fix: Always vflip cubemaps (#7)

Fixes #6 (not sure if it breaks other cubemaps)

Author: sshcrack

shadertoy/NodeEditor/PipelineEditor.cpp

@@ -79,7 +79,8 @@ static constexpr auto initialShader = R"(void mainImage( out vec4 fragColor, in
 }
 )";
 
-static constexpr auto initialCubeMap = R"(void mainCubemap( out vec4 fragColor, in vec2 fragCoord, in vec3 rayOri, in vec3 rayDir )
+static constexpr auto initialCubeMap =
+    R"(void mainCubemap( out vec4 fragColor, in vec2 fragCoord, in vec3 rayOri, in vec3 rayDir )
 {
     // Ray direction as color
     vec3 col = 0.5 + 0.5*rayDir;
@@ -894,10 +895,14 @@ std::unique_ptr<Pipeline> PipelineEditor::buildPipeline() {
                     [&] { HelloImGui::Log(HelloImGui::LogLevel::Error, "Failed to compile shader %s", node->name.c_str()); });
                 pipeline->addPass(dynamic_cast<EditorShader*>(node)->editor.getText(), node->type, target, std::move(channels),
                                   node == sinkNode);
-                if(target.front().t1)
-                    textureMap.emplace(node,
-                                       DoubleBufferedTex{ target.front().t1->getTexture(), target.front().t2->getTexture(),
-                                                          node->type == NodeType::CubeMap ? TexType::CubeMap : TexType::Tex2D });
+
+                if(target.front().t1) {
+                    auto texType = node->type == NodeType::CubeMap ? TexType::CubeMap : TexType::Tex2D;
+
+                    textureMap.emplace(
+                        node, DoubleBufferedTex{ target.front().t1->getTexture(), target.front().t2->getTexture(), texType });
+                }
+
                 break;
             }
             case NodeClass::LastFrame: {
@@ -1579,18 +1584,21 @@ void PipelineEditor::loadFromShaderToy(const std::string& path) {
         return &texture;
     };
     std::unordered_set<std::string> passIds;
+    // Look at any index.html at EffectPass.prototype.NewTexture if(assetID_to_cubemapBuferId)
     const auto isDynamicCubeMap = [&](nlohmann::json& tex) {
         const auto id = tex.at("id").get<std::string>();
-        return passIds.count(id) != 0;
+        return id == "4dX3Rr";
     };
     std::string common;
     for(auto& pass : renderPasses) {
         if(pass.at("name").get<std::string>().empty()) {
             pass.at("name") = generateUniqueName(pass.at("type").get<std::string>());
         }
+
         if(pass.at("outputs").empty()) {
             pass.at("outputs").push_back(nlohmann::json::object({ { "id", "tmp" + std::to_string(nextId()) } }));
         }
+
         passIds.insert(pass.at("outputs")[0].at("id").get<std::string>());
     }
     for(auto& pass : renderPasses) {
@@ -1601,7 +1609,9 @@ void PipelineEditor::loadFromShaderToy(const std::string& path) {
             common = code + '\n';
         } else if(type == "image" || type == "buffer" || type == "cubemap") {
             const auto output = pass.at("outputs")[0].at("id").get<std::string>();
-            auto& node = spawnShader(type != "cubemap" ? NodeType::Image : NodeType::CubeMap);
+            auto nodeType = type == "cubemap" ? NodeType::CubeMap : NodeType::Image;
+
+            auto& node = spawnShader(nodeType);
             node.editor.setText(code);
             node.name = name;
             newShaderNodes.emplace(output, &node);
@@ -1662,12 +1672,30 @@ void PipelineEditor::loadFromShaderToy(const std::string& path) {
 
             for(auto& input : pass.at("inputs")) {
                 auto inputType = input.at("type").get<std::string>();
-                if(!(inputType == "buffer" || (inputType == "cubemap" && isDynamicCubeMap(input)))) {
+                bool dynamicCubeMap = inputType == "cubemap" && isDynamicCubeMap(input);
+                if(inputType != "buffer" && !dynamicCubeMap) {
                     continue;
                 }
 
                 auto channel = input.at("channel").get<uint32_t>();
                 auto inputId = input.at("id").get<std::string>();
+
+                // There is only one dynamic cube map in Shadertoy, so we can safely use the first one
+                if(dynamicCubeMap) {
+                    for(auto& innerPass : renderPasses) {
+                        if(innerPass.at("type").get<std::string>() != "cubemap") {
+                            continue;
+                        }
+
+                        if(innerPass.at("outputs").empty())
+                            continue;
+
+                        inputId = innerPass.at("outputs")[0].at("id").get<std::string>();
+                        channel = innerPass.at("outputs")[0].at("channel").get<uint32_t>();
+                        break;
+                    }
+                }
+
                 if(!newShaderNodes.count(inputId)) {
                     // Shadertoy doesn't fail when an input is missing, so we create a default dummy node
                     auto& inputNode = spawnShader(inputType != "cubemap" ? NodeType::Image : NodeType::CubeMap);

shadertoy/OpenGL.cpp

@@ -102,12 +102,12 @@ constexpr Vec3 cubeMapVertexPos[8] = { { -1.0f, -1.0f, -1.0f }, { -1.0f, -1.0f,
                                        { 1.0f, 1.0f, -1.0f },   { 1.0f, 1.0f, 1.0f } };
 // left-bottom left-top right-top right-bottom
 constexpr uint32_t cubeMapVertexIndex[6][4] = {
-    { 4, 6, 7, 5 },  // right
-    { 1, 3, 2, 0 },  // left
-    { 2, 3, 7, 6 },  // top
-    { 1, 0, 4, 5 },  // bottom
-    { 5, 7, 3, 1 },  // back
-    { 0, 2, 6, 4 }   // front
+    { 5, 7, 6, 4 },  // +X (right face)
+    { 0, 2, 3, 1 },  // -X (left face)
+    { 0, 1, 5, 4 },  // +Y (top face)
+    { 3, 2, 6, 7 },  // -Y (bottom face)
+    { 1, 3, 7, 5 },  // +Z (back face)
+    { 4, 6, 2, 0 }   // -Z (front face)
 };
 
 struct VertexCubeMap final {  // NOLINT(cppcoreguidelines-pro-type-member-init)
@@ -395,6 +395,15 @@ class RenderPass final {
                     VertexCubeMap{ ImVec2{ base.x + size.x, base.y + size.y }, ImVec2{ uniformSize.x, 0.0 },
                                    cubeMapVertexPos[cubeMapVertexIndex[idx][3]] },  // right-bottom
                 };
+
+                // For Y-flipped cubemaps, also flip Y coordinates of all faces
+                // to match ShaderToy's UNPACK_FLIP_Y_WEBGL behavior
+                // CubeMaps are always Y-flipped
+                for(auto& [pos, coord, point] : vertices) {
+                    // Flip the 3D point's Y coordinate
+                    point[1] = -point[1];
+                }
+
                 for(auto& [pos, coord, point] : vertices) {
                     pos.x = pos.x / fbSize.x * 2.0f - 1.0f;
                     pos.y = 1.0f - pos.y / fbSize.y * 2.0f;
@@ -578,8 +587,8 @@ class GLVolumeObject final : public TextureObject {
         glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAX_LEVEL, static_cast<GLint>(std::log2(size)));
         GLenum internalFormat = channels == 1 ? GL_R8 : GL_RGBA;
         GLenum format = channels == 1 ? GL_RED : GL_RGBA;
-        glTexImage3D(GL_TEXTURE_3D, 0, internalFormat, static_cast<GLsizei>(size), static_cast<GLsizei>(size), static_cast<GLsizei>(size),
-                     0, format, GL_UNSIGNED_BYTE, data);  // R8G8B8A8
+        glTexImage3D(GL_TEXTURE_3D, 0, internalFormat, static_cast<GLsizei>(size), static_cast<GLsizei>(size),
+                     static_cast<GLsizei>(size), 0, format, GL_UNSIGNED_BYTE, data);  // R8G8B8A8
         glGenerateMipmap(GL_TEXTURE_3D);
         glBindTexture(GL_TEXTURE_3D, GL_NONE);
     }