osltoy - Feature Request: autodetect output color variable

src/osltoy/osltoyapp.cpp

@@ -23,6 +23,7 @@
 #include <QPixmap>
 #include <QPlainTextEdit>
 #include <QPushButton>
+#include <QRadioButton>
 #include <QScrollArea>
 #include <QSlider>
 #include <QSpinBox>
@@ -721,6 +722,11 @@ OSLToyMainWindow::OSLToyMainWindow(OSLToyRenderer* rend, int xr, int yr)
     connect(maintimer, &QTimer::timeout, this,
             &OSLToyMainWindow::timed_rerender_trigger);
     maintimer->start();
+
+    // Provide the callback to the renderer
+    m_renderer->set_output_getter([this]() {
+        return this->selected_output();  // Return the selected output
+    });
 }
 
 
@@ -1249,6 +1255,25 @@ OSLToyMainWindow::build_shader_group()
     }
     renderer()->set_shadergroup(group);
 
+    // Doing OSLQuery here before the getattribute calls to
+    // set first output param in param list as renderer output if none selected
+    if (m_selectedoutput.empty()) {
+        OSLQuery oslquery = ss->oslquery(
+            *group, 0);  // can I assume that there is only ever one group?
+        for (size_t p = 0; p < oslquery.nparams(); ++p) {
+            auto param = oslquery.getparam(p);
+            // Has to be output and vec3, so we can display as color
+            if (param->isoutput && param->type.is_vec3()) {
+                m_selectedoutput = param->name;
+                break;
+            }
+        }
+    }
+
+    ustring outputs[] = { m_selectedoutput };
+    ss->attribute(group.get(), "renderer_outputs",
+                  TypeDesc(TypeDesc::STRING, 1), &outputs);
+
     m_shader_uses_time            = false;
     int num_globals_needed        = 0;
     const ustring* globals_needed = nullptr;
@@ -1305,7 +1330,6 @@ OSLToyMainWindow::make_param_adjustment_row(ParamRec* param,
     connect(diddleCheckbox, &QCheckBox::stateChanged, this,
             [&](int state) { set_param_diddle(param, state); });
 #endif
-    layout->addWidget(diddleCheckbox, row, 0);
 
     std::string typetext(param->type.c_str());
     if (param->isclosure)
@@ -1314,8 +1338,38 @@ OSLToyMainWindow::make_param_adjustment_row(ParamRec* param,
         typetext = OSL::fmtformat("struct {}", param->structname);
     if (param->isoutput)
         typetext = OSL::fmtformat("output {}", typetext);
+
+    if ((param->isoutput) && (param->type.is_vec3())) {
+        // Create a radio button for the output parameter
+        auto outputRadioButton = new QRadioButton(this);
+        layout->addWidget(outputRadioButton, row, 0);
+
+        // Label for the output parameter
+        auto nameLabel = new QLabel(
+            OSL::fmtformat("<i>{}</i>&nbsp;  <b>{}</b>", typetext, param->name)
+                .c_str());
+        nameLabel->setTextFormat(Qt::RichText);
+        layout->addWidget(nameLabel, row, 1);
+
+        // Connect the radio button to save the selected output and rerender
+        connect(outputRadioButton, &QRadioButton::toggled, this,
+                [this, param](bool checked) {
+                    if (checked) {
+                        // Save the selected output parameter
+                        m_selectedoutput = param->name;
+                    }
+                });
+
+        // Check the radio button if this parameter is the currently selected output
+        if (m_selectedoutput == param->name)
+            outputRadioButton->setChecked(true);
+
+        return;  // Skip the rest of the function for output parameters
+    }
     //    auto typeLabel = QtUtils::mtmt{}<i>{}</i>", typetext);
     //    layout->addWidget (typeLabel, row, 1);
+    layout->addWidget(diddleCheckbox, row, 0);
+
     auto nameLabel = new QLabel(
         OSL::fmtformat("<i>{}</i>&nbsp;  <b>{}</b>", typetext, param->name)
             .c_str());

src/osltoy/osltoyapp.h

@@ -88,6 +88,8 @@ class OSLToyMainWindow final : public QMainWindow {
 
     OSLToyRenderer* renderer() const { return m_renderer.get(); }
 
+    ustring selected_output() const { return m_selectedoutput; }
+
     ShadingSystem* shadingsys() const;
 
     bool open_file(const std::string& filename);
@@ -153,6 +155,8 @@ private slots:
     // Set up the status bar
     void createStatusBar();
 
+
+
     // Actions. To make these do things, put them in the .cpp and give them
     // bodies. Delete the ones that don't correspond to concepts in your
     // app.
@@ -206,6 +210,9 @@ private slots:
     std::string m_groupname;
     bool m_shader_uses_time = false;
 
+    // The currently selected output
+    ustring m_selectedoutput = ustring("");  // Empty until set by user
+
     std::vector<std::string> m_include_search_paths;
 
 

src/osltoy/osltoyrenderer.cpp

@@ -9,7 +9,9 @@
 
 #include <OSL/hashes.h>
 #include <OSL/oslexec.h>
+#include <OSL/oslquery.h>
 
+#include "osltoyapp.h"
 #include "osltoyrenderer.h"
 
 // Create ustrings for all strings used by the free function renderer services.
@@ -115,6 +117,17 @@ OSLToyRenderer::OSLToyRenderer()
     // That also implies that our normal points to (0,0,1)
     sg.N  = Vec3(0, 0, 1);
     sg.Ng = Vec3(0, 0, 1);
+    // In our SimpleRenderer, the "renderstate" itself just a pointer to
+    // the ShaderGlobals.
+    // sg.renderstate = &sg;
+}
+
+
+
+void
+OSLToyRenderer::set_output_getter(std::function<ustring()> getter)
+{
+    m_get_selected_output = getter;
 }
 
 
@@ -126,7 +139,19 @@ OSLToyRenderer::render_image()
         m_framebuffer.reset(
             OIIO::ImageSpec(m_xres, m_yres, 3, TypeDesc::FLOAT));
 
-    static ustring outputs[] = { ustring("Cout") };
+    // Use the getter to get the selected output in the app
+    ustring selected_output = ustring("Cout");  // Default to "Cout"
+    if (m_get_selected_output) {
+        selected_output = m_get_selected_output();
+    } else {
+        std::cerr
+            << "Warning: m_get_selected_output() is not set. Using default 'Cout'.\n";
+    }
+
+    ustring outputs[] = { selected_output };
+    m_shadingsys->attribute("renderer_outputs", TypeDesc(TypeDesc::STRING, 1),
+                            &outputs);
+
     OIIO::paropt popt(0, OIIO::paropt::SplitDir::Tile, 4096);
     shade_image(*shadingsys(), *shadergroup(), &m_shaderglobals_template,
                 m_framebuffer, outputs, ShadePixelCenters, OIIO::ROI(), popt);

src/osltoy/osltoyrenderer.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <functional>
 #include <map>
 #include <memory>
 #include <unordered_map>
@@ -62,6 +63,8 @@ class OSLToyRenderer final : public RendererServices {
 
     OIIO::ImageBuf& framebuffer() { return m_framebuffer; }
 
+    void set_output_getter(std::function<ustring()> getter);
+
     void render_image();
 
     // vvv Methods necessary to be a RendererServices
@@ -89,6 +92,9 @@ class OSLToyRenderer final : public RendererServices {
                               ShaderGlobals* sg, void* val);
 
 private:
+    std::function<ustring()>
+        m_get_selected_output;  // Store the getter function that gets selection from app
+
     OIIO::spin_mutex m_mutex;
     ShadingSystem* m_shadingsys;
     ShaderGroupRef m_group;