Fix T57138: Cycles CMJ failing with viewport samples set to 0.

Can't use INT_MAX, CMJ runs into precision/overflow issues before that.

intern/cycles/blender/addon/properties.py

@@ -194,13 +194,13 @@ class CyclesRenderSettings(bpy.types.PropertyGroup):
         cls.samples = IntProperty(
             name="Samples",
             description="Number of samples to render for each pixel",
-            min=1, max=2147483647,
+            min=1, max=(1 << 24),
             default=128,
         )
         cls.preview_samples = IntProperty(
             name="Preview Samples",
             description="Number of samples to render in the viewport, unlimited if 0",
-            min=0, max=2147483647,
+            min=0, max=(1 << 24),
             default=32,
         )
         cls.preview_pause = BoolProperty(

intern/cycles/blender/blender_sync.cpp

@@ -794,6 +794,9 @@ SessionParams BlenderSync::get_session_params(BL::RenderEngine& b_engine,
 		}
 	}
 
+	/* Clamp samples. */
+	params.samples = min(params.samples, Integrator::MAX_SAMPLES);
+
 	/* tiles */
 	const bool is_cpu = (params.device.type == DEVICE_CPU);
 	if(!is_cpu && !background) {

intern/cycles/render/integrator.h

@@ -55,6 +55,10 @@ public:
 	float sample_clamp_indirect;
 	bool motion_blur;
 
+	/* Maximum number of samples, beyond which we are likely to run into
+	 * precision issues for sampling patterns. */
+	static const int MAX_SAMPLES = (1 << 24);
+
 	int aa_samples;
 	int diffuse_samples;
 	int glossy_samples;

intern/cycles/render/session.h

@@ -84,7 +84,7 @@ public:
 
 		progressive = false;
 		experimental = false;
-		samples = INT_MAX;
+		samples = 1024;
 		tile_size = make_int2(64, 64);
 		start_resolution = INT_MAX;
 		pixel_size = 1;