vertexShader;
Shader* fragmentShader;
Program* program;
float angle = 0.0f;
// null terminated array of MeshObject pointers
MeshObject* objects[] = { nullptr, nullptr, nullptr, nullptr, nullptr, nullptr };
// null terminated array of PhysicsObject pointers
PhysicsObject* physicsObjects[] = { nullptr, nullptr, nullptr, nullptr, nullptr, nullptr };
// The view projection matrix aka the camera
mat4 P;
mat4 View;
mat4 PV;
vec3 cameraPosition;
MeshObject* sphere;
PhysicsObject* po;
PhysicsWorld physics;
// uniform locations - add more as you see fit
TextureUnit tex;
ConstantLocation pvLocation;
ConstantLocation mLocation;
ConstantLocation tintLocation;
Texture* particleImage;
ParticleSystem* particleSystem;
double lastTime;
void update() {
double t = System::time() - startTime;
double deltaT = t - lastTime;
//Kore::log(Info, "%f\n", deltaT);
lastTime = t;
Kore::Audio::update();
Graphics::begin();
Graphics::clear(Graphics::ClearColorFlag | Graphics::ClearDepthFlag, 0xff9999FF, 1000.0f);
Graphics::setFloat4(tintLocation, vec4(1, 1, 1, 1));
program->set();
angle += 0.3f * deltaT;
float x = 0 + 3 * Kore::cos(angle);
float z = 0 + 3 * Kore::sin(angle);
cameraPosition.set(x, 2, z);
//PV = mat4::Perspective(60, (float)width / (float)height, 0.1f, 100) * mat4::lookAt(vec3(0, 2, -3), vec3(0, 2, 0), vec3(0, 1, 0));
P = mat4::Perspective(60, (float)width / (float)height, 0.1f, 100);
View = mat4::lookAt(vec3(x, 2, z), vec3(0, 2, 0), vec3(0, 1, 0));
PV = P * View;
Graphics::setMatrix(pvLocation, PV);
// iterate the MeshObjects
MeshObject** current = &objects[0];
while (*current != nullptr) {
// set the model matrix
Graphics::setMatrix(mLocation, (*current)->M);
(*current)->render(tex);
++current;
}
// Update the physics
physics.Update(deltaT);
PhysicsObject** currentP = &physics.physicsObjects[0];
while (*currentP != nullptr) {
(*currentP)->UpdateMatrix();
Graphics::setMatrix(mLocation, (*currentP)->Mesh->M);
(*currentP)->Mesh->render(tex);
++currentP;
}
particleSystem->update(deltaT);
particleSystem->render(tex, particleImage, mLocation, View);
Graphics::end();
Graphics::swapBuffers();
}
void SpawnSphere(vec3 Position, vec3 Velocity) {
PhysicsObject* po = new PhysicsObject();
po->SetPosition(Position);
po->Velocity = Velocity;
po->Collider.radius = 0.2f;
po->Mass = 5;
po->Mesh = sphere;
// The impulse should carry the object forward
// Use the inverse of the view matrix
po->ApplyImpulse(Velocity);
physics.AddObject(po);
}
void keyDown(KeyCode code, wchar_t character) {
if (code == Key_Space) {
// The impulse should carry the object forward
// Use the inverse of the view matrix
vec4 impulse(0, 0.4, 2, 0);
mat4 viewI = View;
viewI.Invert();
impulse = viewI * impulse;
vec3 impulse3(impulse.x(), impulse.y(), impulse.z());
SpawnSphere(cameraPosition + impulse3 *0.2f, impulse3);
}
}
void keyUp(KeyCode code, wchar_t character) {
if (code == Key_Left) {
// ...
}
}
void mouseMove(int x, int y, int movementX, int movementY) {
}
void mousePress(int button, int x, int y) {
}
void mouseRelease(int button, int x, int y) {
}
void init() {
FileReader vs("shader.vert");
FileReader fs("shader.frag");
vertexShader = new Shader(vs.readAll(), vs.size(), VertexShader);
fragmentShader = new Shader(fs.readAll(), fs.size(), FragmentShader);
// This defines the structure of your Vertex Buffer
VertexStructure structure;
structure.add("pos", Float3VertexData);
structure.add("tex", Float2VertexData);
structure.add("nor", Float3VertexData);
program = new Program;
program->setVertexShader(vertexShader);
program->setFragmentShader(fragmentShader);
program->link(structure);
tex = program->getTextureUnit("tex");
pvLocation = program->getConstantLocation("PV");
mLocation = program->getConstantLocation("M");
tintLocation = program->getConstantLocation("tint");
objects[0] = new MeshObject("Base.obj", "Level/basicTiles6x6.png", structure);
objects[0]->M = mat4::Translation(0.0f, 1.0f, 0.0f);
sphere = new MeshObject("ball_at_origin.obj", "Level/unshaded.png", structure);
SpawnSphere(vec3(0, 2, 0), vec3(0, 0, 0));
Graphics::setRenderState(DepthTest, true);
Graphics::setRenderState(DepthTestCompare, ZCompareLess);
Graphics::setTextureAddressing(tex, U, Repeat);
Graphics::setTextureAddressing(tex, V, Repeat);
particleImage = new Texture("SuperParticle.png", true);
particleSystem = new ParticleSystem(100, structure);
}
}
int kore(int argc, char** argv) {
Application* app = new Application(argc, argv, width, height, 0, false, "Exercise7");
init();
app->setCallback(update);
startTime = System::time();
lastTime = 0.0f;
Kore::Mixer::init();
Kore::Audio::init();
Keyboard::the()->KeyDown = keyDown;
Keyboard::the()->KeyUp = keyUp;
Mouse::the()->Move = mouseMove;
Mouse::the()->Press = mousePress;
Mouse::the()->Release = mouseRelease;
app->start();
delete app;
return 0;
}
老师要我们加代码的地方有个注释。 View 矩阵“View”的变量在“namespace”中。我只将 namespace 用作库，但这个库没有名称。那么如何使用呢？
评论说我们应该使用矩阵 V。所以我只是将 V = Inverse View Matrix * Model Matrix 添加到代码中并删除了旋转？
对于愚蠢的问题，我很抱歉，它应该是针对初学者的类(class)，但实际上什么都不是。对于编程部分，讲义不是很有帮助，我只找到了 OpenGL 或 Unity 或 Direct X 的教程，而没有使用它们中的任何一个。
请帮帮我，我需要在星期六早上之前提交这个，我已经花了最后两天尝试代码，但到目前为止我一无所获!
您可以在这里找到全部内容:https://github.com/TUDGameTechnology/Exercise7
最佳答案
您无需执行任何特殊操作即可访问未命名的命名空间。这thread解释更多。
您很可能正在尝试在无法看到您的命名空间的方法中引用 View，因为它们在您的文件中定义的顺序。
update 方法中的这一行:
particleSystem->render(tex, particleImage, mLocation, View);
已经将 View 传递给 render 方法。
void render(TextureUnit tex, Texture* image, ConstantLocation mLocation, mat4 V)
这意味着在这种情况下，mat4 v 是您的相机 View 。
关于c++ - 广告牌 C++，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34338432/