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feat: add multi-expression plotting with color selection etc #11

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189 changes: 89 additions & 100 deletions src/core/Core/Application.cpp
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Original file line number Diff line number Diff line change
@@ -1,14 +1,11 @@
#include "Application.hpp"

#include <SDL2/SDL.h>
#include <backends/imgui_impl_sdl2.h>
#include <backends/imgui_impl_sdlrenderer2.h>
#include <imgui.h>

#include <memory>
#include <string>
#include <vector>

#include "Core/DPIHandler.hpp"
#include "Core/Debug/Instrumentor.hpp"
#include "Core/Log.hpp"
Expand All @@ -18,6 +15,8 @@
#include "exprtk.hpp"
#include "funcs.hpp"

using namespace std;
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@nsh07 nsh07 Oct 23, 2025

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Please revert the use of using namespace std. It is bad practice and it will create trouble at some point, if not now. See https://stackoverflow.com/questions/1452721/whats-the-problem-with-using-namespace-std for further reading.


namespace App {

Application::Application(const std::string& title) {
Expand Down Expand Up @@ -112,15 +111,43 @@ ExitStatus App::Application::run() {
const ImVec2 base_pos = viewport->Pos;
const ImVec2 base_size = viewport->Size;

static char function[1024] = "tanh(x)";
static float zoom = 100.0f;
struct GraphExpr {
char expr[1024];
ImVec4 col;
bool on;
};
static vector<GraphExpr> exprs = {{"sin(x)", ImVec4(0.0f, 0.5f, 1.0f, 1.0f), true}};

// Left Pane (expression)
{
ImGui::SetNextWindowPos(base_pos);
ImGui::SetNextWindowSize(ImVec2(base_size.x * 0.25f, base_size.y));
ImGui::Begin("Left Pane", nullptr, ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoTitleBar);
ImGui::InputTextMultiline("##search", function, sizeof(function), ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 4));
ImGui::Text("Expressions:");
ImGui::Separator();
for (int i = 0; i < exprs.size(); i++) {
ImGui::PushID(i);
ImGui::InputTextMultiline(("##expr" + to_string(i)).c_str(), exprs[i].expr, sizeof(exprs[i].expr), ImVec2(-FLT_MIN, ImGui::GetTextLineHeight() * 2));
ImGui::SameLine();
ImGui::ColorEdit3(("##color" + to_string(i)).c_str(), (float*)&exprs[i].col, ImGuiColorEditFlags_NoInputs);
ImGui::Checkbox(("##enabled" + to_string(i)).c_str(), &exprs[i].on);
ImGui::SameLine();
ImGui::Text("Enabled");
if (exprs.size() > 1) {
ImGui::SameLine();
if (ImGui::Button("Delete")) {
exprs.erase(exprs.begin() + i);
i--;
}
}
ImGui::Separator();
ImGui::PopID();
}
if (ImGui::Button("Add Expression")) {
exprs.push_back({"x^2", ImVec4(1.0f, 0.5f, 0.0f, 1.0f), true});
}
ImGui::Separator();
ImGui::SliderFloat("Graph Scale", &zoom, 10.0f, 500.0f, "%.1f");
ImGui::End();
}
Expand All @@ -139,106 +166,68 @@ ExitStatus App::Application::run() {
float lineThickness = 6.0f;
draw_list->AddLine(ImVec2(canvas_p0.x, origin.y), ImVec2(canvas_p1.x, origin.y), IM_COL32(0, 0, 0, 255), lineThickness);
draw_list->AddLine(ImVec2(origin.x, canvas_p0.y), ImVec2(origin.x, canvas_p1.y), IM_COL32(0, 0, 0, 255), lineThickness);
std::vector<ImVec2> points;

// (f(t), g(t))
std::string func_str(function);


bool plotted = false;

if (!func_str.empty() && func_str.front() == '(' && func_str.back() == ')') {
const std::string inner = func_str.substr(1, func_str.size() - 2);
// top-level comma separating f and g
int depth = 0;
size_t split_pos = std::string::npos;
for (size_t i = 0; i < inner.size(); ++i) {
char c = inner[i];
if (c == '(')
++depth;
else if (c == ')')
--depth;
else if (c == ',' && depth == 0) {
split_pos = i;
break;
}
}

if (split_pos != std::string::npos) {
std::string fx = trim(inner.substr(0, split_pos));
std::string gx = trim(inner.substr(split_pos + 1));

// Prepare exprtk
double t = 0.0;
exprtk::symbol_table<double> sym_t;
sym_t.add_constants();
addConstants(sym_t);
sym_t.add_variable("t", t);

exprtk::expression<double> expr_fx;
expr_fx.register_symbol_table(sym_t);
exprtk::expression<double> expr_gx;
expr_gx.register_symbol_table(sym_t);

exprtk::parser<double> parser;
bool ok_fx = parser.compile(fx, expr_fx);
bool ok_gx = parser.compile(gx, expr_gx);

if (ok_fx && ok_gx) {
// iterate t
const double t_min = -10.0;
const double t_max = 10.0;
const double t_step = 0.02;

for (t = t_min; t <= t_max; t += t_step) {
const double vx = expr_fx.value();
const double vy = expr_gx.value();


ImVec2 screen_pos(origin.x + static_cast<float>(vx * zoom),
origin.y - static_cast<float>(vy * zoom));
points.push_back(screen_pos);
for (const auto& e : exprs) {
if (!e.on) continue;
vector<ImVec2> pts;
string s(e.expr);
bool ok = false;

if (!s.empty() && s.front() == '(' && s.back() == ')') {
string inner = s.substr(1, s.size() - 2);
int d = 0;
size_t pos = string::npos;
Comment on lines +173 to +179
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@nsh07 nsh07 Oct 23, 2025

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Also refrain from shortening variables for no reason. It makes the code unreadable. s should be renamed to func_str, d should be renamed to depth, and ok should be renamed to plotted.

for (size_t i = 0; i < inner.size(); ++i) {
char c = inner[i];
if (c == '(') ++d;
else if (c == ')') --d;
else if (c == ',' && d == 0) {
pos = i;
break;
}
}
if (pos != string::npos) {
string fx = trim(inner.substr(0, pos));
string gx = trim(inner.substr(pos + 1));
double t = 0.0;
exprtk::symbol_table<double> st;
st.add_constants();
addConstants(st);
st.add_variable("t", t);
exprtk::expression<double> ef, eg;
Comment on lines +193 to +197
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@nsh07 nsh07 Oct 23, 2025

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Same thing here, rename st to symbolTable and ef, eg to expr_fx, expr_gx

ef.register_symbol_table(st);
eg.register_symbol_table(st);
exprtk::parser<double> p;
if (p.compile(fx, ef) && p.compile(gx, eg)) {
for (t = -10.0; t <= 10.0; t += 0.02) {
double vx = ef.value();
double vy = eg.value();
pts.push_back(ImVec2(origin.x + vx * zoom, origin.y - vy * zoom));
}
ImU32 c = IM_COL32(e.col.x * 255, e.col.y * 255, e.col.z * 255, 255);
draw_list->AddPolyline(pts.data(), pts.size(), c, ImDrawFlags_None, lineThickness);
ok = true;
}

// Draw curve
draw_list->AddPolyline(points.data(),
points.size(),
IM_COL32(64, 128, 199, 255),
ImDrawFlags_None,
lineThickness);
plotted = true;
}
}
}

if (!plotted) {
// Fallback to y = f(x) plotting using variable x
double x;

exprtk::symbol_table<double> symbolTable;
symbolTable.add_constants();
addConstants(symbolTable);
symbolTable.add_variable("x", x);

exprtk::expression<double> expression;
expression.register_symbol_table(symbolTable);

exprtk::parser<double> parser;
parser.compile(function, expression);

for (x = -canvas_sz.x / (2 * zoom); x < canvas_sz.x / (2 * zoom); x += 0.05) {
const double y = expression.value();


ImVec2 screen_pos(origin.x + x * zoom, origin.y - y * zoom);
points.push_back(screen_pos);
if (!ok) {
double x;
exprtk::symbol_table<double> st;
st.add_constants();
addConstants(st);
st.add_variable("x", x);
exprtk::expression<double> expr;
expr.register_symbol_table(st);
exprtk::parser<double> p;
Comment on lines +215 to +221
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@nsh07 nsh07 Oct 23, 2025

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Same thing, rename the variables here as well

if (p.compile(s, expr)) {
for (x = -canvas_sz.x / (2 * zoom); x < canvas_sz.x / (2 * zoom); x += 0.05) {
double y = expr.value();
pts.push_back(ImVec2(origin.x + x * zoom, origin.y - y * zoom));
}
ImU32 c = IM_COL32(e.col.x * 255, e.col.y * 255, e.col.z * 255, 255);
draw_list->AddPolyline(pts.data(), pts.size(), c, ImDrawFlags_None, lineThickness);
}
}

draw_list->AddPolyline(points.data(),
points.size(),
IM_COL32(199, 68, 64, 255),
ImDrawFlags_None,
lineThickness);
}

ImGui::End();
Expand Down