Extract preview mix-pass material planning

src/legacy_node_stroke_preview_execution_services.h

@@ -1,7 +1,10 @@
 #pragma once
 
+#include "../libs/glm/glm/glm.hpp"
+#include "../libs/glm/glm/ext/matrix_clip_space.hpp"
+
+#include "legacy_canvas_stroke_services.h"
 #include "paint_renderer/compositor.h"
-#include "renderer_api/renderer_api.h"
 
 #include <algorithm>
 #include <cstdint>
@@ -43,4 +46,88 @@ namespace pp::panopainter {
         });
 }
 
+struct LegacyNodeStrokePreviewMixPassPlan {
+    pp::paint_renderer::CanvasStrokeMaterialPlan material {};
+    struct ShaderPlan {
+        glm::vec2 resolution {};
+        glm::vec2 pattern_scale {};
+        float pattern_invert = 0.0f;
+        float pattern_brightness = 0.0f;
+        float pattern_contrast = 0.0f;
+        float pattern_depth = 0.0f;
+        int pattern_blend_mode = 0;
+        glm::vec2 pattern_offset {};
+        int blend_mode = 0;
+        bool use_dual = false;
+        int dual_blend_mode = 0;
+        float dual_alpha = 0.0f;
+        bool use_pattern = false;
+    } shader {};
+};
+
+struct LegacyNodeStrokePreviewMixPassRequest {
+    glm::vec2 resolution {};
+    float pattern_scale = 0.0f;
+    bool pattern_flipx = false;
+    bool pattern_flipy = false;
+    bool pattern_invert = false;
+    float pattern_brightness = 0.0f;
+    float pattern_contrast = 0.0f;
+    float pattern_depth = 0.0f;
+    bool pattern_rand_offset = false;
+    bool pattern_enabled = false;
+    bool pattern_eachsample = false;
+    float tip_wet = 0.0f;
+    float tip_mix = 0.0f;
+    float tip_noise = 0.0f;
+    bool dual_enabled = false;
+    int dual_blend_mode = 0;
+    int pattern_blend_mode = 0;
+    float dual_opacity = 0.0f;
+    int blend_mode = 0;
+};
+
+[[nodiscard]] inline LegacyNodeStrokePreviewMixPassPlan plan_legacy_node_stroke_preview_mix_pass(
+    const LegacyNodeStrokePreviewMixPassRequest& request) noexcept
+{
+    glm::vec2 pattern_scale(request.pattern_scale);
+    if (request.pattern_flipx) {
+        pattern_scale.x *= -1.0f;
+    }
+    if (request.pattern_flipy) {
+        pattern_scale.y *= -1.0f;
+    }
+
+    LegacyNodeStrokePreviewMixPassPlan plan;
+    plan.material = plan_legacy_canvas_stroke_material(
+        pp::paint_renderer::CanvasStrokeMaterialRequest {
+            .destination_feedback_needed = false,
+            .pattern_enabled = request.pattern_enabled,
+            .pattern_eachsample = request.pattern_eachsample,
+            .wet_blend = request.tip_wet > 0.0f,
+            .mix_blend = request.tip_mix > 0.0f,
+            .noise_enabled = request.tip_noise > 0.0f,
+            .dual_brush_enabled = request.dual_enabled,
+            .dual_blend_mode = request.dual_blend_mode,
+            .pattern_blend_mode = request.pattern_blend_mode,
+            .dual_alpha = request.dual_opacity,
+        });
+    plan.shader = LegacyNodeStrokePreviewMixPassPlan::ShaderPlan {
+        .resolution = request.resolution,
+        .pattern_scale = pattern_scale,
+        .pattern_invert = static_cast<float>(request.pattern_invert),
+        .pattern_brightness = request.pattern_brightness,
+        .pattern_contrast = request.pattern_contrast,
+        .pattern_depth = request.pattern_depth,
+        .pattern_blend_mode = plan.material.composite_pass.pattern_blend_mode,
+        .pattern_offset = glm::vec2(request.pattern_rand_offset ? 0.5f : 0.0f),
+        .blend_mode = request.blend_mode,
+        .use_dual = plan.material.composite_pass.use_dual,
+        .dual_blend_mode = plan.material.composite_pass.dual_blend_mode,
+        .dual_alpha = plan.material.composite_pass.dual_alpha,
+        .use_pattern = plan.material.composite_pass.use_pattern,
+    };
+    return plan;
+}
+
 } // namespace pp::panopainter