path: root/3d/rigidbody/main.cpp

#include "../../shared_cpp/Renderer3d.h"
#include "../../shared_cpp/RenderShared.h"
#include "../../shared_cpp/Camera3d.h"
#include "../../shared_cpp/types.h"
#include "../../shared_cpp/WebglContext.h"
#include "../../shared_cpp/mathlib.h"
#include "../../shared_cpp/MainLoop.h"
#include <cstdio>
#include <cmath>
#include <emscripten/html5.h>
#include <unistd.h>
#include <pthread.h>
#include <cmath>
#include <cfloat>

struct Impulse {
    Vector3 force = { 0, 0, 0 };
    Vector3 pointOfApplication = { 0, 0, 0 };
    float32 timeOfApplicationSeconds = 0.016f;
    float32 timeAppliedSeconds = 0.f;
    bool isDead = false;
};

const int32 MAX_IMPULSES = 4;

struct Rigidbody3d {
    int32 numImpulses = 0;
    Impulse activeImpulses[MAX_IMPULSES];
    Vector3 velocity;
    Vector3 position;
    float32 mass = 1.f;

    Vector3 rotationalVelocity;
    Quaternion rotation;
    float32 momentOfInertia = 1.f;

    void reset() {
        numImpulses = 0;
        velocity = { 0, 0, 0};
        rotationalVelocity = { 0, 0, 0 };
    }

    void applyImpulse(Impulse i) {
        if (numImpulses > MAX_IMPULSES) {
            printf("Unable to apply impulse. Buffer full.\n");
            return;
        }

        activeImpulses[numImpulses] = i;
        numImpulses++;
    }

    void update(float32 deltaTimeSeconds) {
        // Apply gravity
        velocity += (Vector3 { 0.f, -9.8f, 0.f } * deltaTimeSeconds);

        Vector3 force = { 0.f, 0.f, 0.f };
        Vector3 torque = { 0.f, 0.f, 0.f };
        for (int32 idx = 0; idx < numImpulses; idx++) {
            Impulse& i = activeImpulses[idx];

            float32 nextTimeAppliedSeconds = i.timeAppliedSeconds + deltaTimeSeconds;
            if (nextTimeAppliedSeconds >= i.timeOfApplicationSeconds) {
                nextTimeAppliedSeconds = i.timeOfApplicationSeconds;
                i.isDead = true;
            }
            
            float32 impulseDtSeconds = nextTimeAppliedSeconds - i.timeAppliedSeconds;
            Vector3 forceToApply = i.force * (impulseDtSeconds / i.timeOfApplicationSeconds);
            force += forceToApply;

            torque += i.pointOfApplication.cross(force).dot(forceToApply);
            i.timeAppliedSeconds = nextTimeAppliedSeconds;
        }
        
        Vector3 acceleration = force / mass;
        velocity += (acceleration * deltaTimeSeconds);
        position += (velocity * deltaTimeSeconds);

	    Vector3 rotationalAcceleration = torque / momentOfInertia;
		rotationalVelocity += (rotationalAcceleration * deltaTimeSeconds);

        Vector3 drDt = rotationalVelocity * deltaTimeSeconds;

        Quaternion rotationVelocityQuat = quaternionFromRotation(Vector3(1, 0, 0), drDt.x)
            * quaternionFromRotation(Vector3(0, 1, 0), drDt.y)
            * quaternionFromRotation(Vector3(0, 0, 1), drDt.z);
		rotation = rotation * rotationVelocityQuat;

        for (int32 idx = 0; idx < numImpulses; idx++) {
            if (activeImpulses[idx].isDead) {
                for (int j = idx + 1; j < numImpulses; j++) {
                    activeImpulses[j - 1] = activeImpulses[j];
                }

                idx = idx - 1;
                numImpulses--;
            }
        }
    }
};

float32 bounds = 20.f;

struct Sphere {
	Mesh3d mesh;
    Rigidbody3d body;

	void load(Renderer3d* renderer) {
        const float32 scale = 3.f;
        const float32 angleIncrements = 2.f;
        const int32 numFaces = static_cast<int32>((180.f / angleIncrements + 1) * (360.f / angleIncrements + 1));
        const int32 numVertices = 4.f * numFaces;
        const int32 numIndices = 6 * numFaces;
        Vertex3d* vertices = new Vertex3d[numVertices];
        GLuint* indices = new GLuint[numIndices];

        // Generate vertices and indices
        GLint index = 0;
        int32 vidx = 0;
        int32 iidx = 0;
        for (float phi = 0.0; phi <= 180; phi += angleIncrements) {
            const auto cosPhi = cos(DEG_TO_RAD(phi));
            const auto sinPhi = sin(DEG_TO_RAD(phi));

            const auto nextCosPhi = cos(DEG_TO_RAD(phi + angleIncrements));
            const auto nextSinPhi = sin(DEG_TO_RAD(phi + angleIncrements));

            for (float theta = 0.0; theta <= 360; theta += angleIncrements) {
                auto color = colorFromHex(randomFloatBetween(0.f, 255.f), randomFloatBetween(0.f, 255.f), randomFloatBetween(0.f, 255.f), 255.f);
                const auto cosTheta = cos(DEG_TO_RAD(theta));
                const auto sinTheta = sin(DEG_TO_RAD(theta));

                const auto nextSinTheta = sin(DEG_TO_RAD(theta + angleIncrements));
                const auto nextCosTheta =  cos(DEG_TO_RAD(theta + angleIncrements));

                // Top Left Point
                auto topLeftPoint = Vector3(scale * sinPhi * cosTheta, scale * sinPhi * sinTheta, scale * cosPhi);
                auto topLeftIdx = index++;
                vertices[vidx++] = { topLeftPoint, topLeftPoint.normalize(), color };

                // Bottom Left Point
                auto bottomLeftPoint = Vector3(scale * nextSinPhi * cosTheta, scale * nextSinPhi * sinTheta, scale * nextCosPhi);
                auto bottomLeftIdx = index++;
                vertices[vidx++] = { bottomLeftPoint, bottomLeftPoint.normalize(), color };

                // Bottom Right Point
                auto bottomRightPoint = Vector3(scale * nextSinPhi * nextCosTheta, scale * nextSinPhi * nextSinTheta, scale * nextCosPhi);
                auto bottomRightIdx = index++;
                vertices[vidx++] = { bottomRightPoint, bottomRightPoint.normalize(), color };

                // Top Right Point
                auto topRightPoint = Vector3(scale * sinPhi * nextCosTheta, scale * sinPhi * nextSinTheta, scale * cosPhi);
                auto topRightIdx = index++;
                vertices[vidx++] = { topRightPoint, topRightPoint.normalize(), color };

                indices[iidx++] = (topLeftIdx);
                indices[iidx++] = (bottomLeftIdx);
                indices[iidx++] = (bottomRightIdx);
                indices[iidx++] = (bottomRightIdx);
                indices[iidx++] = (topLeftIdx);
                indices[iidx++] = (topRightIdx);
            }
        }

		mesh.load(vertices, numVertices, indices, numIndices, renderer);

        body.position = Vector3 { 0.f, 0.f, 0.f };
        body.velocity = Vector3 { 0.f, 0.f, 0.f };

        float32 singleFaceArea = scale;
        body.momentOfInertia = (body.mass * singleFaceArea) / 6.f;

        delete [] vertices;
        delete [] indices;
	}

	void update(float32 dtSeconds) {
        body.update(dtSeconds);

        if (body.position.x > bounds) {
            body.position.x = bounds;
            body.velocity.x = -body.velocity.x;
        }
        else if (body.position.x < -bounds) {
            body.position.x = -bounds;
            body.velocity.x = -body.velocity.x;
        }

        if (body.position.y > bounds) {
            body.position.y = bounds;
            body.velocity.y = -body.velocity.y;
        }
        else if (body.position.y < -bounds) {
            body.position.y = -bounds;
            body.velocity.y = -body.velocity.y;
        }

        if (body.position.z > bounds) {
            body.position.z = bounds;
            body.velocity.z = -body.velocity.z;
        }
        else if (body.position.z < -bounds) {
            body.position.z = -bounds;
            body.velocity.z = -body.velocity.z;
        }

        mesh.model = body.rotation.toMatrix().translate(body.position);

	}

	void render(Renderer3d* renderer) {
		mesh.render(renderer);
	}

	void unload() {
		mesh.unload();
	}
};

EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
EM_BOOL onStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);
EM_BOOL onForceApplicationRequested(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData);

void load();
void update(float32 time, void* userData);
void unload();

WebglContext context;
Renderer3d renderer;
Camera3d camera;
MainLoop mainLoop;
bool isIntersectingPointer = false;

const int32 numSpheres = 2;
Sphere sphereList[numSpheres];

int main() {
	context.init("#gl_canvas");
    emscripten_set_click_callback("#gl_canvas_play", NULL, false, onPlayClicked);
    emscripten_set_click_callback("#gl_canvas_stop", NULL, false, onStopClicked);
    emscripten_set_click_callback("#force_apply", NULL, false, onForceApplicationRequested);
    return 0;
}

void load() {
    renderer.load(&context);

    sphereList[0].load(&renderer);
    sphereList[0].body.mass = 10.f;
    sphereList[0].body.position = Vector3(10.f, 0, -5);
    sphereList[0].body.velocity = Vector3(-10.f, 10.f, 10.f);
    sphereList[0].body.rotationalVelocity = Vector3(1.f, 1.f, 1.f);

    sphereList[1].load(&renderer);
    sphereList[1].body.mass = 6.f;
    sphereList[1].body.position = Vector3(-10.f, 0, 5);
    sphereList[1].body.velocity = Vector3(10.f, 10.f, -10.f);
    sphereList[1].body.rotationalVelocity = Vector3(1.f, 1.f, 1.f);

	camera.projection  = Mat4x4().getPerspectiveProjection(0.1f, 10000.f, DEG_TO_RAD(45.f), 800.f / 600.f);
	camera.view = Mat4x4().translate({ 0, 0, -40.f });
    mainLoop.run(update);
}

void update(float32 deltaTimeSeconds, void* userData) {
    for (int32 idx = 0; idx < numSpheres; idx++) {
        sphereList[idx].update(deltaTimeSeconds);
    }

	// Renderer
	renderer.render(&camera);
    for (int32 idx = 0; idx < numSpheres; idx++) {
        sphereList[idx].render(&renderer);
    }
}

void unload() {
    mainLoop.stop();
    renderer.unload();
    for (int32 idx = 0; idx < numSpheres; idx++) {
        sphereList[idx].unload();
    }
}

//
// Interactions with DOM handled below
//
EM_BOOL onPlayClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
    printf("Play clicked\n");
    
    load();
    return true;
}

EM_BOOL onStopClicked(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
    printf("Stop clicked\n");
    unload();
    return true;
}

EM_BOOL onForceApplicationRequested(int eventType, const EmscriptenMouseEvent* mouseEvent, void* userData) {
    printf("Force applied\n");
    Impulse base;
    base.force = { 0, 10000, 0 };
    base.pointOfApplication = { -15, -15, 0 };
    for (int32 idx = 0; idx < numSpheres; idx++) {
        sphereList[idx].body.applyImpulse(base);
    }
    return true;
}